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Sun ZT, Hu JX, Xie YM, Law KT. Anomalous h/2e Periodicity and Majorana Zero Modes in Chiral Josephson Junctions. PHYSICAL REVIEW LETTERS 2024; 133:056601. [PMID: 39159079 DOI: 10.1103/physrevlett.133.056601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 04/24/2024] [Accepted: 06/26/2024] [Indexed: 08/21/2024]
Abstract
Recent experiments reported that quantum Hall chiral edge state-mediated Josephson junctions (chiral Josephson junctions) could exhibit Fraunhofer oscillations with a periodicity of either h/e [Vignaud et al., Nature (London) 624, 545 (2023)NATUAS0028-083610.1038/s41586-023-06764-4] or h/2e [Amet et al., Science 352, 966 (2016)SCIEAS0036-807510.1126/science.aad6203]. While the h/e-periodic component of the supercurrent had been anticipated theoretically before, the emergence of the h/2e periodicity is still not fully understood. In this Letter, we systematically study the Fraunhofer oscillations of chiral Josephson junctions. In chiral Josephson junctions, the chiral edge states coupled to the superconductors become chiral Andreev edge states. We find that in short junctions, the coupling of the chiral Andreev edge states can trigger the h/2e-magnetic flux periodicity. Our theory resolves the important puzzle concerning the appearance of the h/2e periodicity in chiral Josephson junctions. Furthermore, we explain that when the chiral Andreev edge states couple, a pair of localized Majorana zero modes appear at the ends of the Josephson junction, which are robust and independent of the phase difference between the two superconductors. As the h/2e periodicity and the Majorana zero modes have the same physical origin in the wide junction limit, the Fraunhofer oscillation period could be useful in identifying the regime with Majorana zero modes.
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2
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Lei Z, Cheah E, Schott R, Lehner CA, Zeitler U, Wegscheider W, Ihn T, Ensslin K. Quantum transport in InSb quantum well devices: progress and perspective. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:383001. [PMID: 38815611 DOI: 10.1088/1361-648x/ad5246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 05/30/2024] [Indexed: 06/01/2024]
Abstract
InSb, a narrow-band III-V semiconductor, is known for its small bandgap, small electron effective mass, high electron mobility, large effectiveg-factor, and strong spin-orbit interactions. These unique properties make InSb interesting for both industrial applications and quantum information processing. In this paper, we provide a review of recent progress in quantum transport research on InSb quantum well devices. With advancements in the growth of high-quality heterostructures and micro/nano fabrication, quantum transport experiments have been conducted on low-dimensional systems based on InSb quantum wells. Furthermore, ambipolar operations have been achieved in undoped InSb quantum wells, allowing for a systematic study of the band structure and quantum properties of p-type narrow-band semiconductors. Additionally, we introduce the latest research on InAsSb quantum wells as a continuation of exploring physics in semiconductors with even narrower bandgaps.
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Affiliation(s)
- Zijin Lei
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Erik Cheah
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Rüdiger Schott
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Christian A Lehner
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Uli Zeitler
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Werner Wegscheider
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Thomas Ihn
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Klaus Ensslin
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093 Zurich, Switzerland
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3
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Niu C, Wang M, Zhang Z, Qiu G, Wang Y, Zheng D, Liao PY, Wu W, Ye PD. Superconducting Field-Effect Transistors with Pd xTe-Te Intimate Contacts. ACS NANO 2024; 18:15107-15113. [PMID: 38819119 DOI: 10.1021/acsnano.4c02352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
Superconducting-based electronic devices have shown great potential for future quantum computing applications. One key building block device is a superconducting field-effect transistor based on a superconductor-semiconductor-superconductor Josephson-junction (JJ) with a gate-tunable semiconducting channel. However, the performance of such devices is highly dependent on the quality of the superconductor to semiconductor interface. In this study, we present an alternative method to obtain a high-quality interface by using intimate contact. We investigate the proximity-induced superconductivity in chiral crystal tellurium (Te) and fabricate a PdxTe-Te-PdxTe JJ with an ambipolar supercurrent that is gate-tunable and exhibits multiple Andreev reflections. The semiconducting two-dimensional Te single crystal is grown hydrothermally and partially converted to superconducting PdxTe by controlled annealing. Our work demonstrates a promising path for realizing controllable superconducting electronic devices with high-quality superconducting interfaces; thus, we can continue to advance the field of quantum computing and other interface-based technologies.
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Affiliation(s)
- Chang Niu
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Mingyi Wang
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Zhuocheng Zhang
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Gang Qiu
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Yixiu Wang
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Dongqi Zheng
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Pai-Ying Liao
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Wenzhuo Wu
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Peide D Ye
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
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4
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Gao H, Kong ZZ, Zhang P, Luo Y, Su H, Liu XF, Wang GL, Wang JY, Xu HQ. Gate-defined quantum point contacts in a germanium quantum well. NANOSCALE 2024; 16:10333-10339. [PMID: 38738596 DOI: 10.1039/d4nr00712c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
We report an experimental study of quantum point contacts defined in a high-quality strained germanium quantum well with layered electric gates. At a zero magnetic field, we observed quantized conductance plateaus in units of 2e2/h. Bias-spectroscopy measurements reveal that the energy spacing between successive one-dimensional subbands ranges from 1.5 to 5 meV as a consequence of the small effective mass of the holes and the narrow gate constrictions. At finite magnetic fields perpendicular to the device plane, the edges of the conductance plateaus get split due to the Zeeman effect and Landé g factors were estimated to be ∼6.6 for the holes in the germanium quantum well. We demonstrate that all quantum point contacts in the same device have comparable performances, indicating a reliable and reproducible device fabrication process. Thus, our work lays a foundation for investigating multiple forefronts of physics in germanium-based quantum devices that require quantum point contacts as building blocks.
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Affiliation(s)
- Han Gao
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China.
| | - Zhen-Zhen Kong
- Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China.
| | - Po Zhang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China.
| | - Yi Luo
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China.
- Institute of Condensed Matter and Material Physics, School of Physics, Peking University, Beijing 100871, China
| | - Haitian Su
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China.
- Institute of Condensed Matter and Material Physics, School of Physics, Peking University, Beijing 100871, China
| | - Xiao-Fei Liu
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China.
| | - Gui-Lei Wang
- Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China.
- Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China
- Beijing Superstring Academy of Memory Technology, Beijing 100176, China
| | - Ji-Yin Wang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China.
| | - H Q Xu
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China.
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China.
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5
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Reinhardt S, Ascherl T, Costa A, Berger J, Gronin S, Gardner GC, Lindemann T, Manfra MJ, Fabian J, Kochan D, Strunk C, Paradiso N. Link between supercurrent diode and anomalous Josephson effect revealed by gate-controlled interferometry. Nat Commun 2024; 15:4413. [PMID: 38782910 PMCID: PMC11116472 DOI: 10.1038/s41467-024-48741-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 05/07/2024] [Indexed: 05/25/2024] Open
Abstract
In Josephson diodes the asymmetry between positive and negative current branch of the current-phase relation leads to a polarity-dependent critical current and Josephson inductance. The supercurrent nonreciprocity can be described as a consequence of the anomalous Josephson effect -a φ0-shift of the current-phase relation- in multichannel ballistic junctions with strong spin-orbit interaction. In this work, we simultaneously investigate φ0-shift and supercurrent diode efficiency on the same Josephson junction by means of a superconducting quantum interferometer. By electrostatic gating, we reveal a direct link between φ0-shift and diode effect. Our findings show that spin-orbit interaction in combination with a Zeeman field plays an important role in determining the magnetochiral anisotropy and the supercurrent diode effect.
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Affiliation(s)
- S Reinhardt
- Institut für Experimentelle und Angewandte Physik, University of Regensburg, Regensburg, Germany
| | - T Ascherl
- Institut für Experimentelle und Angewandte Physik, University of Regensburg, Regensburg, Germany
| | - A Costa
- Institut für Theoretische Physik, University of Regensburg, Regensburg, Germany
| | - J Berger
- Institut für Experimentelle und Angewandte Physik, University of Regensburg, Regensburg, Germany
| | - S Gronin
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | - G C Gardner
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
| | - T Lindemann
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA
| | - M J Manfra
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, USA
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA
- School of Materials Engineering, Purdue University, West Lafayette, IN, USA
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA
| | - J Fabian
- Institut für Theoretische Physik, University of Regensburg, Regensburg, Germany
| | - D Kochan
- Institut für Theoretische Physik, University of Regensburg, Regensburg, Germany
- Institute of Physics, Slovak Academy of Sciences, Bratislava, Slovakia
- Center for Quantum Frontiers of Research and Technology (QFort), National Cheng Kung University, Tainan, Taiwan
| | - C Strunk
- Institut für Experimentelle und Angewandte Physik, University of Regensburg, Regensburg, Germany
| | - N Paradiso
- Institut für Experimentelle und Angewandte Physik, University of Regensburg, Regensburg, Germany.
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Levajac V, Barakov H, Mazur GP, van Loo N, Kouwenhoven LP, Nazarov YV, Wang JY. Supercurrent in the Presence of Direct Transmission and a Resonant Localized State. PHYSICAL REVIEW LETTERS 2024; 132:176304. [PMID: 38728734 DOI: 10.1103/physrevlett.132.176304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 01/25/2024] [Accepted: 04/02/2024] [Indexed: 05/12/2024]
Abstract
We study the current-phase relation (CPR) of an InSb-Al nanowire Josephson junction in parallel magnetic fields up to 700 mT. At high magnetic fields and in narrow voltage intervals of a gate under the junction, the CPR exhibits π shifts. The supercurrent declines within these gate intervals and shows asymmetric gate voltage dependence above and below them. We detect these features sometimes also at zero magnetic field. The observed CPR properties are reproduced by a theoretical model of supercurrent transport via interference between direct transmission and a resonant localized state.
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Affiliation(s)
- Vukan Levajac
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Hristo Barakov
- Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands
| | - Grzegorz P Mazur
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Nick van Loo
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Leo P Kouwenhoven
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Yuli V Nazarov
- Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands
| | - Ji-Yin Wang
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
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7
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Li R, Song W, Miao W, Yu Z, Wang Z, Yang S, Gao Y, Wang Y, Chen F, Geng Z, Yang L, Xu J, Feng X, Wang T, Zang Y, Li L, Shang R, Xue Q, He K, Zhang H. Selective-Area-Grown PbTe-Pb Planar Josephson Junctions for Quantum Devices. NANO LETTERS 2024; 24:4658-4664. [PMID: 38563608 DOI: 10.1021/acs.nanolett.4c00900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Planar Josephson junctions are predicted to host Majorana zero modes. The material platforms in previous studies are two-dimensional electron gases (InAs, InSb, InAsSb, and HgTe) coupled to a superconductor such as Al or Nb. Here, we introduce a new material platform for planar JJs, the PbTe-Pb hybrid. The semiconductor, PbTe, was grown as a thin film via selective area epitaxy. The Josephson junction was defined by a shadow wall during the deposition of superconductor Pb. Scanning transmission electron microscopy reveals a sharp semiconductor-superconductor interface. Gate-tunable supercurrents and multiple Andreev reflections are observed. A perpendicular magnetic field causes interference patterns of the switching current, exhibiting Fraunhofer-like and SQUID-like behaviors. We further demonstrate a prototype device for Majorana detection wherein phase bias and tunneling spectroscopy are applicable.
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Affiliation(s)
- Ruidong Li
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Wenyu Song
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Wentao Miao
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zehao Yu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zhaoyu Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Shuai Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yichun Gao
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yuhao Wang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Fangting Chen
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zuhan Geng
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Lining Yang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Jiaye Xu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Xiao Feng
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Hefei National Laboratory, Hefei 230088, China
| | - Tiantian Wang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Hefei National Laboratory, Hefei 230088, China
| | - Yunyi Zang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Hefei National Laboratory, Hefei 230088, China
| | - Lin Li
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Runan Shang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Hefei National Laboratory, Hefei 230088, China
| | - Qikun Xue
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Hefei National Laboratory, Hefei 230088, China
- Southern University of Science and Technology, Shenzhen 518055, China
| | - Ke He
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
- Hefei National Laboratory, Hefei 230088, China
| | - Hao Zhang
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Frontier Science Center for Quantum Information, Beijing 100084, China
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8
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Pan XH, Chen L, Liu DE, Zhang FC, Liu X. Majorana Zero Modes Induced by the Meissner Effect at Small Magnetic Field. PHYSICAL REVIEW LETTERS 2024; 132:036602. [PMID: 38307040 DOI: 10.1103/physrevlett.132.036602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 11/28/2023] [Indexed: 02/04/2024]
Abstract
One key difficulty in realizing Majorana zero modes (MZMs) is the required high magnetic field, which causes serious issues, e.g., shrinks the superconducting gap, reduces topological region, and weakens their robustness against disorders. In this Letter, we propose that the Meissner effect can bring the topological superconducting phase to a superconductor/topological-insulator/superconductor (SC/TI/SC) hybrid system. Remarkably, the required magnetic field strength (<10 mT) to support MZMs has been reduced by several orders of magnitude compared to that (>0.5 T) in the previous schemes. Tuning the phase difference between the top and bottom superconductors can control the number and position of the MZMs. In addition, we account for the electrostatic potential in the superconductor/topological-insulator (SC/TI) interface through the self-consistent Schrödinger-Poisson calculation, which shows the experimental accessibility of our proposal. Our proposal only needs a small magnetic field of less than 10 mT and is robust against the chemical potential fluctuation, which makes the SC/TI/SC hybrid an ideal Majorana platform.
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Affiliation(s)
- Xiao-Hong Pan
- School of Physics and Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- Hubei Key Laboratory of Gravitation and Quantum Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- Wuhan Institute of Quantum Technology, Wuhan, Hubei 430074, China
| | - Li Chen
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Dong E Liu
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, 100084, China
| | - Fu-Chun Zhang
- Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Xin Liu
- School of Physics and Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- Hubei Key Laboratory of Gravitation and Quantum Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- Wuhan Institute of Quantum Technology, Wuhan, Hubei 430074, China
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9
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Matsuo S, Imoto T, Yokoyama T, Sato Y, Lindemann T, Gronin S, Gardner GC, Manfra MJ, Tarucha S. Phase engineering of anomalous Josephson effect derived from Andreev molecules. SCIENCE ADVANCES 2023; 9:eadj3698. [PMID: 38091387 PMCID: PMC10848717 DOI: 10.1126/sciadv.adj3698] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 11/14/2023] [Indexed: 02/12/2024]
Abstract
A Josephson junction (JJ) is a key device for developing superconducting circuits, wherein a supercurrent in the JJ is controlled by the phase difference between the two superconducting electrodes. When two JJs sharing one superconducting electrode are coherently coupled and form the Andreev molecules, a supercurrent of one JJ is expected to be nonlocally controlled by the phase difference of another JJ. Here, we evaluate the supercurrent in one of the coupled two JJs as a function of local and nonlocal phase differences. Consequently, the results exhibit that the nonlocal phase control generates a finite supercurrent even when the local phase difference is zero. In addition, an offset of the local phase difference giving the JJ ground state depends on the nonlocal phase difference. These features demonstrate the anomalous Josephson effect realized by the nonlocal phase control. Our results provide a useful concept for engineering superconducting devices such as phase batteries and dissipationless rectifiers.
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Affiliation(s)
- Sadashige Matsuo
- Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
| | - Takaya Imoto
- Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
- Department of Applied Physics, Tokyo University of Science, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Tomohiro Yokoyama
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yosuke Sato
- Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
| | - Tyler Lindemann
- Birck Nanotechnology Center, Purdue University,, West Lafayette, IN 47907, USA
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
| | - Sergei Gronin
- Birck Nanotechnology Center, Purdue University,, West Lafayette, IN 47907, USA
| | - Geoffrey C. Gardner
- Birck Nanotechnology Center, Purdue University,, West Lafayette, IN 47907, USA
| | - Michael J. Manfra
- Birck Nanotechnology Center, Purdue University,, West Lafayette, IN 47907, USA
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
- School of Materials Engineering, Purdue University, West Lafayette, IN 47907, USA
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Seigo Tarucha
- Center for Emergent Matter Science, RIKEN, Wako, Saitama 351-0198, Japan
- RIKEN Center for Quantum Computing, RIKEN, Wako, Saitama 351-0198, Japan
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10
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Matsuo S, Imoto T, Yokoyama T, Sato Y, Lindemann T, Gronin S, Gardner GC, Nakosai S, Tanaka Y, Manfra MJ, Tarucha S. Phase-dependent Andreev molecules and superconducting gap closing in coherently-coupled Josephson junctions. Nat Commun 2023; 14:8271. [PMID: 38092786 PMCID: PMC10719386 DOI: 10.1038/s41467-023-44111-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023] Open
Abstract
The Josephson junction (JJ) is an essential element of superconducting (SC) devices for both fundamental and applied physics. The short-range coherent coupling of two adjacent JJs forms Andreev molecule states (AMSs), which provide a new ingredient to engineer exotic SC phenomena such as topological SC states and Andreev qubits. Here we provide tunneling spectroscopy measurements on a device consisting of two electrically controllable planar JJs sharing a single SC electrode. We discover that Andreev spectra in the coupled JJ are highly modulated from those in the single JJs and possess phase-dependent AMS features reproduced in our numerical calculation. Notably, the SC gap closing due to the AMS formation is experimentally observed. Our results help in understanding SC transport derived from the AMS and promoting the use of AMS physics to engineer topological SC states and quantum information devices.
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Affiliation(s)
- Sadashige Matsuo
- Center for Emergent Matter Science, RIKEN, Saitama, 351-0198, Japan.
| | - Takaya Imoto
- Center for Emergent Matter Science, RIKEN, Saitama, 351-0198, Japan
- Department of Applied Physics, Tokyo University of Science, Tokyo, 162-8601, Japan
| | - Tomohiro Yokoyama
- Department of Materials Engineering Science, Osaka University, Osaka, 560-8531, Japan.
| | - Yosuke Sato
- Center for Emergent Matter Science, RIKEN, Saitama, 351-0198, Japan
| | - Tyler Lindemann
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana, IN, 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, IN, 47907, USA
| | - Sergei Gronin
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, IN, 47907, USA
| | - Geoffrey C Gardner
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, IN, 47907, USA
| | - Sho Nakosai
- Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
| | - Yukio Tanaka
- Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
| | - Michael J Manfra
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana, IN, 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, IN, 47907, USA
- School of Materials Engineering, Purdue University, West Lafayette, Indiana, IN, 47907, USA
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, IN, 47907, USA
| | - Seigo Tarucha
- Center for Emergent Matter Science, RIKEN, Saitama, 351-0198, Japan.
- RIKEN Center for Quantum Computing, RIKEN, Saitama, 351-0198, Japan.
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11
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Banerjee A, Geier M, Rahman MA, Thomas C, Wang T, Manfra MJ, Flensberg K, Marcus CM. Phase Asymmetry of Andreev Spectra from Cooper-Pair Momentum. PHYSICAL REVIEW LETTERS 2023; 131:196301. [PMID: 38000437 DOI: 10.1103/physrevlett.131.196301] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 08/10/2023] [Accepted: 10/16/2023] [Indexed: 11/26/2023]
Abstract
In analogy to conventional semiconductor diodes, the Josephson diode exhibits superconducting properties that are asymmetric in applied bias. The effect has been investigated in a number of systems recently, and requires a combination of broken time-reversal and inversion symmetries. We demonstrate a dual of the usual Josephson diode effect, a nonreciprocal response of Andreev bound states to a superconducting phase difference across the normal region of a superconductor-normal-superconductor Josephson junction, fabricated using an epitaxial InAs/Al heterostructure. Phase asymmetry of the subgap Andreev spectrum is absent in the absence of in-plane magnetic field and reaches a maximum at 0.15 T applied in the plane of the junction transverse to the current direction. We interpret the phase diode effect in this system as resulting from finite-momentum Cooper pairing due to orbital coupling to the in-plane magnetic field. At higher magnetic fields, we observe a sign reversal of the diode effect that appears together with a reopening of the spectral gap. Within our model, the sign reversal of the diode effect at higher fields is correlated with a topological phase transition that requires Zeeman and spin-orbit interactions in addition to orbital coupling.
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Affiliation(s)
- Abhishek Banerjee
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Max Geier
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Md Ahnaf Rahman
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Candice Thomas
- Department of Physics and Astronomy, and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Tian Wang
- Department of Physics and Astronomy, and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Michael J Manfra
- Department of Physics and Astronomy, and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
- School of Materials Engineering, and School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | - Karsten Flensberg
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Charles M Marcus
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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12
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Haxell DZ, Coraiola M, Sabonis D, Hinderling M, Ten Kate SC, Cheah E, Krizek F, Schott R, Wegscheider W, Belzig W, Cuevas JC, Nichele F. Microwave-induced conductance replicas in hybrid Josephson junctions without Floquet-Andreev states. Nat Commun 2023; 14:6798. [PMID: 37884490 PMCID: PMC10603169 DOI: 10.1038/s41467-023-42357-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 10/09/2023] [Indexed: 10/28/2023] Open
Abstract
Light-matter coupling allows control and engineering of complex quantum states. Here we investigate a hybrid superconducting-semiconducting Josephson junction subject to microwave irradiation by means of tunnelling spectroscopy of the Andreev bound state spectrum and measurements of the current-phase relation. For increasing microwave power, discrete levels in the tunnelling conductance develop into a series of equally spaced replicas, while the current-phase relation changes amplitude and skewness, and develops dips. Quantitative analysis of our results indicates that conductance replicas originate from photon assisted tunnelling of quasiparticles into Andreev bound states through the tunnelling barrier. Despite strong qualitative similarities with proposed signatures of Floquet-Andreev states, our study rules out this scenario. The distortion of the current-phase relation is explained by the interaction of Andreev bound states with microwave photons, including a non-equilibrium Andreev bound state occupation. The techniques outlined here establish a baseline to study light-matter coupling in hybrid nanostructures and distinguish photon assisted tunnelling from Floquet-Andreev states in mesoscopic devices.
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Affiliation(s)
| | - Marco Coraiola
- IBM Research Europe-Zurich, 8803, Rüschlikon, Switzerland
| | | | | | | | - Erik Cheah
- Laboratory for Solid State Physics, ETH Zürich, 8093, Zürich, Switzerland
| | - Filip Krizek
- IBM Research Europe-Zurich, 8803, Rüschlikon, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, 8093, Zürich, Switzerland
| | - Rüdiger Schott
- Laboratory for Solid State Physics, ETH Zürich, 8093, Zürich, Switzerland
| | - Werner Wegscheider
- Laboratory for Solid State Physics, ETH Zürich, 8093, Zürich, Switzerland
| | - Wolfgang Belzig
- Fachbereich Physik, Universität Konstanz, D-78457, Konstanz, Germany
| | - Juan Carlos Cuevas
- Fachbereich Physik, Universität Konstanz, D-78457, Konstanz, Germany
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049, Madrid, Spain
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13
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Xie YM, Lantagne-Hurtubise É, Young AF, Nadj-Perge S, Alicea J. Gate-Defined Topological Josephson Junctions in Bernal Bilayer Graphene. PHYSICAL REVIEW LETTERS 2023; 131:146601. [PMID: 37862641 DOI: 10.1103/physrevlett.131.146601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 09/07/2023] [Indexed: 10/22/2023]
Abstract
Recent experiments on Bernal bilayer graphene (BLG) deposited on monolayer WSe_{2} revealed robust, ultraclean superconductivity coexisting with sizable induced spin-orbit coupling. Here, we propose BLG/WSe_{2} as a platform to engineer gate-defined planar topological Josephson junctions, where the normal and superconducting regions descend from a common material. More precisely, we show that if superconductivity in BLG/WSe_{2} is gapped and emerges from a parent state with intervalley coherence, then Majorana zero-energy modes can form in the barrier region upon applying weak in-plane magnetic fields. Our results spotlight a potential pathway for "internally engineered" topological superconductivity that minimizes detrimental disorder and orbital-magnetic-field effects.
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Affiliation(s)
- Ying-Ming Xie
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - Étienne Lantagne-Hurtubise
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - Andrea F Young
- Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106, USA
| | - Stevan Nadj-Perge
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA
| | - Jason Alicea
- Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
- Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, California 91125, USA
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14
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Haxell D, Coraiola M, Sabonis D, Hinderling M, ten Kate SC, Cheah E, Krizek F, Schott R, Wegscheider W, Nichele F. Zeeman- and Orbital-Driven Phase Shifts in Planar Josephson Junctions. ACS NANO 2023; 17:18139-18147. [PMID: 37694539 PMCID: PMC10540266 DOI: 10.1021/acsnano.3c04957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/25/2023] [Indexed: 09/12/2023]
Abstract
We perform supercurrent and tunneling spectroscopy measurements on gate-tunable InAs/Al Josephson junctions (JJs) in an in-plane magnetic field and report on phase shifts in the current-phase relation measured with respect to an absolute phase reference. The impact of orbital effects is investigated by studying multiple devices with different superconducting lead sizes. At low fields, we observe gate-dependent phase shifts of up to φ0 = 0.5π, which are consistent with a Zeeman field coupling to highly transmissive Andreev bound states via Rashba spin-orbit interaction. A distinct phase shift emerges at larger fields, concomitant with a switching current minimum and the closing and reopening of the superconducting gap. These signatures of an induced phase transition, which might resemble a topological transition, scale with the superconducting lead size, demonstrating the crucial role of orbital effects. Our results elucidate the interplay of Zeeman, spin-orbit, and orbital effects in InAs/Al JJs, giving improved understanding of phase transitions in hybrid JJs and their applications in quantum computing and superconducting electronics.
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Affiliation(s)
| | - Marco Coraiola
- IBM
Research Europe−Zurich, 8803 Rüschlikon, Switzerland
| | | | | | | | - Erik Cheah
- Laboratory
for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Filip Krizek
- IBM
Research Europe−Zurich, 8803 Rüschlikon, Switzerland
- Laboratory
for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
- Institute
of Physics, Czech Academy of Sciences, 162 00 Prague, Czech Republic
| | - Rüdiger Schott
- Laboratory
for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
| | - Werner Wegscheider
- Laboratory
for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
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15
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Yan S, Su H, Pan D, Li W, Lyu Z, Chen M, Wu X, Lu L, Zhao J, Wang JY, Xu H. Supercurrent, Multiple Andreev Reflections and Shapiro Steps in InAs Nanosheet Josephson Junctions. NANO LETTERS 2023. [PMID: 37450769 DOI: 10.1021/acs.nanolett.3c01450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
We report an experimental study of proximity induced superconductivity in planar Josephson junction devices made from free-standing InAs nanosheets. The nanosheets are grown by molecular beam epitaxy, and the Josephson junction devices are fabricated by directly contacting the nanosheets with superconductor Al electrodes. The fabricated devices are explored by low-temperature carrier transport measurements. The measurements show that the devices exhibit a gate-tunable supercurrent, multiple Andreev reflections, and a good quality superconductor-semiconductor interface. The superconducting characteristics of the Josephson junctions are investigated at different magnetic fields and temperatures and are analyzed based on the Bardeen-Cooper-Schrieffer (BCS) theory. The measurements of the ac Josephson effect are also conducted under microwave radiations with different radiation powers and frequencies, and integer Shapiro steps are observed. Our work demonstrates that InAs nanosheet based hybrid devices are desired systems for investigating the forefront of physics, such as two-dimensional topological superconductivity.
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Affiliation(s)
- Shili Yan
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
| | - Haitian Su
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China
- Institute of Condensed Matter and Material Physics, School of Physics, Peking University, Beijing 100871, China
| | - Dong Pan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China
| | - Weijie Li
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Zhaozheng Lyu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Mo Chen
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
| | - Xingjun Wu
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
| | - Li Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China
| | - Ji-Yin Wang
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
| | - Hongqi Xu
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China
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16
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Yazdani A, von Oppen F, Halperin BI, Yacoby A. Hunting for Majoranas. Science 2023; 380:eade0850. [PMID: 37347870 DOI: 10.1126/science.ade0850] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 05/22/2023] [Indexed: 06/24/2023]
Abstract
Over the past decade, there have been considerable efforts to observe non-abelian quasiparticles in novel quantum materials and devices. These efforts are motivated by the goals of demonstrating quantum statistics of quasiparticles beyond those of fermions and bosons and of establishing the underlying science for the creation of topologically protected quantum bits. In this Review, we focus on efforts to create topological superconducting phases that host Majorana zero modes. We consider the lessons learned from existing experimental efforts, which are motivating both improvements to present platforms and the exploration of new approaches. Although the experimental detection of non-abelian quasiparticles remains challenging, the knowledge gained thus far and the opportunities ahead offer high potential for discovery and advances in this exciting area of quantum physics.
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Affiliation(s)
- Ali Yazdani
- Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, NJ 08540, USA
| | - Felix von Oppen
- Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | | | - Amir Yacoby
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
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17
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Cayao J. Exceptional degeneracies in non-Hermitian Rashba semiconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:254002. [PMID: 37021876 DOI: 10.1088/1361-648x/acc7e9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 03/27/2023] [Indexed: 06/19/2023]
Abstract
Exceptional points (EPs) are spectral degeneracies of non-Hermitian (NH) systems where eigenvalues and eigenvectors coalesce, inducing unique topological phases that have no counterpart in the Hermitian realm. Here we consider an NH system by coupling a two-dimensional semiconductor with Rashba spin-orbit coupling (SOC) to a ferromagnet lead and show the emergence of highly tunable EPs along rings in momentum space. Interestingly, these exceptional degeneracies are the endpoints of lines formed by the eigenvalue coalescence at finite real energy, resembling the bulk Fermi arcs commonly defined at zero real energy. We then show that an in-plane Zeeman field provides a way to control these exceptional degeneracies although higher values of non-Hermiticity are required in contrast to the zero Zeeman field regime. Furthermore, we find that the spin projections also coalescence at the exceptional degeneracies and can acquire larger values than in the Hermitian regime. Finally, we demonstrate that the exceptional degeneracies induce large spectral weights, which can be used as a signature for their detection. Our results thus reveal the potential of systems with Rashba SOC for realizing NH bulk phenomena.
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Affiliation(s)
- Jorge Cayao
- Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden
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18
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Banerjee A, Geier M, Rahman MA, Sanchez DS, Thomas C, Wang T, Manfra MJ, Flensberg K, Marcus CM. Control of Andreev Bound States Using Superconducting Phase Texture. PHYSICAL REVIEW LETTERS 2023; 130:116203. [PMID: 37001098 DOI: 10.1103/physrevlett.130.116203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 01/20/2023] [Indexed: 06/19/2023]
Abstract
Andreev bound states with opposite phase-inversion asymmetries are observed in local tunneling spectra at the two ends of a superconductor-semiconductor-superconductor planar Josephson junction in the presence of a perpendicular magnetic field, while the nonlocal spectra remain phase symmetric. Spectral signatures agree with a theoretical model, yielding a physical picture in which phase textures in superconducting leads localize and control the position of Andreev bound states in the junction, demonstrating a simple means of controlling the position and size of Andreev states within a planar junction.
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Affiliation(s)
- Abhishek Banerjee
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Max Geier
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - M Ahnaf Rahman
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Daniel S Sanchez
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Candice Thomas
- Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Tian Wang
- Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Michael J Manfra
- Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
- School of Materials Engineering and Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | - Karsten Flensberg
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Charles M Marcus
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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19
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Elfeky B, Cuozzo JJ, Lotfizadeh N, Schiela WF, Farzaneh SM, Strickland WM, Langone D, Rossi E, Shabani J. Evolution of 4π-Periodic Supercurrent in the Presence of an In-Plane Magnetic Field. ACS NANO 2023; 17:4650-4658. [PMID: 36800544 PMCID: PMC10018771 DOI: 10.1021/acsnano.2c10880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 02/15/2023] [Indexed: 06/18/2023]
Abstract
In the presence of a 4π-periodic contribution to the current phase relation, for example in topological Josephson junctions, odd Shapiro steps are expected to be missing. While missing odd Shapiro steps have been observed in several material systems and interpreted in the context of topological superconductivity, they have also been observed in topologically trivial junctions. Here, we study the evolution of such trivial missing odd Shapiro steps in Al-InAs junctions in the presence of an in-plane magnetic field Bθ. We find that the odd steps reappear at a crossover Bθ value, exhibiting an in-plane field angle anisotropy that depends on spin-orbit coupling effects. We interpret this behavior by theoretically analyzing the Andreev bound state spectrum and the transitions induced by the nonadiabatic dynamics of the junction and attribute the observed anisotropy to mode-to-mode coupling. Our results highlight the complex phenomenology of missing Shapiro steps and the underlying current phase relations in planar Josephson junctions designed to realize Majorana states.
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Affiliation(s)
- Bassel
Heiba Elfeky
- Center
for Quantum Information Physics, Department of Physics, New York University, New York, New York 10003, United States
| | - Joseph J. Cuozzo
- Department
of Physics, William & Mary, Williamsburg, Virginia 23187, United States
| | - Neda Lotfizadeh
- Center
for Quantum Information Physics, Department of Physics, New York University, New York, New York 10003, United States
| | - William F. Schiela
- Center
for Quantum Information Physics, Department of Physics, New York University, New York, New York 10003, United States
| | - Seyed M. Farzaneh
- Center
for Quantum Information Physics, Department of Physics, New York University, New York, New York 10003, United States
| | - William M. Strickland
- Center
for Quantum Information Physics, Department of Physics, New York University, New York, New York 10003, United States
| | - Dylan Langone
- Center
for Quantum Information Physics, Department of Physics, New York University, New York, New York 10003, United States
| | - Enrico Rossi
- Department
of Physics, William & Mary, Williamsburg, Virginia 23187, United States
| | - Javad Shabani
- Center
for Quantum Information Physics, Department of Physics, New York University, New York, New York 10003, United States
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20
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Ziesen A, Altland A, Egger R, Hassler F. Statistical Majorana Bound State Spectroscopy. PHYSICAL REVIEW LETTERS 2023; 130:106001. [PMID: 36962051 DOI: 10.1103/physrevlett.130.106001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
Tunnel spectroscopy data for the detection of Majorana bound states (MBS) is often criticized for its proneness to misinterpretation of genuine MBS with low-lying Andreev bound states. Here, we suggest a protocol removing this ambiguity by extending single shot measurements to sequences performed at varying system parameters. We demonstrate how such sampling, which we argue requires only moderate effort for current experimental platforms, resolves the statistics of Andreev side lobes, thus providing compelling evidence for the presence or absence of a Majorana center peak.
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Affiliation(s)
- Alexander Ziesen
- JARA Institute for Quantum Information, RWTH Aachen University, 52056 Aachen, Germany
| | - Alexander Altland
- Institut für Theoretische Physik, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
| | - Reinhold Egger
- Institut für Theoretische Physik, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
| | - Fabian Hassler
- JARA Institute for Quantum Information, RWTH Aachen University, 52056 Aachen, Germany
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21
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Banerjee A, Lesser O, Rahman MA, Thomas C, Wang T, Manfra MJ, Berg E, Oreg Y, Stern A, Marcus CM. Local and Nonlocal Transport Spectroscopy in Planar Josephson Junctions. PHYSICAL REVIEW LETTERS 2023; 130:096202. [PMID: 36930915 DOI: 10.1103/physrevlett.130.096202] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 01/11/2023] [Indexed: 06/18/2023]
Abstract
We report simultaneously acquired local and nonlocal transport spectroscopy in a phase-biased planar Josephson junction based on an epitaxial InAs-Al hybrid two-dimensional heterostructure. Quantum point contacts at the junction ends allow measurement of the 2×2 matrix of local and nonlocal tunneling conductances as a function of magnetic field along the junction, phase difference across the junction, and carrier density. A closing and reopening of a gap was observed in both the local and nonlocal tunneling spectra as a function of magnetic field. For particular tunings of junction density, gap reopenings were accompanied by zero-bias conductance peaks (ZBCPs) in local conductances. End-to-end correlation of gap reopening was strong, while correlation of local ZBCPs was weak. A model of the device, with disorder treated phenomenologically, shows comparable conductance matrix behavior associated with a topological phase transition. Phase dependence helps distinguish possible origins of the ZBCPs.
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Affiliation(s)
- A Banerjee
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - O Lesser
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel 76100
| | - M A Rahman
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - C Thomas
- Department of Physics and Astronomy, and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 USA
| | - T Wang
- Department of Physics and Astronomy, and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 USA
| | - M J Manfra
- Department of Physics and Astronomy, and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 USA
- School of Materials Engineering, and School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 USA
| | - E Berg
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Y Oreg
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Ady Stern
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel 76100
| | - C M Marcus
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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22
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Tam PM, Kane CL. Probing Fermi Sea Topology by Andreev State Transport. PHYSICAL REVIEW LETTERS 2023; 130:096301. [PMID: 36930895 DOI: 10.1103/physrevlett.130.096301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/16/2023] [Indexed: 06/18/2023]
Abstract
We show that the topology of the Fermi sea of a two-dimensional electron gas (2DEG) is reflected in the ballistic Landauer transport along a long and narrow Josephson π junction that proximitizes the 2DEG. The low-energy Andreev states bound to the junction are shown to exhibit a dispersion that is sensitive to the Euler characteristic of the Fermi sea (χ_{F}). We highlight two important relations: one connects the electron or hole nature of Andreev states to the convex or concave nature of Fermi surface critical points, and one relates these critical points to χ_{F}. We then argue that the transport of Andreev states leads to a quantized conductance that probes χ_{F}. An experiment is proposed to measure this effect, from which we predict an I-V characteristic that not only captures the topology of the Fermi sea in metals, but also resembles the rectification effect in diodes. Finally, we evaluate the feasibility of measuring this quantized response in graphene, InAs and HgTe 2DEGs.
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Affiliation(s)
- Pok Man Tam
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Charles L Kane
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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23
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Haxell DZ, Cheah E, Křížek F, Schott R, Ritter MF, Hinderling M, Belzig W, Bruder C, Wegscheider W, Riel H, Nichele F. Measurements of Phase Dynamics in Planar Josephson Junctions and SQUIDs. PHYSICAL REVIEW LETTERS 2023; 130:087002. [PMID: 36898094 DOI: 10.1103/physrevlett.130.087002] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 09/15/2022] [Accepted: 01/19/2023] [Indexed: 06/18/2023]
Abstract
We experimentally investigate the stochastic phase dynamics of planar Josephson junctions (JJs) and superconducting quantum interference devices (SQUIDs) defined in epitaxial InAs/Al heterostructures, and characterized by a large ratio of Josephson energy to charging energy. We observe a crossover from a regime of macroscopic quantum tunneling to one of phase diffusion as a function of temperature, where the transition temperature T^{*} is gate-tunable. The switching probability distributions are shown to be consistent with a small shunt capacitance and moderate damping, resulting in a switching current which is a small fraction of the critical current. Phase locking between two JJs leads to a difference in switching current between that of a JJ measured in isolation and that of the same JJ measured in an asymmetric SQUID loop. In the case of the loop, T^{*} is also tuned by a magnetic flux.
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Affiliation(s)
- D Z Haxell
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - E Cheah
- Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland
| | - F Křížek
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
- Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland
| | - R Schott
- Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland
| | - M F Ritter
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - M Hinderling
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - W Belzig
- Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany
| | - C Bruder
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - W Wegscheider
- Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland
| | - H Riel
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - F Nichele
- IBM Research Europe-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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24
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Dvir T, Wang G, van Loo N, Liu CX, Mazur GP, Bordin A, Ten Haaf SLD, Wang JY, van Driel D, Zatelli F, Li X, Malinowski FK, Gazibegovic S, Badawy G, Bakkers EPAM, Wimmer M, Kouwenhoven LP. Realization of a minimal Kitaev chain in coupled quantum dots. Nature 2023; 614:445-450. [PMID: 36792741 DOI: 10.1038/s41586-022-05585-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/22/2022] [Indexed: 02/17/2023]
Abstract
Majorana bound states constitute one of the simplest examples of emergent non-Abelian excitations in condensed matter physics. A toy model proposed by Kitaev shows that such states can arise at the ends of a spinless p-wave superconducting chain1. Practical proposals for its realization2,3 require coupling neighbouring quantum dots (QDs) in a chain through both electron tunnelling and crossed Andreev reflection4. Although both processes have been observed in semiconducting nanowires and carbon nanotubes5-8, crossed-Andreev interaction was neither easily tunable nor strong enough to induce coherent hybridization of dot states. Here we demonstrate the simultaneous presence of all necessary ingredients for an artificial Kitaev chain: two spin-polarized QDs in an InSb nanowire strongly coupled by both elastic co-tunnelling (ECT) and crossed Andreev reflection (CAR). We fine-tune this system to a sweet spot where a pair of poor man's Majorana states is predicted to appear. At this sweet spot, the transport characteristics satisfy the theoretical predictions for such a system, including pairwise correlation, zero charge and stability against local perturbations. Although the simple system presented here can be scaled to simulate a full Kitaev chain with an emergent topological order, it can also be used imminently to explore relevant physics related to non-Abelian anyons.
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Affiliation(s)
- Tom Dvir
- QuTech, Delft University of Technology, Delft, The Netherlands.
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
| | - Guanzhong Wang
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Nick van Loo
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Chun-Xiao Liu
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Grzegorz P Mazur
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Alberto Bordin
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Sebastiaan L D Ten Haaf
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Ji-Yin Wang
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - David van Driel
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Francesco Zatelli
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Xiang Li
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Filip K Malinowski
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Sasa Gazibegovic
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Ghada Badawy
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Erik P A M Bakkers
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Michael Wimmer
- QuTech, Delft University of Technology, Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Leo P Kouwenhoven
- QuTech, Delft University of Technology, Delft, The Netherlands.
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.
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25
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Hu LH, Wu X, Liu CX, Zhang RX. Competing Vortex Topologies in Iron-Based Superconductors. PHYSICAL REVIEW LETTERS 2022; 129:277001. [PMID: 36638298 DOI: 10.1103/physrevlett.129.277001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/07/2022] [Indexed: 06/17/2023]
Abstract
In this Letter, we establish a new theoretical paradigm for vortex Majorana physics in the recently discovered topological iron-based superconductors (TFeSCs). While TFeSCs are widely accepted as an exemplar of topological insulators (TIs) with intrinsic s-wave superconductivity, our theory implies that such a common belief could be oversimplified. Our main finding is that the normal-state bulk Dirac nodes, usually ignored in TI-based vortex Majorana theories for TFeSCs, will play a key role of determining the vortex state topology. In particular, the interplay between TI and Dirac nodal bands will lead to multiple competing topological phases for a superconducting vortex line in TFeSCs, including an unprecedented hybrid topological vortex state that carries both Majorana bound states and a gapless dispersion. Remarkably, this exotic hybrid vortex phase generally exists in the vortex phase diagram for our minimal model for TFeSCs and is directly relevant to TFeSC candidates such as LiFeAs. When the fourfold rotation symmetry is broken by vortex-line tilting or curving, the hybrid vortex gets topologically trivialized and becomes Majorana free, which could explain the puzzle of ubiquitous trivial vortices observed in LiFeAs. The origin of the Majorana signal in other TFeSC candidates such as FeTe_{x}Se_{1-x} and CaKFe_{4}As_{4} is also interpreted within our theory framework. Our theory sheds new light on theoretically understanding and experimentally engineering Majorana physics in high-temperature iron-based systems.
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Affiliation(s)
- Lun-Hui Hu
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Institute for Advanced Materials and Manufacturing, The University of Tennessee, Knoxville, Tennessee 37920, USA
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Xianxin Wu
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
- Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany
| | - Chao-Xing Liu
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Rui-Xing Zhang
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
- Institute for Advanced Materials and Manufacturing, The University of Tennessee, Knoxville, Tennessee 37920, USA
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, USA
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26
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Wang Z, Feng JJ, Huang Z, Niu Q. Transport Theory for Topological Josephson Junctions with a Majorana Qubit. PHYSICAL REVIEW LETTERS 2022; 129:257001. [PMID: 36608237 DOI: 10.1103/physrevlett.129.257001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 11/15/2022] [Indexed: 06/17/2023]
Abstract
We construct a semiclassical theory for the transport of topological Josephson junctions starting from a microscopic Hamiltonian that comprehensively includes the interplay among the Majorana qubit, the Josephson phase, and the dissipation process. With the path integral approach, we derive a set of semiclassical equations of motion that can be used to calculate the time evolution of the Josephson phase and the Majorana qubit. In the equations we reveal rich dynamical phenomena such as the qubit-induced charge pumping, the effective spin-orbit torque, and the Gilbert damping. We demonstrate the influence of these dynamical phenomena on the transport signatures of the junction. We apply the theory to study the Shapiro steps of the junction, and find the suppression of the first Shapiro step due to the dynamical feedback of the Majorana qubit.
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Affiliation(s)
- Zhi Wang
- School of Physics, Sun Yat-sen University, Guangzhou 510275, China
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Sun Yat-sen University, Guangzhou 510275, China
| | - Jia-Jin Feng
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Zhao Huang
- Texas Center for Superconductivity, University of Houston, Houston, Texas 77204, USA
| | - Qian Niu
- School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China
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27
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Moehle C, Rout PK, Jainandunsing NA, Kuiri D, Ke CT, Xiao D, Thomas C, Manfra MJ, Nowak MP, Goswami S. Controlling Andreev Bound States with the Magnetic Vector Potential. NANO LETTERS 2022; 22:8601-8607. [PMID: 36279222 PMCID: PMC9650727 DOI: 10.1021/acs.nanolett.2c03130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 10/16/2022] [Indexed: 06/16/2023]
Abstract
Tunneling spectroscopy measurements are often used to probe the energy spectrum of Andreev bound states (ABSs) in semiconductor-superconductor hybrids. Recently, this spectroscopy technique has been incorporated into planar Josephson junctions (JJs) formed in two-dimensional electron gases, a potential platform to engineer phase-controlled topological superconductivity. Here, we perform ABS spectroscopy at the two ends of planar JJs and study the effects of the magnetic vector potential on the ABS spectrum. We show that the local superconducting phase difference arising from the vector potential is equal in magnitude and opposite in sign at the two ends, in agreement with a model that assumes localized ABSs near the tunnel barriers. Complemented with microscopic simulations, our experiments demonstrate that the local phase difference can be used to estimate the relative position of localized ABSs separated by a few hundred nanometers.
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Affiliation(s)
- Christian
M. Moehle
- QuTech
and Kavli Institute of Nanoscience, Delft
University of Technology, 2600 GADelft, The Netherlands
| | - Prasanna K. Rout
- QuTech
and Kavli Institute of Nanoscience, Delft
University of Technology, 2600 GADelft, The Netherlands
| | - Nayan A. Jainandunsing
- QuTech
and Kavli Institute of Nanoscience, Delft
University of Technology, 2600 GADelft, The Netherlands
| | - Dibyendu Kuiri
- Academic
Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059Krakow, Poland
| | - Chung Ting Ke
- QuTech
and Kavli Institute of Nanoscience, Delft
University of Technology, 2600 GADelft, The Netherlands
| | - Di Xiao
- Department
of Physics and Astronomy, Purdue University, West Lafayette, Indiana47907, United States
| | - Candice Thomas
- Department
of Physics and Astronomy, Purdue University, West Lafayette, Indiana47907, United States
| | - Michael J. Manfra
- Department
of Physics and Astronomy, Purdue University, West Lafayette, Indiana47907, United States
- Elmore
School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana47907, United States
- School
of Materials Engineering, Purdue University, West Lafayette, Indiana47907, United States
- Microsoft
Quantum Lab West Lafayette, West
Lafayette, Indiana47907, United States
| | - Michał P. Nowak
- Academic
Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059Krakow, Poland
| | - Srijit Goswami
- QuTech
and Kavli Institute of Nanoscience, Delft
University of Technology, 2600 GADelft, The Netherlands
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28
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Fong KC. Graphene amplifier reaches the quantum limit. NATURE NANOTECHNOLOGY 2022; 17:1128-1129. [PMID: 36319754 DOI: 10.1038/s41565-022-01239-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
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29
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Graziano GV, Gupta M, Pendharkar M, Dong JT, Dempsey CP, Palmstrøm C, Pribiag VS. Selective control of conductance modes in multi-terminal Josephson junctions. Nat Commun 2022; 13:5933. [PMID: 36209199 PMCID: PMC9547902 DOI: 10.1038/s41467-022-33682-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 09/29/2022] [Indexed: 11/18/2022] Open
Abstract
The Andreev bound state spectra of multi-terminal Josephson junctions form an artificial band structure, which is predicted to host tunable topological phases under certain conditions. However, the number of conductance modes between the terminals of a multi-terminal Josephson junction must be few in order for this spectrum to be experimentally accessible. In this work, we employ a quantum point contact geometry in three-terminal Josephson devices to demonstrate independent control of conductance modes between each pair of terminals and access to the single-mode regime coexistent with the presence of superconducting coupling. These results establish a full platform on which to realize tunable Andreev bound state spectra in multi-terminal Josephson junctions.
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Affiliation(s)
- Gino V Graziano
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Mohit Gupta
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Mihir Pendharkar
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Jason T Dong
- Materials Department, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Connor P Dempsey
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Chris Palmstrøm
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- Materials Department, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- California NanoSystems Institute, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Vlad S Pribiag
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
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30
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Vacancy-engineered nodal-line semimetals. Sci Rep 2022; 12:14981. [PMID: 36056065 DOI: 10.1038/s41598-022-18519-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 08/09/2022] [Indexed: 11/08/2022] Open
Abstract
Symmetry-enforced nodal-line semimetals are immune to perturbations that preserve the underlying symmetries. This intrinsic robustness enables investigations of fundamental phenomena and applications utilizing diverse materials design techniques. The drawback of symmetry-enforced nodal-line semimetals is that the crossings of energy bands are constrained to symmetry-invariant momenta in the Brillouin zone. On the other end are accidental nodal-line semimetals whose band crossings, not being enforced by symmetry, are easily destroyed by perturbations. Some accidental nodal-line semimetals have, however, the advantage that their band crossings can occur in generic locations in the Brillouin zone, and thus can be repositioned to tailor material properties. We show that lattice engineering with periodic distributions of vacancies yields a hybrid type of nodal-line semimetals which possess symmetry-enforced nodal lines and accidental nodal lines, with the latter endowed with an enhanced robustness to perturbations. Both types of nodal lines are explained by a symmetry analysis of an effective model which captures the relevant characteristics of the proposed materials, and are verified by first-principles calculations of vacancy-engineered borophene polymorphs. Our findings offer an alternative path to relying on complicated compounds to design robust nodal-line semimetals; one can instead remove atoms from a common monoatomic material.
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31
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Hatefipour M, Cuozzo JJ, Kanter J, Strickland WM, Allemang CR, Lu TM, Rossi E, Shabani J. Induced Superconducting Pairing in Integer Quantum Hall Edge States. NANO LETTERS 2022; 22:6173-6178. [PMID: 35867620 DOI: 10.1021/acs.nanolett.2c01413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Indium arsenide (InAs) near surface quantum wells (QWs) are promising for the fabrication of semiconductor-superconductor heterostructures given that they allow for a strong hybridization between the two-dimensional states in the quantum well and the ones in the superconductor. In this work, we present results for InAs QWs in the quantum Hall regime placed in proximity of superconducting NbTiN. We observe a negative downstream resistance with a corresponding reduction of Hall (upstream) resistance, consistent with a very high Andreev conversion. We analyze the experimental data using the Landauer-Büttiker formalism, generalized to allow for Andreev reflection processes. We attribute the high efficiency of Andreev conversion in our devices to the large transparency of the InAs/NbTiN interface and the consequent strong hybridization of the QH edge modes with the states in the superconductor.
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Affiliation(s)
- Mehdi Hatefipour
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York 10003, United States
| | - Joseph J Cuozzo
- Department of Physics, William & Mary, Williamsburg, Virginia 23187, United States
| | - Jesse Kanter
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York 10003, United States
| | - William M Strickland
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York 10003, United States
| | | | - Tzu-Ming Lu
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87123, United States
| | - Enrico Rossi
- Department of Physics, William & Mary, Williamsburg, Virginia 23187, United States
| | - Javad Shabani
- Center for Quantum Phenomena, Department of Physics, New York University, New York, New York 10003, United States
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32
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Fan F, Chen Y, Pan D, Zhao J, Xu HQ. Electrically tunable spin-orbit interaction in an InAs nanosheet. NANOSCALE ADVANCES 2022; 4:2642-2648. [PMID: 36132279 PMCID: PMC9417834 DOI: 10.1039/d2na00143h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
We report an experimental study of the spin-orbit interaction (SOI) in an epitaxially grown free-standing InAs nanosheet in a dual-gate field-effect device. Gate-transfer characteristic measurements show that independent tuning of the carrier density in the nanosheet and the potential difference across the nanosheet can be efficiently achieved with the use of a dual gate. The quantum transport characteristics of the InAs nanosheet are investigated by magnetoconductance measurements at low temperatures. It is shown that the electron transport in the nanosheet can be tuned from the weak antilocalization to the weak localization and then back to the weak antilocalization regime with a voltage applied over the dual gate without a change in the carrier density. The spin-orbit length extracted from the magnetoconductance measurements at a constant carrier density exhibits a peak value at which the SOI of the Rashba type is suppressed and the spin relaxation due to the presence of an SOI of the Dresselhaus type in the nanosheet can be revealed. Energy band diagram simulations have also been carried out for the device under the experimental conditions and the physical insights into the experimental observations have been discussed in light of the results of simulations.
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Affiliation(s)
- Furong Fan
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University Beijing 100871 China
| | - Yuanjie Chen
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University Beijing 100871 China
| | - Dong Pan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences P.O. Box 912 Beijing 100083 China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences P.O. Box 912 Beijing 100083 China
| | - H Q Xu
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, School of Electronics, Peking University Beijing 100871 China
- Beijing Academy of Quantum Information Sciences Beijing 100193 China
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33
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Zhou T, Dartiailh MC, Sardashti K, Han JE, Matos-Abiague A, Shabani J, Žutić I. Fusion of Majorana bound states with mini-gate control in two-dimensional systems. Nat Commun 2022; 13:1738. [PMID: 35365644 PMCID: PMC8976011 DOI: 10.1038/s41467-022-29463-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 03/16/2022] [Indexed: 11/09/2022] Open
Abstract
A hallmark of topological superconductivity is the non-Abelian statistics of Majorana bound states (MBS), its chargeless zero-energy emergent quasiparticles. The resulting fractionalization of a single electron, stored nonlocally as a two spatially-separated MBS, provides a powerful platform for implementing fault-tolerant topological quantum computing. However, despite intensive efforts, experimental support for MBS remains indirect and does not probe their non-Abelian statistics. Here we propose how to overcome this obstacle in mini-gate controlled planar Josephson junctions (JJs) and demonstrate non-Abelian statistics through MBS fusion, detected by charge sensing using a quantum point contact, based on dynamical simulations. The feasibility of preparing, manipulating, and fusing MBS in two-dimensional (2D) systems is supported in our experiments which demonstrate the gate control of topological transition and superconducting properties with five mini gates in InAs/Al-based JJs. While we focus on this well-established platform, where the topological superconductivity was already experimentally detected, our proposal to identify elusive non-Abelian statistics motivates also further MBS studies in other gate-controlled 2D systems.
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Affiliation(s)
- Tong Zhou
- Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, 14260, USA.
| | - Matthieu C Dartiailh
- Center for Quantum Phenomena, Department of Physics, New York University, New York, NY, 10003, USA
| | - Kasra Sardashti
- Center for Quantum Phenomena, Department of Physics, New York University, New York, NY, 10003, USA
| | - Jong E Han
- Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, 14260, USA
| | - Alex Matos-Abiague
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, 48201, USA
| | - Javad Shabani
- Center for Quantum Phenomena, Department of Physics, New York University, New York, NY, 10003, USA
| | - Igor Žutić
- Department of Physics, University at Buffalo, State University of New York, Buffalo, NY, 14260, USA.
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34
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Telesio F, Carrega M, Cappelli G, Iorio A, Crippa A, Strambini E, Giazotto F, Serrano-Ruiz M, Peruzzini M, Heun S. Evidence of Josephson Coupling in a Few-Layer Black Phosphorus Planar Josephson Junction. ACS NANO 2022; 16:3538-3545. [PMID: 35099941 PMCID: PMC8945388 DOI: 10.1021/acsnano.1c09315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Setting up strong Josephson coupling in van der Waals materials in close proximity to superconductors offers several opportunities both to inspect fundamental physics and to develop cryogenic quantum technologies. Here we show evidence of Josephson coupling in a planar few-layer black phosphorus junction. The planar geometry allows us to probe the junction behavior by means of external gates, at different carrier concentrations. Clear signatures of Josephson coupling are demonstrated by measuring supercurrent flow through the junction at milli-Kelvin temperatures. Manifestation of a Fraunhofer pattern with a transverse magnetic field is also reported, confirming the Josephson coupling. These findings represent evidence of proximity Josephson coupling in a planar junction based on a van der Waals material beyond graphene and will expedite further studies, exploiting the peculiar properties of exfoliated black phosphorus thin flakes.
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Affiliation(s)
- Francesca Telesio
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | | | - Giulio Cappelli
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Andrea Iorio
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Alessandro Crippa
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Elia Strambini
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Francesco Giazotto
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | | | | | - Stefan Heun
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
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35
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Phan D, Senior J, Ghazaryan A, Hatefipour M, Strickland WM, Shabani J, Serbyn M, Higginbotham AP. Detecting Induced p±ip Pairing at the Al-InAs Interface with a Quantum Microwave Circuit. PHYSICAL REVIEW LETTERS 2022; 128:107701. [PMID: 35333085 DOI: 10.1103/physrevlett.128.107701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 12/15/2021] [Accepted: 01/31/2022] [Indexed: 06/14/2023]
Abstract
Superconductor-semiconductor hybrid devices are at the heart of several proposed approaches to quantum information processing, but their basic properties remain to be understood. We embed a two-dimensional Al-InAs hybrid system in a resonant microwave circuit, probing the breakdown of superconductivity due to an applied magnetic field. We find a fingerprint from the two-component nature of the hybrid system, and quantitatively compare with a theory that includes the contribution of intraband p±ip pairing in the InAs, as well as the emergence of Bogoliubov-Fermi surfaces due to magnetic field. Separately resolving the Al and InAs contributions allows us to determine the carrier density and mobility in the InAs.
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Affiliation(s)
- D Phan
- IST Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - J Senior
- IST Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - A Ghazaryan
- IST Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - M Hatefipour
- Department of Physics, New York University, New York, New York 10003, USA
| | - W M Strickland
- Department of Physics, New York University, New York, New York 10003, USA
| | - J Shabani
- Department of Physics, New York University, New York, New York 10003, USA
| | - M Serbyn
- IST Austria, Am Campus 1, 3400 Klosterneuburg, Austria
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36
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Wu X, Liu X, Thomale R, Liu CX. High- T c superconductor Fe(Se,Te) monolayer: an intrinsic, scalable and electrically tunable Majorana platform. Natl Sci Rev 2022; 9:nwab087. [PMID: 35308561 PMCID: PMC8924703 DOI: 10.1093/nsr/nwab087] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 04/25/2021] [Accepted: 04/25/2021] [Indexed: 11/30/2022] Open
Abstract
Iron-based superconductors have been identified as a novel platform for realizing Majorana zero modes (MZMs) without heterostructures, due to their intrinsic topological properties and high-T c superconductivity. In the two-dimensional limit, the FeTe1-x Se x monolayer, a topological band inversion has recently been experimentally observed. Here, we propose to create MZMs by applying an in-plane magnetic field to the FeTe1-x Se x monolayer and tuning the local chemical potential via electric gating. Owing to the anisotropic magnetic couplings on edges, an in-plane magnetic field drives the system into an intrinsic high-order topological superconductor phase with Majorana corner modes. Furthermore, MZMs can occur at the domain wall of chemical potentials at either one edge or certain type of tri-junction in the two-dimensional bulk. Our study not only reveals the FeTe1-x Se x monolayer as a promising Majorana platform with scalability and electrical tunability and within reach of contemporary experimental capability, but also provides a general principle to search for realistic realization of high-order topological superconductivity.
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Affiliation(s)
- Xianxin Wu
- Institut für Theoretische Physik und Astrophysik, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
| | - Xin Liu
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Ronny Thomale
- Institut für Theoretische Physik und Astrophysik, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
| | - Chao-Xing Liu
- Department of Physics, the Pennsylvania State University, University Park, PA 16802, USA
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37
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Topological Superconducting Transition Characterized by a Modified Real-Space-Pfaffian Method and Mobility Edges in a One-Dimensional Quasiperiodic Lattice. Symmetry (Basel) 2022. [DOI: 10.3390/sym14020371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
A modified real-space-Pfaffian method is applied to characterize the topological superconducting transition of a one-dimensional p-wave superconductor with quasiperiodic potentials. We found that the Majorana zero-energy mode exists in the topological non-trivial phase, and its spatial distribution is localized at ends of the system, whereas in the topological trivial phase, there is no Majorana zero mode. Furthermore, we numerically found that due to the competition between the localized quasi-disorder and the extended p-wave pairing, there are mobility edges in the energy spectra. Our theoretical work enriches the research on the quasiperiodic p-wave superconducting models.
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38
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Ril’ AI, Marenkin SF. Cadmium Arsenides: Structure, Synthesis of Bulk and Film Crystals, Magnetic and Electrical Properties (Review). RUSS J INORG CHEM+ 2022. [DOI: 10.1134/s0036023621140059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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39
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Moehle CM, Ke CT, Wang Q, Thomas C, Xiao D, Karwal S, Lodari M, van de Kerkhof V, Termaat R, Gardner GC, Scappucci G, Manfra MJ, Goswami S. InSbAs Two-Dimensional Electron Gases as a Platform for Topological Superconductivity. NANO LETTERS 2021; 21:9990-9996. [PMID: 34793173 DOI: 10.1021/acs.nanolett.1c03520] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Topological superconductivity can be engineered in semiconductors with strong spin-orbit interaction coupled to a superconductor. Experimental advances in this field have often been triggered by the development of new hybrid material systems. Among these, two-dimensional electron gases (2DEGs) are of particular interest due to their inherent design flexibility and scalability. Here, we discuss results on a 2D platform based on a ternary 2DEG (InSbAs) coupled to in situ grown aluminum. The spin-orbit coupling in these 2DEGs can be tuned with the As concentration, reaching values up to 400 meV Å, thus exceeding typical values measured in its binary constituents. In addition to a large Landé g-factor of ∼55 (comparable to that of InSb), we show that the clean superconductor-semiconductor interface leads to a hard induced superconducting gap. Using this new platform, we demonstrate the basic operation of phase-controllable Josephson junctions, superconducting islands, and quasi-1D systems, prototypical device geometries used to study Majorana zero modes.
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Affiliation(s)
- Christian M Moehle
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Chung Ting Ke
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Qingzhen Wang
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Candice Thomas
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Di Xiao
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Saurabh Karwal
- QuTech and Netherlands Organization for Applied Scientific Research (TNO), 2628 CK Delft, The Netherlands
| | - Mario Lodari
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Vincent van de Kerkhof
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Ruben Termaat
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Geoffrey C Gardner
- Microsoft Quantum Purdue, Purdue University, West Lafayette, Indiana 47907, United States
| | - Giordano Scappucci
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Michael J Manfra
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
- Microsoft Quantum Purdue, Purdue University, West Lafayette, Indiana 47907, United States
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Srijit Goswami
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
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40
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Majorana Zero Modes in Ferromagnetic Wires without Spin-Orbit Coupling. CONDENSED MATTER 2021. [DOI: 10.3390/condmat6040044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We present a novel controllable platform for engineering Majorana zero modes. The platform consists of a ferromagnetic metallic wire placed among conventional superconductors, which are in proximity to ferromagnetic insulators. We demonstrate that Majorana zero modes emerge localised at the edges of the ferromagnetic wire, due to the interplay of the applied supercurrents and the induced by proximity exchange fields with conventional superconductivity. Our mechanism does not rely on the pairing of helical fermions by combining conventional superconductivity with spin-orbit coupling, but rather exploits the misalignment between the magnetization of the ferromagnetic insulators and that of the ferromagnetic wire.
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41
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Elfeky BH, Lotfizadeh N, Schiela WF, Strickland WM, Dartiailh M, Sardashti K, Hatefipour M, Yu P, Pankratova N, Lee H, Manucharyan VE, Shabani J. Local Control of Supercurrent Density in Epitaxial Planar Josephson Junctions. NANO LETTERS 2021; 21:8274-8280. [PMID: 34570504 DOI: 10.1021/acs.nanolett.1c02771] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The critical current response to an applied out-of-plane magnetic field in a Josephson junction provides insight into the uniformity of its current distribution. In Josephson junctions with semiconducting weak links, the carrier density, and therefore the overall current distribution, can be modified electrostatically via metallic gates. Here, we show local control of the current distribution in an epitaxial Al-InAs Josephson junction equipped with five minigates. We demonstrate that not only can the junction width be electrostatically defined but also the current profile can be locally adjusted to form superconducting quantum interference devices. Our studies show enhanced edge conduction in such long junctions, which can be eliminated by minigates to create a uniform current distribution.
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Affiliation(s)
- Bassel Heiba Elfeky
- Department of Physics, New York University, New York, New York 10003, United States
| | - Neda Lotfizadeh
- Department of Physics, New York University, New York, New York 10003, United States
| | - William F Schiela
- Department of Physics, New York University, New York, New York 10003, United States
| | - William M Strickland
- Department of Physics, New York University, New York, New York 10003, United States
| | - Matthieu Dartiailh
- Department of Physics, New York University, New York, New York 10003, United States
| | - Kasra Sardashti
- Department of Physics, New York University, New York, New York 10003, United States
| | - Mehdi Hatefipour
- Department of Physics, New York University, New York, New York 10003, United States
| | - Peng Yu
- Department of Physics, New York University, New York, New York 10003, United States
| | - Natalia Pankratova
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, United States
| | - Hanho Lee
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, United States
| | - Vladimir E Manucharyan
- Department of Physics, Joint Quantum Institute, and Quantum Materials Center, University of Maryland, College Park, Maryland 20742, United States
| | - Javad Shabani
- Department of Physics, New York University, New York, New York 10003, United States
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42
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Hassan SA, Wu BH, Xu XF, Wang CR, Cao JC. Bending effect on the Majorana bound states in planar Josephson junctions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:385001. [PMID: 34171850 DOI: 10.1088/1361-648x/ac0ea7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/25/2021] [Indexed: 06/13/2023]
Abstract
We consider the bending effect on the formation of Majorana bound states (MBSs) in planar Josephson junctions where the normal stripe is tilted in a V shape. Our results show that the MBSs remain robust for moderate bending angles. Beyond some critical angles, the degradation of MBSs can be revealed by its eigenspectrum as well as the Majorana polarization (MP). Our results show that the parameter space of bending angle for robust MBSs can be significantly enlarged by tuning the superconducting phase difference across the Josephson junction. These findings suggest that the interplay of the junction geometry and the device parameters provides richer degree of freedom in designing topological superconducting devices for future applications. The MP analysis is an indispensable tool for characterizing the Majorana states.
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Affiliation(s)
- S A Hassan
- Department of Applied Physics, Donghua University, 2999 North Renmin Road, Shanghai, 201620, People's Republic of China
| | - B H Wu
- Department of Applied Physics, Donghua University, 2999 North Renmin Road, Shanghai, 201620, People's Republic of China
| | - X F Xu
- Department of Applied Physics, Donghua University, 2999 North Renmin Road, Shanghai, 201620, People's Republic of China
| | - C R Wang
- Department of Applied Physics, Donghua University, 2999 North Renmin Road, Shanghai, 201620, People's Republic of China
| | - J C Cao
- Key Laboratory of Terahertz Solid-State Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, People's Republic of China
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43
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Ramezani M, Sampaio IC, Watanabe K, Taniguchi T, Schönenberger C, Baumgartner A. Superconducting Contacts to a Monolayer Semiconductor. NANO LETTERS 2021; 21:5614-5619. [PMID: 34161104 PMCID: PMC8283752 DOI: 10.1021/acs.nanolett.1c00615] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 06/02/2021] [Indexed: 05/28/2023]
Abstract
We demonstrate superconducting vertical interconnect access (VIA) contacts to a monolayer of molybdenum disulfide (MoS2), a layered semiconductor with highly relevant electronic and optical properties. As a contact material we use MoRe, a superconductor with a high critical magnetic field and high critical temperature. The electron transport is mostly dominated by a single superconductor/normal conductor junction with a clear superconductor gap. In addition, we find MoS2 regions that are strongly coupled to the superconductor, resulting in resonant Andreev tunneling and junction-dependent gap characteristics, suggesting a superconducting proximity effect. Magnetoresistance measurements show that the bandstructure and the high intrinsic carrier mobility remain intact in the bulk of the MoS2. This type of VIA contact is applicable to a large variety of layered materials and superconducting contacts, opening up a path to monolayer semiconductors as a platform for superconducting hybrid devices.
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Affiliation(s)
- Mehdi Ramezani
- Department
of Physics, University of Basel, CH-4056, Basel, Switzerland
- Swiss
Nanoscience Institute, University of Basel, CH-4056, Basel, Switzerland
| | | | - Kenji Watanabe
- Research
Center for Functional Materials, National
Institute for Material Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - Takashi Taniguchi
- International
Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Christian Schönenberger
- Department
of Physics, University of Basel, CH-4056, Basel, Switzerland
- Swiss
Nanoscience Institute, University of Basel, CH-4056, Basel, Switzerland
| | - Andreas Baumgartner
- Department
of Physics, University of Basel, CH-4056, Basel, Switzerland
- Swiss
Nanoscience Institute, University of Basel, CH-4056, Basel, Switzerland
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44
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Wang Z, Cheng S, Liu X, Jiang H. Topological kink states in graphene. NANOTECHNOLOGY 2021; 32:402001. [PMID: 34161935 DOI: 10.1088/1361-6528/ac0dd8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
Due to the unique band structure, graphene exhibits a number of exotic electronic properties that have not been observed in other materials. Among them, it has been demonstrated that there exist the one-dimensional valley-polarized topological kink states localized in the vicinity of the domain wall of graphene systems, where a bulk energy gap opens due to the inversion symmetry breaking. Notably, the valley-momentum locking nature makes the topological kink states attractive to the property manipulation in valleytronics. This paper systematically reviews both the theoretical research and experimental progress on topological kink states in monolayer graphene, bilayer graphene and graphene-like classical wave systems. Besides, various applications of topological kink states, including the valley filter, current partition, current manipulation, Majorana zero modes and etc, are also introduced.
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Affiliation(s)
- Zibo Wang
- College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610068, People's Republic of China
- Center for Computational Sciences, Sichuan Normal University, Chengdu 610068, People's Republic of China
| | - Shuguang Cheng
- Department of Physics, Northwest University, Xi'an 710069, People's Republic of China
| | - Xiao Liu
- School of Physical Science and Technology, Soochow University, Suzhou 215006, People's Republic of China
| | - Hua Jiang
- School of Physical Science and Technology, Soochow University, Suzhou 215006, People's Republic of China
- Institute for Advanced Study of Soochow University, Suzhou 215006, People's Republic of China
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45
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Chiu SP, Tsuei CC, Yeh SS, Zhang FC, Kirchner S, Lin JJ. Observation of triplet superconductivity in CoSi 2/TiSi 2 heterostructures. SCIENCE ADVANCES 2021; 7:7/29/eabg6569. [PMID: 34272237 PMCID: PMC8284886 DOI: 10.1126/sciadv.abg6569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 06/03/2021] [Indexed: 05/22/2023]
Abstract
Unconventional superconductivity and, in particular, triplet superconductivity have been front and center of topological materials and quantum technology research. Here, we report our observation of triplet pairing in nonmagnetic CoSi2/TiSi2 heterostructures on silicon. CoSi2 undergoes a sharp superconducting transition at a critical temperature T c ≃ 1.5 K, while TiSi2 is a normal metal. We investigate conductance spectra of both two-terminal CoSi2/TiSi2 contact junctions and three-terminal T-shaped CoSi2/TiSi2 superconducting proximity structures. Below T c, we observe (i) a narrow zero-bias conductance peak on top of a broad hump, accompanied by two symmetric side dips in the contact junctions, (ii) a narrow zero-bias conductance peak in T-shaped structures, and (iii) hysteresis in the junction magnetoresistance. These three independent and complementary observations point to chiral p-wave pairing in CoSi2/TiSi2 heterostructures. The excellent fabrication compatibility of CoSi2 and TiSi2 with present-day silicon-based integrated-circuit technology suggests their potential use in scalable quantum-computing devices.
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Affiliation(s)
- Shao-Pin Chiu
- Institute of Physics and Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
| | - C C Tsuei
- IBM Thomas J. Watson Research Centers, Yorktown Heights, NY 10598, USA
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Sheng-Shiuan Yeh
- Institute of Physics and Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
- International College of Semiconductor Technology, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
| | - Fu-Chun Zhang
- Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Stefan Kirchner
- Zhejiang Institute of Modern Physics and Department of Physics, Zhejiang University, Hangzhou 310027, China.
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Zhejiang University, Hangzhou 310027, China
| | - Juhn-Jong Lin
- Institute of Physics and Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan.
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
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46
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Phase-induced topological superconductivity in a planar heterostructure. Proc Natl Acad Sci U S A 2021; 118:2107377118. [PMID: 34183403 DOI: 10.1073/pnas.2107377118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Topological superconductivity in quasi-one-dimensional systems is a novel phase of matter with possible implications for quantum computation. Despite years of effort, a definitive signature of this phase in experiments is still debated. A major cause of this ambiguity is the side effects of applying a magnetic field: induced in-gap states, vortices, and alignment issues. Here we propose a planar semiconductor-superconductor heterostructure as a platform for realizing topological superconductivity without applying a magnetic field to the two-dimensional electron gas hosting the topological state. Time-reversal symmetry is broken only by phase biasing the proximitizing superconductors, which can be achieved using extremely small fluxes or bias currents far from the quasi-one-dimensional channel. Our platform is based on interference between this phase biasing and the phase arising from strong spin-orbit coupling in closed electron trajectories. The principle is demonstrated analytically using a simple model, and then shown numerically for realistic devices. We show a robust topological phase diagram, as well as explicit wavefunctions of Majorana zero modes. We discuss experimental issues regarding the practical implementation of our proposal, establishing it as an accessible scheme with contemporary experimental techniques.
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47
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Liu F, Qu F, Žutić I, Xie S, Liu D, Fonseca ALA, Malard M. Robust Topological Nodal-Line Semimetals from Periodic Vacancies in Two-Dimensional Materials. J Phys Chem Lett 2021; 12:5710-5715. [PMID: 34128659 DOI: 10.1021/acs.jpclett.1c01249] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A nodal-line semimetal (NLSM) is suppressed in the presence of spin-orbit coupling unless it is protected by a nonsymmorphic symmetry. We show that two-dimensional (2D) materials can realize robust NLSMs when vacancies are introduced on the lattice. As a case study we investigate borophene, a boron honeycomb-like sheet. While the Dirac cones of pristine borophene are shown to be gapped out by spin-orbit coupling and by magnetic exchange, robust nodal lines (NLs) emerge in the spectrum when selected atoms are removed. We propose an effective 2D model and a symmetry analysis to demonstrate that these NLs are topological and protected by a nonsymmorphic glide plane. Our findings offer a paradigm shift to the design of NLSMs: instead of searching for nonsymmorphic materials, robust NLSMs may be realized simply by removing atoms from ordinary symmorphic crystals.
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Affiliation(s)
- F Liu
- Instituto de Física, Universidade de Brasília, Brasília-DF, Brazil
| | - F Qu
- Instituto de Física, Universidade de Brasília, Brasília-DF, Brazil
| | - I Žutić
- Department of Physics, University at Buffalo, the State University of New York, Buffalo, New York 14260, United States
| | - S Xie
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, China
| | - D Liu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, China
| | - A L A Fonseca
- Instituto de Física, Universidade de Brasília, Brasília-DF, Brazil
| | - M Malard
- Faculdade UnB Planaltina, Universidade de Brasília, Brasília-DF, Brazil
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48
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Qiu D, Gong C, Wang S, Zhang M, Yang C, Wang X, Xiong J. Recent Advances in 2D Superconductors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2006124. [PMID: 33768653 DOI: 10.1002/adma.202006124] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/22/2020] [Indexed: 06/12/2023]
Abstract
The emergence of superconductivity in 2D materials has attracted much attention and there has been rapid development in recent years because of their fruitful physical properties, such as high transition temperature (Tc ), continuous phase transition, and enhanced parallel critical magnetic field (Bc ). Tremendous efforts have been devoted to exploring different physical parameters to figure out the mechanisms behind the unexpected superconductivity phenomena, including adjusting the thickness of samples, fabricating various heterostructures, tuning the carrier density by electric field and chemical doping, and so on. Here, different types of 2D superconductivity with their unique characteristics are introduced, including the conventional Bardeen-Cooper-Schrieffer superconductivity in ultrathin films, high-Tc superconductivity in Fe-based and Cu-based 2D superconductors, unconventional superconductivity in newly discovered twist-angle bilayer graphene, superconductivity with enhanced Bc , and topological superconductivity. A perspective toward this field is then proposed based on academic knowledge from the recently reported literature. The aim is to provide researchers with a clear and comprehensive understanding about the newly developed 2D superconductivity and promote the development of this field much further.
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Affiliation(s)
- Dong Qiu
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Chuanhui Gong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - SiShuang Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Miao Zhang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Chao Yang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Xianfu Wang
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Jie Xiong
- State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, China
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49
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Pendharkar M, Zhang B, Wu H, Zarassi A, Zhang P, Dempsey CP, Lee JS, Harrington SD, Badawy G, Gazibegovic S, Op Het Veld RLM, Rossi M, Jung J, Chen AH, Verheijen MA, Hocevar M, Bakkers EPAM, Palmstrøm CJ, Frolov SM. Parity-preserving and magnetic field-resilient superconductivity in InSb nanowires with Sn shells. Science 2021; 372:508-511. [PMID: 33858990 DOI: 10.1126/science.aba5211] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/13/2021] [Indexed: 11/02/2022]
Abstract
Improving materials used to make qubits is crucial to further progress in quantum information processing. Of particular interest are semiconductor-superconductor heterostructures that are expected to form the basis of topological quantum computing. We grew semiconductor indium antimonide nanowires that were coated with shells of tin of uniform thickness. No interdiffusion was observed at the interface between Sn and InSb. Tunnel junctions were prepared by in situ shadowing. Despite the lack of lattice matching between Sn and InSb, a 15-nanometer-thick shell of tin was found to induce a hard superconducting gap, with superconductivity persisting in magnetic field up to 4 teslas. A small island of Sn-InSb exhibits the two-electron charging effect. These findings suggest a less restrictive approach to fabricating superconducting and topological quantum circuits.
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Affiliation(s)
- M Pendharkar
- Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
| | - B Zhang
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - H Wu
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - A Zarassi
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - P Zhang
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - C P Dempsey
- Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
| | - J S Lee
- California NanoSystems Institute, University of California, Santa Barbara, CA 93106, USA
| | - S D Harrington
- Materials Department, University of California, Santa Barbara, CA 93106, USA
| | - G Badawy
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - S Gazibegovic
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | | | - M Rossi
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - J Jung
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - A-H Chen
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - M A Verheijen
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - M Hocevar
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - E P A M Bakkers
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - C J Palmstrøm
- Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA.,California NanoSystems Institute, University of California, Santa Barbara, CA 93106, USA.,Materials Department, University of California, Santa Barbara, CA 93106, USA
| | - S M Frolov
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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Fragility of surface states in topological superfluid 3He. Nat Commun 2021; 12:1574. [PMID: 33692358 PMCID: PMC7946958 DOI: 10.1038/s41467-021-21831-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 01/28/2021] [Indexed: 11/23/2022] Open
Abstract
Superfluid 3He, with unconventional spin-triplet p-wave pairing, provides a model system for topological superconductors, which have attracted significant interest through potential applications in topologically protected quantum computing. In topological insulators and quantum Hall systems, the surface/edge states, arising from bulk-surface correspondence and the momentum space topology of the band structure, are robust. Here we demonstrate that in topological superfluids and superconductors the surface Andreev bound states, which depend on the momentum space topology of the emergent order parameter, are fragile with respect to the details of surface scattering. We confine superfluid 3He within a cavity of height D comparable to the Cooper pair diameter ξ0. We precisely determine the superfluid transition temperature Tc and the suppression of the superfluid energy gap, for different scattering conditions tuned in situ, and compare to the predictions of quasiclassical theory. We discover that surface magnetic scattering leads to unexpectedly large suppression of Tc, corresponding to an increased density of low energy bound states. Surface states in topological quantum matter are protected by their band structure. Here, on confined superfluid 3He as a model for topological superconductors, the authors report experimental evidence on the fragility of surface Andreev bound states with respect to the details of surface scattering.
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