1
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Tong C, Ginzel F, Kurzmann A, Garreis R, Ostertag L, Gerber JD, Huang WW, Watanabe K, Taniguchi T, Burkard G, Danon J, Ihn T, Ensslin K. Three-Carrier Spin Blockade and Coupling in Bilayer Graphene Double Quantum Dots. PHYSICAL REVIEW LETTERS 2024; 133:017001. [PMID: 39042804 DOI: 10.1103/physrevlett.133.017001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 04/08/2024] [Accepted: 05/19/2024] [Indexed: 07/25/2024]
Abstract
The spin degrees of freedom is crucial for the understanding of any condensed matter system. Knowledge of spin-mixing mechanisms is not only essential for successful control and manipulation of spin qubits, but also uncovers fundamental properties of investigated devices and material. For electrostatically defined bilayer graphene quantum dots, in which recent studies report spin-relaxation times T_{1} up to 50 ms with strong magnetic field dependence, we study spin-blockade phenomena at charge configuration (1,2)↔(0,3). We examine the dependence of the spin-blockade leakage current on interdot tunnel coupling and on the magnitude and orientation of externally applied magnetic field. In out-of-plane magnetic field, the observed zero-field current peak could arise from finite-temperature cotunneling with the leads; though involvement of additional spin- and valley-mixing mechanisms are necessary for explaining the persistent sharp side peaks observed. In in-plane magnetic field, we observe a zero-field current dip, attributed to the competition between the spin Zeeman effect and the Kane-Mele spin-orbit interaction. Details of the line shape of this current dip, however, suggest additional underlying mechanisms are at play.
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2
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Chakraborti H, Gorini C, Knothe A, Liu MH, Makk P, Parmentier FD, Perconte D, Richter K, Roulleau P, Sacépé B, Schönenberger C, Yang W. Electron wave and quantum optics in graphene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:393001. [PMID: 38697131 DOI: 10.1088/1361-648x/ad46bc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 05/01/2024] [Indexed: 05/04/2024]
Abstract
In the last decade, graphene has become an exciting platform for electron optical experiments, in some aspects superior to conventional two-dimensional electron gases (2DEGs). A major advantage, besides the ultra-large mobilities, is the fine control over the electrostatics, which gives the possibility of realising gap-less and compact p-n interfaces with high precision. The latter host non-trivial states,e.g., snake states in moderate magnetic fields, and serve as building blocks of complex electron interferometers. Thanks to the Dirac spectrum and its non-trivial Berry phase, the internal (valley and sublattice) degrees of freedom, and the possibility to tailor the band structure using proximity effects, such interferometers open up a completely new playground based on novel device architectures. In this review, we introduce the theoretical background of graphene electron optics, fabrication methods used to realise electron-optical devices, and techniques for corresponding numerical simulations. Based on this, we give a comprehensive review of ballistic transport experiments and simple building blocks of electron optical devices both in single and bilayer graphene, highlighting the novel physics that is brought in compared to conventional 2DEGs. After describing the different magnetic field regimes in graphene p-n junctions and nanostructures, we conclude by discussing the state of the art in graphene-based Mach-Zender and Fabry-Perot interferometers.
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Affiliation(s)
| | - Cosimo Gorini
- Université Paris-Saclay, CEA, CNRS, SPEC, 91191 Gif-sur-Yvette, France
| | - Angelika Knothe
- Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany
| | - Ming-Hao Liu
- Department of Physics and Center for Quantum Frontiers of Research and Technology (QFort), National Cheng Kung University, Tainan 70101, Taiwan
| | - Péter Makk
- Department of Physics, Institute of Physics, Budapest University of Technology and Economics, Műegyetem rkp. 3., Budapest H-1111, Hungary
- MTA-BME Correlated van der Waals Structures Momentum Research Group, Műegyetem rkp. 3., Budapest H-1111, Hungary
| | | | - David Perconte
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - Klaus Richter
- Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany
| | - Preden Roulleau
- Université Paris-Saclay, CEA, CNRS, SPEC, 91191 Gif-sur-Yvette, France
| | - Benjamin Sacépé
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | | | - Wenmin Yang
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
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3
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Hecker K, Banszerus L, Schäpers A, Möller S, Peters A, Icking E, Watanabe K, Taniguchi T, Volk C, Stampfer C. Coherent charge oscillations in a bilayer graphene double quantum dot. Nat Commun 2023; 14:7911. [PMID: 38036517 PMCID: PMC10689829 DOI: 10.1038/s41467-023-43541-3] [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: 03/14/2023] [Accepted: 11/13/2023] [Indexed: 12/02/2023] Open
Abstract
The coherent dynamics of a quantum mechanical two-level system passing through an anti-crossing of two energy levels can give rise to Landau-Zener-Stückelberg-Majorana (LZSM) interference. LZSM interference spectroscopy has proven to be a fruitful tool to investigate charge noise and charge decoherence in semiconductor quantum dots (QDs). Recently, bilayer graphene has developed as a promising platform to host highly tunable QDs potentially useful for hosting spin and valley qubits. So far, in this system no coherent oscillations have been observed and little is known about charge noise in this material. Here, we report coherent charge oscillations and [Formula: see text] charge decoherence times in a bilayer graphene double QD. The charge decoherence times are measured independently using LZSM interference and photon assisted tunneling. Both techniques yield [Formula: see text] average values in the range of 400-500 ps. The observation of charge coherence allows to study the origin and spectral distribution of charge noise in future experiments.
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Affiliation(s)
- K Hecker
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany.
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - L Banszerus
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - A Schäpers
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
| | - S Möller
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - A Peters
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
| | - E Icking
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - C Volk
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
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4
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Lubert-Perquel D, Acharya S, Johnson JC. Optically Addressing Exciton Spin and Pseudospin in Nanomaterials for Spintronics Applications. ACS APPLIED OPTICAL MATERIALS 2023; 1:1742-1760. [PMID: 38037653 PMCID: PMC10683369 DOI: 10.1021/acsaom.3c00299] [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: 08/28/2023] [Revised: 10/26/2023] [Accepted: 10/26/2023] [Indexed: 12/02/2023]
Abstract
Oriented exciton spins that can be generated and manipulated optically are of interest for a range of applications, including spintronics, quantum information science, and neuromorphic computing architectures. Although materials that host such excitons often lack practical coherence times for use on their own, strategic transduction of the magnetic information across interfaces can combine fast modulation with longer-term storage and readout. Several nanostructure systems have been put forward due to their interesting magneto-optical properties and their possible manipulation using circularly polarized light. These material systems are presented here, namely two-dimensional (2D) systems due to the unique spin-valley coupling properties and quantum dots for their exciton fine structure. 2D magnets are also discussed for their anisotropic spin behavior and extensive 2D magnetic states that are not yet fully understood but could pave the way for emergent techniques of magnetic control. This review also details the experimental and theoretical tools to measure and understand these systems along with a discussion on the progress of optical manipulation of spins and magnetic order transitions.
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Affiliation(s)
- Daphné Lubert-Perquel
- Materials, Chemical, and
Computational Science Directorate, National
Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Swagata Acharya
- Materials, Chemical, and
Computational Science Directorate, National
Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Justin C. Johnson
- Materials, Chemical, and
Computational Science Directorate, National
Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
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5
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Korkusinski M, Saleem Y, Dusko A, Miravet D, Hawrylak P. Spontaneous Spin and Valley Symmetry-Broken States of Interacting Massive Dirac Fermions in a Bilayer Graphene Quantum Dot. NANO LETTERS 2023; 23:7546-7551. [PMID: 37561956 DOI: 10.1021/acs.nanolett.3c02073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
We predict the existence of spontaneous spin and valley symmetry-broken states of interacting massive Dirac Fermions in a gated bilayer graphene quantum dot based on the exact diagonalization of the many-body Hamiltonian. The dot is defined by a vertical electric field and lateral gates, and its single-particle (SP) energies, wave functions, and Coulomb matrix elements are computed by using the atomistic tight-binding model. The effect of the Coulomb interaction is measured by the ratio of Coulomb elements to the SP level spacing. As we increase the interaction strength, we find the electrons in a series of spin and valley symmetry-broken phases with increasing valley and spin polarizations. The phase transitions result from the competition of the SP, exchange, and correlation energy scales. A phase diagram for N = 1-6 electrons is mapped out as a function of the Coulomb interaction strength.
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Affiliation(s)
- Marek Korkusinski
- Physics Department, University of Ottawa, Ottawa K1N6N5, Canada
- Security and Disruptive Technologies, National Research Council, Ottawa K1A0R6, Canada
| | - Yasser Saleem
- Physics Department, University of Ottawa, Ottawa K1N6N5, Canada
| | - Amintor Dusko
- Physics Department, University of Ottawa, Ottawa K1N6N5, Canada
| | - Daniel Miravet
- Physics Department, University of Ottawa, Ottawa K1N6N5, Canada
| | - Pawel Hawrylak
- Physics Department, University of Ottawa, Ottawa K1N6N5, Canada
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6
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Krishnan R, Biswas S, Hsueh YL, Ma H, Rahman R, Weber B. Spin-Valley Locking for In-Gap Quantum Dots in a MoS 2 Transistor. NANO LETTERS 2023. [PMID: 37363814 DOI: 10.1021/acs.nanolett.3c01779] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Spins confined to atomically thin semiconductors are being actively explored as quantum information carriers. In transition metal dichalcogenides (TMDCs), the hexagonal crystal lattice gives rise to an additional valley degree of freedom with spin-valley locking and potentially enhanced spin life and coherence times. However, realizing well-separated single-particle levels and achieving transparent electrical contact to address them has remained challenging. Here, we report well-defined spin states in a few-layer MoS2 transistor, characterized with a spectral resolution of ∼50 μeV at Tel = 150 mK. Ground state magnetospectroscopy confirms a finite Berry-curvature induced coupling of spin and valley, reflected in a pronounced Zeeman anisotropy, with a large out-of-plane g-factor of g⊥ ≃ 8. A finite in-plane g-factor (g∥ ≃ 0.55-0.8) allows us to quantify spin-valley locking and estimate the spin-orbit splitting 2ΔSO ∼ 100 μeV. The demonstration of spin-valley locking is an important milestone toward realizing spin-valley quantum bits.
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Affiliation(s)
- Radha Krishnan
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Sangram Biswas
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Yu-Ling Hsueh
- School of Physics, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Hongyang Ma
- School of Physics, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Rajib Rahman
- School of Physics, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Bent Weber
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
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7
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Banszerus L, Möller S, Hecker K, Icking E, Watanabe K, Taniguchi T, Hassler F, Volk C, Stampfer C. Particle-hole symmetry protects spin-valley blockade in graphene quantum dots. Nature 2023:10.1038/s41586-023-05953-5. [PMID: 37138084 DOI: 10.1038/s41586-023-05953-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 03/14/2023] [Indexed: 05/05/2023]
Abstract
Particle-hole symmetry plays an important role in the characterization of topological phases in solid-state systems1. It is found, for example, in free-fermion systems at half filling and it is closely related to the notion of antiparticles in relativistic field theories2. In the low-energy limit, graphene is a prime example of a gapless particle-hole symmetric system described by an effective Dirac equation3,4 in which topological phases can be understood by studying ways to open a gap by preserving (or breaking) symmetries5,6. An important example is the intrinsic Kane-Mele spin-orbit gap of graphene, which leads to a lifting of the spin-valley degeneracy and renders graphene a topological insulator in a quantum spin Hall phase7 while preserving particle-hole symmetry. Here we show that bilayer graphene allows the realization of electron-hole double quantum dots that exhibit near-perfect particle-hole symmetry, in which transport occurs via the creation and annihilation of single electron-hole pairs with opposite quantum numbers. Moreover, we show that particle-hole symmetric spin and valley textures lead to a protected single-particle spin-valley blockade. The latter will allow robust spin-to-charge and valley-to-charge conversion, which are essential for the operation of spin and valley qubits.
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Affiliation(s)
- L Banszerus
- JARA-FIT and 2nd Institute of Physics A, RWTH Aachen University, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
| | - S Möller
- JARA-FIT and 2nd Institute of Physics A, RWTH Aachen University, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
| | - K Hecker
- JARA-FIT and 2nd Institute of Physics A, RWTH Aachen University, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
| | - E Icking
- JARA-FIT and 2nd Institute of Physics A, RWTH Aachen University, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - F Hassler
- JARA-Institute for Quantum Information, RWTH Aachen University, Aachen, Germany
| | - C Volk
- JARA-FIT and 2nd Institute of Physics A, RWTH Aachen University, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics A, RWTH Aachen University, Aachen, Germany.
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich, Germany.
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8
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Saleem Y, Sadecka K, Korkusinski M, Miravet D, Dusko A, Hawrylak P. Theory of Excitons in Gated Bilayer Graphene Quantum Dots. NANO LETTERS 2023; 23:2998-3004. [PMID: 36962005 DOI: 10.1021/acs.nanolett.3c00406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We present a theory of excitons in gated bilayer graphene (BLG) quantum dots (QDs). Electrical gating of BLG opens an energy gap, turning this material into an electrically tunable semiconductor. Unlike in laterally gated semiconductor QDs, where electrons are attracted and holes repelled, we show here that lateral structuring of metallic gates results in a gated lateral QD confining both electrons and holes. Using an accurate atomistic approach and exact diagonalization tools, we describe strongly interacting electrons and holes forming an electrically tunable exciton. We find these excitons to be different from those found in semiconductor QDs and nanocrystals, with exciton energy tunable by voltage from the terahertz to far infrared (FIR) range. The conservation of spin, valley, and orbital angular momentum results in an exciton fine structure with a band of dark low-energy states, making this system a promising candidate for storage, detection and emission of photons in the terahertz range.
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Affiliation(s)
- Yasser Saleem
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
| | - Katarzyna Sadecka
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
- Institute of Theoretical Physics, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Marek Korkusinski
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
- Security and Disruptive Technologies, National Research Council, Ottawa K1A0R6, Canada
| | - Daniel Miravet
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
| | - Amintor Dusko
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
| | - Pawel Hawrylak
- Department of Physics, University of Ottawa, Ottawa K1N6N5, Canada
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9
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Pang J, Peng S, Hou C, Zhao H, Fan Y, Ye C, Zhang N, Wang T, Cao Y, Zhou W, Sun D, Wang K, Rümmeli MH, Liu H, Cuniberti G. Applications of Graphene in Five Senses, Nervous System, and Artificial Muscles. ACS Sens 2023; 8:482-514. [PMID: 36656873 DOI: 10.1021/acssensors.2c02790] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Graphene remains of great interest in biomedical applications because of biocompatibility. Diseases relating to human senses interfere with life satisfaction and happiness. Therefore, the restoration by artificial organs or sensory devices may bring a bright future by the recovery of senses in patients. In this review, we update the most recent progress in graphene based sensors for mimicking human senses such as artificial retina for image sensors, artificial eardrums, gas sensors, chemical sensors, and tactile sensors. The brain-like processors are discussed based on conventional transistors as well as memristor related neuromorphic computing. The brain-machine interface is introduced for providing a single pathway. Besides, the artificial muscles based on graphene are summarized in the means of actuators in order to react to the physical world. Future opportunities remain for elevating the performances of human-like sensors and their clinical applications.
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Affiliation(s)
- Jinbo Pang
- Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Jinan 250022, China
| | - Songang Peng
- High-Frequency High-Voltage Device and Integrated Circuits R&D Center and Key Laboratory of Microelectronic Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Chongyang Hou
- Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Jinan 250022, China
| | - Hongbin Zhao
- State Key Laboratory of Advanced Materials for Smart Sensing, GRINM Group Co. Ltd., Xinwai Street 2, Beijing 100088, People's Republic of China
| | - Yingju Fan
- School of Chemistry and Chemical Engineering, University of Jinan, Shandong, Jinan 250022, China
| | - Chen Ye
- School of Chemistry and Chemical Engineering, University of Jinan, Shandong, Jinan 250022, China
| | - Nuo Zhang
- School of Chemistry and Chemical Engineering, University of Jinan, Shandong, Jinan 250022, China
| | - Ting Wang
- State Key Laboratory of Biobased Material and Green Papermaking and People's Republic of China School of Bioengineering, Qilu University of Technology, Shandong Academy of Sciences, No. 3501 Daxue Road, Jinan 250353, People's Republic of China
| | - Yu Cao
- Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology (Ministry of Education) and School of Electrical Engineering, Northeast Electric Power University, Jilin 132012, China
| | - Weijia Zhou
- Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Jinan 250022, China
| | - Ding Sun
- School of Electrical and Computer Engineering, Jilin Jianzhu University, Changchun 130118, P. R. China
| | - Kai Wang
- School of Electrical Engineering, Weihai Innovation Research Institute, Qingdao University, Qingdao 266000, China
| | - Mark H Rümmeli
- Leibniz Institute for Solid State and Materials Research Dresden, Dresden, D-01171, Germany.,College of Energy, Soochow Institute for Energy and Materials Innovations, and Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou 215006, China.,Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie Sklodowskiej 34, Zabrze 41-819, Poland.,Institute for Complex Materials, IFW Dresden, 20 Helmholtz Strasse, Dresden 01069, Germany.,Center for Energy and Environmental Technologies, VŠB-Technical University of Ostrava, 17. Listopadu 15, Ostrava 708 33, Czech Republic
| | - Hong Liu
- Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong, Institute for Advanced Interdisciplinary Research (iAIR), University of Jinan, Jinan 250022, China.,State Key Laboratory of Crystal Materials, Center of Bio & Micro/Nano Functional Materials, Shandong University, 27 Shandanan Road, Jinan 250100, China
| | - Gianaurelio Cuniberti
- Institute for Materials Science and Max Bergmann Center of Biomaterials and Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden 01069, Germany
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10
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Spin relaxation in a single-electron graphene quantum dot. Nat Commun 2022; 13:3637. [PMID: 35752620 PMCID: PMC9233672 DOI: 10.1038/s41467-022-31231-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 06/08/2022] [Indexed: 12/02/2022] Open
Abstract
The relaxation time of a single-electron spin is an important parameter for solid-state spin qubits, as it directly limits the lifetime of the encoded information. Thanks to the low spin-orbit interaction and low hyperfine coupling, graphene and bilayer graphene (BLG) have long been considered promising platforms for spin qubits. Only recently, it has become possible to control single-electrons in BLG quantum dots (QDs) and to understand their spin-valley texture, while the relaxation dynamics have remained mostly unexplored. Here, we report spin relaxation times (T1) of single-electron states in BLG QDs. Using pulsed-gate spectroscopy, we extract relaxation times exceeding 200 μs at a magnetic field of 1.9 T. The T1 values show a strong dependence on the spin splitting, promising even longer T1 at lower magnetic fields, where our measurements are limited by the signal-to-noise ratio. The relaxation times are more than two orders of magnitude larger than those previously reported for carbon-based QDs, suggesting that graphene is a potentially promising host material for scalable spin qubits. Graphene has long been considered to be a promising host for spin qubits, however a demonstration of long spin relaxation times for a potential qubit has been lacking. Here, the authors report the electrical measurement of the single-electron spin relaxation time exceeding 200 μs in a bilayer graphene quantum dot.
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11
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Wang Q, Zhu B, Han Y, Yang X, Xu Y, Cheng Y, Liu T, Wu J, Li S, Ding L, Bai J, Niu Y. Metal ions mediated carbon dots nanoprobe for fluorescent turn-on sensing of N-acetyl-L-cysteine. LUMINESCENCE 2022; 37:1267-1274. [PMID: 35608368 DOI: 10.1002/bio.4292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 05/19/2022] [Accepted: 05/20/2022] [Indexed: 11/06/2022]
Abstract
Carbon dots (CDs) was facilely synthesized from aspartic acid through a pyrolysis method in this work. Based on their favorable fluorescence property, CDs was utilized to design a metal ions-mediated fluorescent probe for N-acetyl-L-cysteine (NAC) detection. The fluorescence intensity of CDs was firstly quenched by manganese ion (Mn2+ ) through static quenching effect and subsequently restored by NAC via the combination with Mn2+ owing to the coordination effect. Therefore, the fluorescent turn-on sensing of NAC was actuated based on the fluorescence quenching stimulated by Mn2+ and recovery induced by coordination. The fluorescence recovery efficiencies showed a proportional range to the concentration of NAC in the range of 0.04-5 mmol L-1 and the detection limit was 0.03 mmol L-1 . Further, this metal ions-mediated fluorescent nanoprobe was applied to human urine sample detection and the standard recovery rates were located in the range of 97.62-102.34 %. It was the first time that Mn2+ was used to construct fluorescent nanoprobe for NAC. Compared to other heavy metal ions, Mn2+ with good biosecurity prevented the risk of application, which made the nanoprobe green and bio-practical. The facile synthesis of CDs and novel metal ions-mediated sensing mode made it a promising method for pharmaceutical analysis.
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Affiliation(s)
- Qi Wang
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
| | - Bin Zhu
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
| | - Yejiao Han
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
| | - Xin Yang
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
| | - Yanan Xu
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
| | - Ying Cheng
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
| | - Taotao Liu
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
| | - Jiana Wu
- Department of Environment and Safety Engineering, Taiyuan Institute of Technology, Taiyuan, China
| | - Shengling Li
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
| | - Lifeng Ding
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
| | - Jingjing Bai
- Department of Materials Engineering, Taiyuan Institute of Technology, Taiyuan, China
| | - Yulan Niu
- Chemistry & Chemical Engineering Department, Taiyuan Institute of Technology, Taiyuan, China
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12
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Tong C, Kurzmann A, Garreis R, Huang WW, Jele S, Eich M, Ginzburg L, Mittag C, Watanabe K, Taniguchi T, Ensslin K, Ihn T. Pauli Blockade of Tunable Two-Electron Spin and Valley States in Graphene Quantum Dots. PHYSICAL REVIEW LETTERS 2022; 128:067702. [PMID: 35213193 DOI: 10.1103/physrevlett.128.067702] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 11/23/2021] [Accepted: 01/10/2022] [Indexed: 05/21/2023]
Abstract
Pauli blockade mechanisms-whereby carrier transport through quantum dots (QD) is blocked due to selection rules even when energetically allowed-are a direct manifestation of the Pauli exclusion principle, as well as a key mechanism for manipulating and reading out spin qubits. The Pauli spin blockade is well established for systems such as GaAs QDs, but is to be further explored for systems with additional degrees of freedom, such as the valley quantum numbers in carbon-based materials or silicon. Here we report experiments on coupled bilayer graphene double quantum dots, in which the spin and valley states are precisely controlled, enabling the observation of the two-electron combined blockade physics. We demonstrate that the doubly occupied single dot switches between two different ground states with gate and magnetic-field tuning, allowing for the switching of selection rules: with a spin-triplet-valley-singlet ground state, valley blockade is observed; and with the spin-singlet-valley-triplet ground state, robust spin blockade is shown.
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Affiliation(s)
- Chuyao Tong
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Annika Kurzmann
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Rebekka Garreis
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Wei Wister Huang
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Samuel Jele
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Marius Eich
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Lev Ginzburg
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
| | | | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials 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
| | - Klaus Ensslin
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Thomas Ihn
- Solid State Physics Laboratory, ETH Zurich, CH-8093 Zurich, Switzerland
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13
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Alfieri A, Anantharaman SB, Zhang H, Jariwala D. Nanomaterials for Quantum Information Science and Engineering. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022:e2109621. [PMID: 35139247 DOI: 10.1002/adma.202109621] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 02/04/2022] [Indexed: 06/14/2023]
Abstract
Quantum information science and engineering (QISE)-which entails the use of quantum mechanical states for information processing, communications, and sensing-and the area of nanoscience and nanotechnology have dominated condensed matter physics and materials science research in the 21st century. Solid-state devices for QISE have, to this point, predominantly been designed with bulk materials as their constituents. This review considers how nanomaterials (i.e., materials with intrinsic quantum confinement) may offer inherent advantages over conventional materials for QISE. The materials challenges for specific types of qubits, along with how emerging nanomaterials may overcome these challenges, are identified. Challenges for and progress toward nanomaterials-based quantum devices are condidered. The overall aim of the review is to help close the gap between the nanotechnology and quantum information communities and inspire research that will lead to next-generation quantum devices for scalable and practical quantum applications.
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Affiliation(s)
- Adam Alfieri
- Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Surendra B Anantharaman
- Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Huiqin Zhang
- Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Deep Jariwala
- Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
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14
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Möller S, Banszerus L, Knothe A, Steiner C, Icking E, Trellenkamp S, Lentz F, Watanabe K, Taniguchi T, Glazman LI, Fal'ko VI, Volk C, Stampfer C. Probing Two-Electron Multiplets in Bilayer Graphene Quantum Dots. PHYSICAL REVIEW LETTERS 2021; 127:256802. [PMID: 35029428 DOI: 10.1103/physrevlett.127.256802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 11/01/2021] [Indexed: 05/21/2023]
Abstract
We report on finite bias spectroscopy measurements of the two-electron spectrum in a gate defined bilayer graphene (BLG) quantum dot for varying magnetic fields. The spin and valley degree of freedom in BLG give rise to multiplets of six orbital symmetric and ten orbital antisymmetric states. We find that orbital symmetric states are lower in energy and separated by ≈ 0.4-0.8 meV from orbital antisymmetric states. The symmetric multiplet exhibits an additional energy splitting of its six states of ≈ 0.15-0.5 meV due to lattice scale interactions. The experimental observations are supported by theoretical calculations, which allow to determine that intervalley scattering and "current-current" interaction constants are of the same magnitude in BLG.
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Affiliation(s)
- S Möller
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - L Banszerus
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - A Knothe
- National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
| | - C Steiner
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
| | - E Icking
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - S Trellenkamp
- Helmholtz Nano Facility, Forschungszentrum Jülich, Jülich 52425, Germany
| | - F Lentz
- Helmholtz Nano Facility, Forschungszentrum Jülich, Jülich 52425, Germany
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - L I Glazman
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - V I Fal'ko
- National Graphene Institute, University of Manchester, Manchester M13 9PL, United Kingdom
- Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
- Henry Royce Institute for Advanced Materials, University of Manchester, Manchester M13 9PL, United Kingdom
| | - C Volk
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, Aachen 52074, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, Jülich 52425, Germany
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