1
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Górski G, Wójcik KP, Barański J, Weymann I, Domański T. Nonlocal correlations transmitted between quantum dots via short topological superconductor. Sci Rep 2024; 14:13848. [PMID: 38879622 PMCID: PMC11180147 DOI: 10.1038/s41598-024-64578-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 06/11/2024] [Indexed: 06/19/2024] Open
Abstract
We study the quasiparticle states and nonlocal correlations of a hybrid structure, comprising two quantum dots interconnected through a short-length topological superconducting nanowire hosting overlaping Majorana modes. We show that the hybridization between different components of this setup gives rise to the emergence of molecular states, which are responsible for nonlocal correlations. We inspect the resulting energy structure, focusing on the inter-dependence between the quasiparticles of individual quantum dots. We predict the existence of nonlocal effects, which could be accessed and probed by crossed Andreev reflection spectroscopy. Our study would be relevant to a recent experimental realization of the minimal Kitaev model [T. Dvir et al., Nature 614, 445 (2023) ], by considering its hybrid structure with side-attached quantum dots.
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Affiliation(s)
- G Górski
- Institute of Physics, College of Natural Sciences, University of Rzeszów, 35-310, Rzeszów, Poland.
| | - K P Wójcik
- Institute of Molecular Physics, Polish Academy of Sciences, 60-179, Poznań, Poland
| | - J Barański
- Polish Air Force University, ul. Dywizjonu 303 nr 35, 08-521, Dȩblin, Poland
| | - I Weymann
- Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University, 61-614, Poznań, Poland
| | - T Domański
- Institute of Physics, Maria Curie-Skłodowska University, 20-031, Lublin, Poland
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2
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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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3
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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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4
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Coraiola M, Haxell DZ, Sabonis D, Weisbrich H, Svetogorov AE, Hinderling M, Ten Kate SC, Cheah E, Krizek F, Schott R, Wegscheider W, Cuevas JC, Belzig W, Nichele F. Phase-engineering the Andreev band structure of a three-terminal Josephson junction. Nat Commun 2023; 14:6784. [PMID: 37880228 PMCID: PMC10600130 DOI: 10.1038/s41467-023-42356-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 10/09/2023] [Indexed: 10/27/2023] Open
Abstract
In hybrid Josephson junctions with three or more superconducting terminals coupled to a semiconducting region, Andreev bound states may form unconventional energy band structures, or Andreev matter, which are engineered by controlling superconducting phase differences. Here we report tunnelling spectroscopy measurements of three-terminal Josephson junctions realised in an InAs/Al heterostructure. The three terminals are connected to form two loops, enabling independent control over two phase differences and access to a synthetic Andreev band structure in the two-dimensional phase space. Our results demonstrate a phase-controlled Andreev molecule, originating from two discrete Andreev levels that spatially overlap and hybridise. Signatures of hybridisation are observed in the form of avoided crossings in the spectrum and band structure anisotropies in the phase space, all explained by a numerical model. Future extensions of this work could focus on addressing spin-resolved energy levels, ground state fermion parity transitions and Weyl bands in multiterminal geometries.
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Affiliation(s)
- Marco Coraiola
- IBM Research Europe-Zurich, 8803, Rüschlikon, Switzerland
| | | | | | - Hannes Weisbrich
- Fachbereich Physik, Universität Konstanz, D-78457, Konstanz, Germany
| | | | | | | | - 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
| | - Juan Carlos Cuevas
- Departamento de Física Teórica de la Materia Condensada and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049, Madrid, Spain
| | - Wolfgang Belzig
- Fachbereich Physik, Universität Konstanz, D-78457, Konstanz, Germany
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5
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Haxell D, Coraiola M, Hinderling M, ten Kate SC, Sabonis D, Svetogorov AE, Belzig W, Cheah E, Krizek F, Schott R, Wegscheider W, Nichele F. Demonstration of the Nonlocal Josephson Effect in Andreev Molecules. NANO LETTERS 2023; 23:7532-7538. [PMID: 37552598 PMCID: PMC10450812 DOI: 10.1021/acs.nanolett.3c02066] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/24/2023] [Indexed: 08/10/2023]
Abstract
We perform switching current measurements of planar Josephson junctions (JJs) coupled by a common superconducting electrode with independent control over the two superconducting phase differences. We observe an anomalous phase shift in the current-phase relation of a JJ as a function of gate voltage or phase difference in the second JJ. This demonstrates the nonlocal Josephson effect, and the implementation of a φ0-junction which is tunable both electrostatically and magnetically. The anomalous phase shift is larger for shorter distances between the JJs and vanishes for distances much longer than the superconducting coherence length. Results are consistent with the hybridization of Andreev bound states, leading to the formation of an Andreev molecule. Our devices constitute a realization of a tunable superconducting phase source and could enable new coupling schemes for hybrid quantum devices.
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Affiliation(s)
- Daniel
Z. Haxell
- IBM
Research Europe−Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Marco Coraiola
- IBM
Research Europe−Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Manuel Hinderling
- IBM
Research Europe−Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | | | - Deividas Sabonis
- IBM
Research Europe−Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | | | - Wolfgang Belzig
- Fachbereich
Physik, Universität Konstanz, D-78457 Konstanz, Germany
| | - Erik Cheah
- Solid
State Physics Laboratory, ETH Zürich, 8093 Zürich, Switzerland
| | - Filip Krizek
- Fachbereich
Physik, Universität Konstanz, D-78457 Konstanz, Germany
- Solid
State Physics Laboratory, ETH Zürich, 8093 Zürich, Switzerland
| | - Rüdiger Schott
- Solid
State Physics Laboratory, ETH Zürich, 8093 Zürich, Switzerland
| | | | - Fabrizio Nichele
- IBM
Research Europe−Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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6
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Lozano MS, Gómez VJ. Epitaxial growth of crystal phase quantum dots in III-V semiconductor nanowires. NANOSCALE ADVANCES 2023; 5:1890-1909. [PMID: 36998660 PMCID: PMC10044505 DOI: 10.1039/d2na00956k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 03/06/2023] [Indexed: 06/19/2023]
Abstract
Crystal phase quantum dots (QDs) are formed during the axial growth of III-V semiconductor nanowires (NWs) by stacking different crystal phases of the same material. In III-V semiconductor NWs, both zinc blende (ZB) and wurtzite (WZ) crystal phases can coexist. The band structure difference between both crystal phases can lead to quantum confinement. Thanks to the precise control in III-V semiconductor NW growth conditions and the deep knowledge on the epitaxial growth mechanisms, it is nowadays possible to control, down to the atomic level, the switching between crystal phases in NWs forming the so-called crystal phase NW-based QDs (NWQDs). The shape and size of the NW bridge the gap between QDs and the macroscopic world. This review is focused on crystal phase NWQDs based on III-V NWs obtained by the bottom-up vapor-liquid-solid (VLS) method and their optical and electronic properties. Crystal phase switching can be achieved in the axial direction. In contrast, in the core/shell growth, the difference in surface energies between different polytypes can enable selective shell growth. One reason for the very intense research in this field is motivated by their excellent optical and electronic properties both appealing for applications in nanophotonics and quantum technologies.
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Affiliation(s)
- Miguel Sinusia Lozano
- Nanophotonics Technology Center, Universitat Politècnica de València, Camino de Vera s/n Building 8F, 2a Floor 46022 Valencia Spain
| | - Víctor J Gómez
- Nanophotonics Technology Center, Universitat Politècnica de València, Camino de Vera s/n Building 8F, 2a Floor 46022 Valencia Spain
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7
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Potts H, Aspegren M, Debbarma R, Lehmann S, Thelander C. Large-bias spectroscopy of Yu-Shiba-Rusinov states in a double quantum dot. NANOTECHNOLOGY 2023; 34:135002. [PMID: 36595334 DOI: 10.1088/1361-6528/aca90e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
We have performed tunnel transport spectroscopy on a quantum dot (QD) molecule proximitized by a superconducting contact. In such a system, the scattering between QD spins and Bogoliubov quasiparticles leads to the formation of Yu-Shiba-Rusinov (YSR) states within the superconducting gap. In this work, we investigate interactions appearing when one- and two-electron spin states in a double-QD energetically align with the superconducting gap edge. We find that the inter-dot spin-triplet state interacts considerably stronger with the superconductor than the corresponding singlet, pointing to stronger screening. By forming a ring molecule with a significant orbital contribution to the effectiveg-factor, we observe interactions of all four spin-orbital one-electron states with the superconductor under a weak magnetic field.
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Affiliation(s)
- Heidi Potts
- Division of Solid State Physics and NanoLund, Lund University, SE-221 00 Lund, Sweden
| | - Markus Aspegren
- Division of Solid State Physics and NanoLund, Lund University, SE-221 00 Lund, Sweden
| | - Rousan Debbarma
- Division of Solid State Physics and NanoLund, Lund University, SE-221 00 Lund, Sweden
| | - Sebastian Lehmann
- Division of Solid State Physics and NanoLund, Lund University, SE-221 00 Lund, Sweden
| | - Claes Thelander
- Division of Solid State Physics and NanoLund, Lund University, SE-221 00 Lund, Sweden
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8
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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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9
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Zhang P, Wu H, Chen J, Khan SA, Krogstrup P, Pekker D, Frolov SM. Signatures of Andreev Blockade in a Double Quantum Dot Coupled to a Superconductor. PHYSICAL REVIEW LETTERS 2022; 128:046801. [PMID: 35148137 DOI: 10.1103/physrevlett.128.046801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 10/01/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
We investigate an electron transport blockade regime in which a spin triplet localized in the path of current is forbidden from entering a spin-singlet superconductor. To stabilize the triplet, a double quantum dot is created electrostatically near a superconducting Al lead in an InAs nanowire. The quantum dot closest to the normal lead exhibits Coulomb diamonds, and the dot closest to the superconducting lead exhibits Andreev bound states and an induced gap. The experimental observations compare favorably to a theoretical model of Andreev blockade, named so because the triplet double dot configuration suppresses Andreev reflections. Observed leakage currents can be accounted for by finite temperature. We observe the predicted quadruple level degeneracy points of high current and a periodic conductance pattern controlled by the occupation of the normal dot. Even-odd transport asymmetry is lifted with increased temperature and magnetic field. This blockade phenomenon can be used to study spin structure of superconductors. It may also find utility in quantum computing devices that use Andreev or Majorana states.
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Affiliation(s)
- Po Zhang
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Hao Wu
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Jun Chen
- Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Sabbir A Khan
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Peter Krogstrup
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - David Pekker
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Sergey M Frolov
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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10
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Kürtössy O, Scherübl Z, Fülöp G, Lukács IE, Kanne T, Nygård J, Makk P, Csonka S. Andreev Molecule in Parallel InAs Nanowires. NANO LETTERS 2021; 21:7929-7937. [PMID: 34538054 PMCID: PMC8517978 DOI: 10.1021/acs.nanolett.1c01956] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Indexed: 06/13/2023]
Abstract
Coupling individual atoms fundamentally changes the state of matter: electrons bound to atomic cores become delocalized turning an insulating state to a metallic one. A chain of atoms could lead to more exotic states if the tunneling takes place via the superconducting vacuum and can induce topologically protected excitations like Majorana or parafermions. Although coupling a single atom to a superconductor is well studied, the hybridization of two sites with individual tunability was not reported yet. The peculiar vacuum of the Bardeen-Cooper-Schrieffer (BCS) condensate opens the way to annihilate or generate two electrons from the bulk resulting in a so-called Andreev molecular state. By employing parallel nanowires with an Al shell, two artificial atoms were created at a minimal distance with an epitaxial superconducting link between. Hybridization via the BCS vacuum was observed and the spectrum of an Andreev molecule as a function of level positions was explored for the first time.
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Affiliation(s)
- Olivér Kürtössy
- Department
of Physics and Nanoelectronics “Momentum” Research Group
of the Hungarian Academy of Sciences, Budapest
University of Technology and Economics, Budafoki út 8, 1111 Budapest, Hungary
| | - Zoltán Scherübl
- Department
of Physics and Nanoelectronics “Momentum” Research Group
of the Hungarian Academy of Sciences, Budapest
University of Technology and Economics, Budafoki út 8, 1111 Budapest, Hungary
- University
of Grenoble Alpes, CEA, Grenoble INP, IRIG, PHELIQS, 38000 Grenoble, France
| | - Gergö Fülöp
- Department
of Physics and Nanoelectronics “Momentum” Research Group
of the Hungarian Academy of Sciences, Budapest
University of Technology and Economics, Budafoki út 8, 1111 Budapest, Hungary
| | - István Endre Lukács
- Center
for Energy Research, Institute of Technical
Physics and Material Science, Konkoly-Thege Miklós út 29-33, H-1121, Budapest, Hungary
| | - Thomas Kanne
- Center
for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jesper Nygård
- Center
for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Péter Makk
- Department
of Physics and Nanoelectronics “Momentum” Research Group
of the Hungarian Academy of Sciences, Budapest
University of Technology and Economics, Budafoki út 8, 1111 Budapest, Hungary
| | - Szabolcs Csonka
- Department
of Physics and Nanoelectronics “Momentum” Research Group
of the Hungarian Academy of Sciences, Budapest
University of Technology and Economics, Budafoki út 8, 1111 Budapest, Hungary
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11
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Kamlapure A, Cornils L, Žitko R, Valentyuk M, Mozara R, Pradhan S, Fransson J, Lichtenstein AI, Wiebe J, Wiesendanger R. Correlation of Yu-Shiba-Rusinov States and Kondo Resonances in Artificial Spin Arrays on an s-Wave Superconductor. NANO LETTERS 2021; 21:6748-6755. [PMID: 34351781 PMCID: PMC8392378 DOI: 10.1021/acs.nanolett.1c00387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 07/16/2021] [Indexed: 06/13/2023]
Abstract
Mutually interacting magnetic atoms coupled to a superconductor have gained enormous interest due to their potential for the realization of topological superconductivity. Individual magnetic impurities produce states within the superconducting energy gap known as Yu-Shiba-Rusinov (YSR) states. Here, using the tip of a scanning tunneling microscope, we artificially craft spin arrays consisting of an Fe adatom interacting with an assembly of interstitial Fe atoms (IFA) on a superconducting oxygen-reconstructed Ta(100) surface and show that the magnetic interaction between the adatom and the IFA assembly can be tuned by adjusting the number of IFAs in the assembly. The YSR state experiences a characteristic crossover in its energetic position and particle-hole spectral weight asymmetry when the Kondo resonance shows spectral depletion around the Fermi energy. By the help of slave-boson mean-field theory (SBMFT) and numerical renormalization group (NRG) calculations we associate the crossover with the transition from decoupled Kondo singlets to an antiferromagnetic ground state of the Fe adatom spin and the IFA assembly effective spin.
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Affiliation(s)
- Anand Kamlapure
- Department
of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - Lasse Cornils
- Department
of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - Rok Žitko
- Jožef
Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Faculty
of Mathematics and Physics, University of
Ljubljana, Jadranska
19, SI-1000 Ljubljana, Slovenia
| | - Maria Valentyuk
- Department
of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
- Department
of Theoretical Physics and Applied Mathematics, Ural Federal University, 19 Mira Street, Yekaterinburg 620002, Russia
| | - Roberto Mozara
- Department
of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - Saurabh Pradhan
- Department
of Physics and Astronomy, Uppsala University, P.O. Box 516, Uppsala SE-751 21, Sweden
| | - Jonas Fransson
- Department
of Physics and Astronomy, Uppsala University, P.O. Box 516, Uppsala SE-751 21, Sweden
| | - Alexander I. Lichtenstein
- Department
of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
- Department
of Theoretical Physics and Applied Mathematics, Ural Federal University, 19 Mira Street, Yekaterinburg 620002, Russia
| | - Jens Wiebe
- Department
of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - Roland Wiesendanger
- Department
of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
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12
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Demontis V, Zannier V, Sorba L, Rossella F. Surface Nano-Patterning for the Bottom-Up Growth of III-V Semiconductor Nanowire Ordered Arrays. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:2079. [PMID: 34443910 PMCID: PMC8398085 DOI: 10.3390/nano11082079] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 08/07/2021] [Accepted: 08/10/2021] [Indexed: 12/18/2022]
Abstract
Ordered arrays of vertically aligned semiconductor nanowires are regarded as promising candidates for the realization of all-dielectric metamaterials, artificial electromagnetic materials, whose properties can be engineered to enable new functions and enhanced device performances with respect to naturally existing materials. In this review we account for the recent progresses in substrate nanopatterning methods, strategies and approaches that overall constitute the preliminary step towards the bottom-up growth of arrays of vertically aligned semiconductor nanowires with a controlled location, size and morphology of each nanowire. While we focus specifically on III-V semiconductor nanowires, several concepts, mechanisms and conclusions reported in the manuscript can be invoked and are valid also for different nanowire materials.
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Affiliation(s)
- Valeria Demontis
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR, Piazza S. Silvestro 12, 56127 Pisa, Italy; (V.Z.); (L.S.)
| | - Valentina Zannier
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR, Piazza S. Silvestro 12, 56127 Pisa, Italy; (V.Z.); (L.S.)
| | - Lucia Sorba
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR, Piazza S. Silvestro 12, 56127 Pisa, Italy; (V.Z.); (L.S.)
| | - Francesco Rossella
- NEST, Scuola Normale Superiore and Istituto Nanoscienze CNR, Piazza S. Silvestro 12, 56127 Pisa, Italy; (V.Z.); (L.S.)
- Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Università di Modena e Reggio Emilia, Via Campi 213/A, 41125 Modena, Italy
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13
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Kanne T, Marnauza M, Olsteins D, Carrad DJ, Sestoft JE, de Bruijckere J, Zeng L, Johnson E, Olsson E, Grove-Rasmussen K, Nygård J. Epitaxial Pb on InAs nanowires for quantum devices. NATURE NANOTECHNOLOGY 2021; 16:776-781. [PMID: 33972757 DOI: 10.1038/s41565-021-00900-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Accepted: 03/11/2021] [Indexed: 05/21/2023]
Abstract
Semiconductor-superconductor hybrids are widely used to realize complex quantum phenomena, such as topological superconductivity and spins coupled to Cooper pairs. Accessing new, exotic regimes at high magnetic fields and increasing operating temperatures beyond the state-of-the-art requires new, epitaxially matched semiconductor-superconductor materials. One challenge is the generation of favourable conditions for heterostructural formation between materials with the desired properties. Here we harness an increased knowledge of metal-on-semiconductor growth to develop InAs nanowires with epitaxially matched, single-crystal, atomically flat Pb films with no axial grain boundaries. These highly ordered heterostructures have a critical temperature of 7 K and a superconducting gap of 1.25 meV, which remains hard at 8.5 T, and therefore they offer a parameter space more than twice as large as those of alternative semiconductor-superconductor hybrids. Additionally, InAs/Pb island devices exhibit magnetic field-driven transitions from a Cooper pair to single-electron charging, a prerequisite for use in topological quantum computation. Semiconductor-Pb hybrids potentially enable access to entirely new regimes for a number of different quantum systems.
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Affiliation(s)
- Thomas Kanne
- Center for Quantum Devices & Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
| | - Mikelis Marnauza
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Dags Olsteins
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Damon J Carrad
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Joachim E Sestoft
- Center for Quantum Devices & Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Joeri de Bruijckere
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | - Lunjie Zeng
- Department of Physics, Chalmers University of Technology, Gothenburg, Sweden
| | - Erik Johnson
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Eva Olsson
- Department of Physics, Chalmers University of Technology, Gothenburg, Sweden
| | - Kasper Grove-Rasmussen
- Center for Quantum Devices & Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Nygård
- Center for Quantum Devices & Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
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14
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Subgap dynamics of double quantum dot coupled between superconducting and normal leads. Sci Rep 2021; 11:11138. [PMID: 34045499 PMCID: PMC8160274 DOI: 10.1038/s41598-021-90080-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/30/2021] [Indexed: 11/17/2022] Open
Abstract
Dynamical processes induced by the external time-dependent fields can provide valuable insight into the characteristic energy scales of a given physical system. We investigate them here in a nanoscopic heterostructure, consisting of the double quantum dot coupled in series to the superconducting and the metallic reservoirs, analyzing its response to (i) abrupt bias voltage applied across the junction, (ii) sudden change of the energy levels, and imposed by (iii) their periodic driving. We explore subgap properties of this setup which are strictly related to the in-gap quasiparticles and discuss their signatures manifested in the time-dependent charge currents. The characteristic multi-mode oscillations, their beating patters and photon-assisted harmonics reveal a rich spectrum of dynamical features that might be important for designing the superconducting qubits.
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15
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Large spatial extension of the zero-energy Yu-Shiba-Rusinov state in a magnetic field. Nat Commun 2020; 11:1834. [PMID: 32286260 PMCID: PMC7156378 DOI: 10.1038/s41467-020-15322-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 03/03/2020] [Indexed: 11/30/2022] Open
Abstract
Various promising qubit concepts have been put forward recently based on engineered superconductor subgap states like Andreev bound states, Majorana zero modes or the Yu-Shiba-Rusinov (Shiba) states. The coupling of these subgap states via a superconductor strongly depends on their spatial extension and is an essential next step for future quantum technologies. Here we investigate the spatial extension of a Shiba state in a semiconductor quantum dot coupled to a superconductor. With detailed transport measurements and numerical renormalization group calculations we find a remarkable more than 50 nm extension of the zero energy Shiba state, much larger than the one observed in very recent scanning tunneling microscopy measurements. Moreover, we demonstrate that its spatial extension increases substantially in a magnetic field. Local magnetic moments coupled to superconductors can form subgap Yu-Shiba-Rusinov states. Here the authors show that Shiba states made with an InAs nanowire quantum dot have large spatial extent, which is beneficial for making Shiba chains that are predicted to host Majorana zero modes.
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16
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Damanet F, Mascarenhas E, Pekker D, Daley AJ. Controlling Quantum Transport via Dissipation Engineering. PHYSICAL REVIEW LETTERS 2019; 123:180402. [PMID: 31763915 DOI: 10.1103/physrevlett.123.180402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Indexed: 06/10/2023]
Abstract
Inspired by the microscopic control over dissipative processes in quantum optics and cold atoms, we develop an open-system framework to study dissipative control of transport in strongly interacting fermionic systems, relevant for both solid-state and cold-atom experiments. We show how subgap currents exhibiting multiple Andreev reflections-the stimulated transport of electrons in the presence of Cooper pairs-can be controlled via engineering of superconducting leads or superfluid atomic gases. Our approach incorporates dissipation within the channel, which is naturally occurring and can be engineered in cold gas experiments. This opens opportunities for engineering many phenomena with transport in strongly interacting systems. As examples, we consider particle loss and dephasing, and note different behavior for currents with different microscopic origin. We also show how to induce nonreciprocal electron and Cooper-pair currents.
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Affiliation(s)
- François Damanet
- Department of Physics and SUPA, University of Strathclyde, Glasgow G4 0NG, United Kingdom
| | - Eduardo Mascarenhas
- Department of Physics and SUPA, University of Strathclyde, Glasgow G4 0NG, United Kingdom
| | - David Pekker
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, Pennsylvania 15260, USA
| | - Andrew J Daley
- Department of Physics and SUPA, University of Strathclyde, Glasgow G4 0NG, United Kingdom
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17
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Badawy G, Gazibegovic S, Borsoi F, Heedt S, Wang CA, Koelling S, Verheijen MA, Kouwenhoven LP, Bakkers EPAM. High Mobility Stemless InSb Nanowires. NANO LETTERS 2019; 19:3575-3582. [PMID: 31094527 DOI: 10.1021/acs.nanolett.9b00545] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
High aspect-ratio InSb nanowires (NWs) of high chemical purity are sought for implementing advanced quantum devices. The growth of InSb NWs is challenging, generally requiring a stem of a foreign material for nucleation. Such a stem tends to limit the length of InSb NWs and its material becomes incorporated in the InSb segment. Here, we report on the growth of chemically pure InSb NWs tens of microns long. Using a selective-area mask in combination with gold as a catalyst allows complete omission of the stem, thus demonstrating that InSb NWs can grow directly from the substrate. The introduction of the selective-area mask gives rise to novel growth kinetics, demonstrating high growth rates and complete suppression of layer deposition on the mask for Sb-rich conditions. The crystal quality and chemical purity of these NWs is reflected in the significant enhancement of low-temperature electron mobility, yielding an average of 4.4 × 104 cm2/(V s), compared to previously studied InSb NWs grown on stems.
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Affiliation(s)
- Ghada Badawy
- Department of Applied Physics , Eindhoven University of Technology , 5600 MB Eindhoven , The Netherlands
| | - Sasa Gazibegovic
- Department of Applied Physics , Eindhoven University of Technology , 5600 MB Eindhoven , The Netherlands
- QuTech and Kavli Institute of NanoScience , Delft University of Technology , 2600 GA Delft , The Netherlands
| | - Francesco Borsoi
- QuTech and Kavli Institute of NanoScience , Delft University of Technology , 2600 GA Delft , The Netherlands
| | - Sebastian Heedt
- QuTech and Kavli Institute of NanoScience , Delft University of Technology , 2600 GA Delft , The Netherlands
| | - Chien-An Wang
- QuTech and Kavli Institute of NanoScience , Delft University of Technology , 2600 GA Delft , The Netherlands
| | - Sebastian Koelling
- QuTech and Kavli Institute of NanoScience , Delft University of Technology , 2600 GA Delft , The Netherlands
| | - Marcel A Verheijen
- Department of Applied Physics , Eindhoven University of Technology , 5600 MB Eindhoven , The Netherlands
- Eurofins Material Science Netherlands B.V. , High Tech Campus 11, 5656 AE Eindhoven , The Netherlands
| | - Leo P Kouwenhoven
- QuTech and Kavli Institute of NanoScience , Delft University of Technology , 2600 GA Delft , The Netherlands
- Microsoft Quantum Lab Delft , 2600 GA Delft , The Netherlands
| | - E P A M Bakkers
- Department of Applied Physics , Eindhoven University of Technology , 5600 MB Eindhoven , The Netherlands
- QuTech and Kavli Institute of NanoScience , Delft University of Technology , 2600 GA Delft , The Netherlands
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18
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Scherübl Z, Pályi A, Csonka S. Transport signatures of an Andreev molecule in a quantum dot-superconductor-quantum dot setup. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:363-378. [PMID: 30800576 PMCID: PMC6369982 DOI: 10.3762/bjnano.10.36] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 01/03/2019] [Indexed: 06/09/2023]
Abstract
Hybrid devices combining quantum dots with superconductors are important building blocks of conventional and topological quantum-information experiments. A requirement for the success of such experiments is to understand the various tunneling-induced non-local interaction mechanisms that are present in the devices, namely crossed Andreev reflection, elastic co-tunneling, and direct interdot tunneling. Here, we provide a theoretical study of a simple device that consists of two quantum dots and a superconductor tunnel-coupled to the dots, often called a Cooper-pair splitter. We study the three special cases where one of the three non-local mechanisms dominates, and calculate measurable ground-state properties, as well as the zero-bias and finite-bias differential conductance characterizing electron transport through this device. We describe how each non-local mechanism controls the measurable quantities, and thereby find experimental fingerprints that allow one to identify and quantify the dominant non-local mechanism using experimental data. Finally, we study the triplet blockade effect and the associated negative differential conductance in the Cooper-pair splitter, and show that they can arise regardless of the nature of the dominant non-local coupling mechanism. Our results should facilitate the characterization of hybrid devices, and their optimization for various quantum-information-related experiments and applications.
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Affiliation(s)
- Zoltán Scherübl
- Department of Physics and MTA-BME Momentum Nanoelectronics Research Group, Budapest University of Technology and Economics, Budafoki út 8., 1111 Budapest, Hungary
| | - András Pályi
- Department of Theoretical Physics and MTA-BME Exotic Quantum Phases ”Momentum” Research Group, Budapest University of Technology and Economics, 1111 Budapest, Hungary
| | - Szabolcs Csonka
- Department of Physics and MTA-BME Momentum Nanoelectronics Research Group, Budapest University of Technology and Economics, Budafoki út 8., 1111 Budapest, Hungary
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19
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Estrada Saldaña JC, Vekris A, Steffensen G, Žitko R, Krogstrup P, Paaske J, Grove-Rasmussen K, Nygård J. Supercurrent in a Double Quantum Dot. PHYSICAL REVIEW LETTERS 2018; 121:257701. [PMID: 30608792 DOI: 10.1103/physrevlett.121.257701] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Indexed: 06/09/2023]
Abstract
We demonstrate the Josephson effect in a serial double quantum dot defined in a nanowire with epitaxial superconducting leads. The supercurrent stability diagram adopts a honeycomb pattern. We observe sharp discontinuities in the magnitude of the critical current, I_{c}, as a function of dot occupation, related to doublet to singlet ground state transitions. Detuning of the energy levels offers a tuning knob for I_{c}, which attains a maximum at zero detuning. The consistency between experiment and theory indicates that our device is a faithful realization of the two-impurity Anderson model.
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Affiliation(s)
- J C Estrada Saldaña
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - A Vekris
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - G Steffensen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - R Žitko
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia
| | - P Krogstrup
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- Microsoft Quantum Materials Lab Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - J Paaske
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - K Grove-Rasmussen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - J Nygård
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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20
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Su Z, Zarassi A, Hsu JF, San-Jose P, Prada E, Aguado R, Lee EJH, Gazibegovic S, Op Het Veld RLM, Car D, Plissard SR, Hocevar M, Pendharkar M, Lee JS, Logan JA, Palmstrøm CJ, Bakkers EPAM, Frolov SM. Mirage Andreev Spectra Generated by Mesoscopic Leads in Nanowire Quantum Dots. PHYSICAL REVIEW LETTERS 2018; 121:127705. [PMID: 30296125 DOI: 10.1103/physrevlett.121.127705] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Indexed: 06/08/2023]
Abstract
We study transport mediated by Andreev bound states formed in InSb nanowire quantum dots. Two kinds of superconducting source and drain contacts are used: epitaxial Al/InSb devices exhibit a doubling of tunneling resonances, while, in NbTiN/InSb devices, Andreev spectra of the dot appear to be replicated multiple times at increasing source-drain bias voltages. In both devices, a mirage of a crowded spectrum is created. To describe the observations a model is developed that combines the effects of a soft induced gap and of additional Andreev bound states both in the quantum dot and in the finite regions of the nanowire adjacent to the quantum dot. Understanding of Andreev spectroscopy is important for the correct interpretation of Majorana experiments done on the same structures.
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Affiliation(s)
- Z Su
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - A Zarassi
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - J-F Hsu
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - P San-Jose
- Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Cantoblanco, 28049 Madrid, Spain
| | - E Prada
- Departamento de Fisica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolas Cabrera, Universidad Autonoma de Madrid, E-28049 Madrid, Spain
| | - R Aguado
- Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Cantoblanco, 28049 Madrid, Spain
| | - E J H Lee
- Departamento de Fisica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC) and Instituto Nicolas Cabrera, Universidad Autonoma de Madrid, E-28049 Madrid, Spain
| | - S Gazibegovic
- Eindhoven University of Technology, 5600 MB, Eindhoven, Netherlands
| | | | - D Car
- Eindhoven University of Technology, 5600 MB, Eindhoven, Netherlands
| | - S R Plissard
- LAAS CNRS, Université de Toulouse, 31031 Toulouse, France
| | - M Hocevar
- Univ. Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - M Pendharkar
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - J S Lee
- California NanoSystems Institute, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - J A Logan
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, USA
| | - C J Palmstrøm
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, California 93106, USA
- California NanoSystems Institute, University of California Santa Barbara, Santa Barbara, California 93106, USA
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, USA
| | - E P A M Bakkers
- Eindhoven University of Technology, 5600 MB, Eindhoven, Netherlands
| | - S M Frolov
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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21
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Yu-Shiba-Rusinov screening of spins in double quantum dots. Nat Commun 2018; 9:2376. [PMID: 29915280 PMCID: PMC6006160 DOI: 10.1038/s41467-018-04683-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 05/17/2018] [Indexed: 11/25/2022] Open
Abstract
A magnetic impurity coupled to a superconductor gives rise to a Yu–Shiba–Rusinov (YSR) state inside the superconducting energy gap. With increasing exchange coupling the excitation energy of this state eventually crosses zero and the system switches to a YSR ground state with bound quasiparticles screening the impurity spin by ħ/2. Here we explore indium arsenide (InAs) nanowire double quantum dots tunnel coupled to a superconductor and demonstrate YSR screening of spin-1/2 and spin-1 states. Gating the double dot through nine different charge states, we show that the honeycomb pattern of zero-bias conductance peaks, archetypal of double dots coupled to normal leads, is replaced by lines of zero-energy YSR states. These enclose regions of YSR-screened dot spins displaying distinctive spectral features, and their characteristic shape and topology change markedly with tunnel coupling strengths. We find excellent agreement with a simple zero-bandwidth approximation, and with numerical renormalization group calculations for the two-orbital Anderson model. Coupling superconductors to mesoscopic systems leads to unusual effects that could be exploited in new devices including topological quantum computers. Here the authors present a double quantum dot with a Yu–Shiba–Rusinov ground state arising from the interplay of Coulomb interactions and superconductivity.
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