1
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Goteti US, Cybart SA, Dynes RC. Collective neural network behavior in a dynamically driven disordered system of superconducting loops. Proc Natl Acad Sci U S A 2024; 121:e2314995121. [PMID: 38470918 PMCID: PMC10962991 DOI: 10.1073/pnas.2314995121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 02/12/2024] [Indexed: 03/14/2024] Open
Abstract
Collective properties of complex systems composed of many interacting components such as neurons in our brain can be modeled by artificial networks based on disordered systems. We show that a disordered neural network of superconducting loops with Josephson junctions can exhibit computational properties like categorization and associative memory in the time evolution of its state in response to information from external excitations. Superconducting loops can trap multiples of fluxons in many discrete memory configurations defined by the local free energy minima in the configuration space of all possible states. A memory state can be updated by exciting the Josephson junctions to fire or allow the movement of fluxons through the network as the current through them surpasses their critical current thresholds. Simulations performed with a lumped element circuit model of a 4-loop network show that information written through excitations is translated into stable states of trapped flux and their time evolution. Experimental implementation on a high-Tc superconductor YBCO-based 4-loop network shows dynamically stable flux flow in each pathway characterized by the correlations between junction firing statistics. Neural network behavior is observed as energy barriers separating state categories in simulations in response to multiple excitations, and experimentally as junction responses characterizing different flux flow patterns in the network. The state categories that produce these patterns have different temporal stabilities relative to each other and the excitations. This provides strong evidence for time-dependent (short-to-long-term) memories, that are dependent on the geometrical and junction parameters of the loops, as described with a network model.
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Affiliation(s)
- Uday S. Goteti
- Department of Physics, University of California, San Diego, CA92093
| | - Shane A. Cybart
- Department of Electrical and Computer Engineering, University of California, Riverside, CA92521
| | - Robert C. Dynes
- Department of Physics, University of California, San Diego, CA92093
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2
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Skarpeid AJ, Hugdal HG, Salamone T, Amundsen M, Jacobsen SH. Non-constant geometric curvature for tailored spin-orbit coupling and chirality in superconductor-magnet heterostructures. J Phys Condens Matter 2024. [PMID: 38417169 DOI: 10.1088/1361-648x/ad2e23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2024]
Abstract
We show that tailoring the geometric curvature profile of magnets can be used for bespoke design
of an effective non-relativistic spin-orbit coupling, which may be used to control proximity effects if
the magnet is coupled to a superconductor. We consider proximity-coupled one-dimensional magnetic
wires with variable curvatures, specifically three distinct shapes classified as J-, C-, and S-type. We
demonstrate a chirality-dependent spin polarization of the superconducting correlations, and show
the role of curvature in determining the ground state of mixed-chirality junctions. We speculate on
how this may be implemented in novel device design, and include analysis of its usage in a spin-triplet
SQUID.
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Affiliation(s)
- Alv Johan Skarpeid
- Norges teknisk-naturvitenskapelige universitet, Department of Physics, Trondheim, Trøndelag, 7491, NORWAY
| | - Henning G Hugdal
- Department of Physics , Norges teknisk-naturvitenskapelige universitet, 7491 Trondheim, Trondheim, Trøndelag, 7491, NORWAY
| | - Tancredi Salamone
- Department of Physics , Norges teknisk-naturvitenskapelige universitet, 7491 Trondheim, Trondheim, Trøndelag, 7491, NORWAY
| | - Morten Amundsen
- Department of Physics , Norges teknisk-naturvitenskapelige universitet, 7491 Trondheim, Trondheim, Trøndelag, 7491, NORWAY
| | - Sol H Jacobsen
- Department of Physics , Norges teknisk-naturvitenskapelige universitet, 7491 Trondheim, Trondheim, Trøndelag, 7491, NORWAY
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3
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Yan S, Su H, Pan D, Li W, Lyu Z, Chen M, Wu X, Lu L, Zhao J, Wang JY, Xu H. Supercurrent, Multiple Andreev Reflections and Shapiro Steps in InAs Nanosheet Josephson Junctions. Nano Lett 2023. [PMID: 37450769 DOI: 10.1021/acs.nanolett.3c01450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
We report an experimental study of proximity induced superconductivity in planar Josephson junction devices made from free-standing InAs nanosheets. The nanosheets are grown by molecular beam epitaxy, and the Josephson junction devices are fabricated by directly contacting the nanosheets with superconductor Al electrodes. The fabricated devices are explored by low-temperature carrier transport measurements. The measurements show that the devices exhibit a gate-tunable supercurrent, multiple Andreev reflections, and a good quality superconductor-semiconductor interface. The superconducting characteristics of the Josephson junctions are investigated at different magnetic fields and temperatures and are analyzed based on the Bardeen-Cooper-Schrieffer (BCS) theory. The measurements of the ac Josephson effect are also conducted under microwave radiations with different radiation powers and frequencies, and integer Shapiro steps are observed. Our work demonstrates that InAs nanosheet based hybrid devices are desired systems for investigating the forefront of physics, such as two-dimensional topological superconductivity.
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Affiliation(s)
- Shili Yan
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
| | - Haitian Su
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China
- Institute of Condensed Matter and Material Physics, School of Physics, Peking University, Beijing 100871, China
| | - Dong Pan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China
| | - Weijie Li
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Zhaozheng Lyu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Mo Chen
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
| | - Xingjun Wu
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
| | - Li Lu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China
| | - Ji-Yin Wang
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
| | - Hongqi Xu
- Beijing Academy of Quantum Information Sciences, 100193 Beijing, China
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and School of Electronics, Peking University, Beijing 100871, China
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4
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Tarasov M, Lomov A, Chekushkin A, Fominsky M, Zakharov D, Tatarintsev A, Kraevsky S, Shadrin A. Quasiepitaxial Aluminum Film Nanostructure Optimization for Superconducting Quantum Electronic Devices. Nanomaterials (Basel) 2023; 13:2002. [PMID: 37446518 DOI: 10.3390/nano13132002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 06/30/2023] [Accepted: 07/01/2023] [Indexed: 07/15/2023]
Abstract
In this paper, we develop fabrication technology and study aluminum films intended for superconducting quantum nanoelectronics using AFM, SEM, XRD, HRXRR. Two-temperature-step quasiepitaxial growth of Al on (111) Si substrate provides a preferentially (111)-oriented Al polycrystalline film and reduces outgrowth bumps, peak-to-peak roughness from 70 to 10 nm, and texture coefficient from 3.5 to 1.7, while increasing hardness from 5.4 to 16 GPa. Future progress in superconducting current density, stray capacitance, relaxation time, and noise requires a reduction in structural defect density and surface imperfections, which can be achieved by improving film quality using such quasiepitaxial growth techniques.
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Affiliation(s)
- Mikhail Tarasov
- V. Kotelnikov Institute of Radio Engineering and Electronics, Moscow 125009, Russia
| | - Andrey Lomov
- Valiev Institute of Physics and Technology, Moscow 117218, Russia
| | - Artem Chekushkin
- V. Kotelnikov Institute of Radio Engineering and Electronics, Moscow 125009, Russia
| | - Mikhail Fominsky
- V. Kotelnikov Institute of Radio Engineering and Electronics, Moscow 125009, Russia
| | - Denis Zakharov
- Valiev Institute of Physics and Technology, Moscow 117218, Russia
| | | | - Sergey Kraevsky
- V. Orekhovich Institute of Biomedical Chemistry, Moscow 119435, Russia
| | - Anton Shadrin
- Moscow Institute of Physics and Technology, Dolgoprudny 141701, Russia
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5
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Schwarz M, Vethaak TD, Derycke V, Francheteau A, Iniguez B, Kataria S, Kloes A, Lefloch F, Lemme M, Snyder JP, Weber WM, Calvet LE. The Schottky barrier transistor in emerging electronic devices. Nanotechnology 2023; 34:352002. [PMID: 37100049 DOI: 10.1088/1361-6528/acd05f] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 04/25/2023] [Indexed: 06/16/2023]
Abstract
This paper explores how the Schottky barrier (SB) transistor is used in a variety of applications and material systems. A discussion of SB formation, current transport processes, and an overview of modeling are first considered. Three discussions follow, which detail the role of SB transistors in high performance, ubiquitous and cryogenic electronics. For high performance computing, the SB typically needs to be minimized to achieve optimal performance and we explore the methods adopted in carbon nanotube technology and two-dimensional electronics. On the contrary for ubiquitous electronics, the SB can be used advantageously in source-gated transistors and reconfigurable field-effect transistors (FETs) for sensors, neuromorphic hardware and security applications. Similarly, judicious use of an SB can be an asset for applications involving Josephson junction FETs.
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Affiliation(s)
| | - Tom D Vethaak
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Vincent Derycke
- Université Paris-Saclay, CEA, CNRS, NIMBE, LICSEN, Gif-sur-Yvette, F-91191, France
| | | | | | | | | | - Francois Lefloch
- University Grenoble Alps, GINP, CEA-IRIG-PHELIQS, Grenoble, France
| | | | | | - Walter M Weber
- Technische Universität Wien, Institute of Solid State Electronics, Vienna, Austria
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6
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Sameh M, Shukrinov Y, Ellithi AY, El Sherbini T, Nashaat M. Josephson current-assisted reversal of a single-domain nanoscale ferromagnet driven by cosine chirp pulse. J Phys Condens Matter 2023; 35. [PMID: 37207667 DOI: 10.1088/1361-648x/acd73a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Accepted: 05/19/2023] [Indexed: 05/21/2023]
Abstract
We study the microwave-induced magnetization reversal in two systems, the microwave-driven nanomagnet (NM-MW) and the nanomagnet coupled to a Josephson junction under the microwave field (NM-JJ-MW). The frequency of the applied cosine chirp pulse (CCP) changes nonlinearly with time to match the magnetization precession frequency. The coupling between the nanomagnet and Josephson junction reduces the magnetization switching time as well as the optimal amplitude of the microwave field as a result of manipulating the magnetization via Josephson-to-magnetic energy ratioG. The reversal effect in NM-JJ-MW is sufficiently robust against changes in pulse amplitude and duration. In this system, the increase ofGdecreases the possibility of the non-reversing magnetic response as the Gilbert damping increases without further increase in the external microwave field. We also discuss the magnetic response of the nanomagnet driven by the ac field of two Josephson junctions in which the time-dependent frequency is controlled by the voltage across the junctions. Our results provide a controllable scheme of magnetization reversal that might help to realize fast memory devices.
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Affiliation(s)
- Muhammad Sameh
- Department of Physics, Cairo University Faculty of Science, 1 Gamaa Street, Giza, Egypt, Giza, 12613, EGYPT
| | - Yury Shukrinov
- Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 6 Joliot-Curie St, Dubna, Moscow Region, Russia, Dubna, Moskovskaâ, 141980, RUSSIAN FEDERATION
| | - Ali Y Ellithi
- Department of Physics, Cairo University Faculty of Science, 1 Gamaa Street, Giza, Egypt, Giza, 12613, EGYPT
| | - Tharwat El Sherbini
- Department of Physics, Cairo University Faculty of Science, 1 Gamaa Street, Giza, Egypt, Giza, 12613, EGYPT
| | - Majed Nashaat
- Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 6 Joliot-Curie St, Dubna, Moscow Region, Russia, Dubna, Moskovskaâ, 141980, RUSSIAN FEDERATION
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7
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Chiles J, Arnault EG, Chen CC, Larson TFQ, Zhao L, Watanabe K, Taniguchi T, Amet F, Finkelstein G. Nonreciprocal Supercurrents in a Field-Free Graphene Josephson Triode. Nano Lett 2023. [PMID: 37191404 DOI: 10.1021/acs.nanolett.3c01276] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Superconducting diodes are proposed nonreciprocal circuit elements that should exhibit nondissipative transport in one direction while being resistive in the opposite direction. Multiple examples of such devices have emerged in the past couple of years; however, their efficiency is typically limited, and most of them require a magnetic field to function. Here we present a device that achieves efficiencies approaching 100% while operating at zero field. Our samples consist of a network of three graphene Josephson junctions linked by a common superconducting island, to which we refer as a Josephson triode. The three-terminal nature of the device inherently breaks the inversion symmetry, and the control current applied to one of the contacts breaks the time-reversal symmetry. The triode's utility is demonstrated by rectifying a small (nA scale amplitude) applied square wave. We speculate that devices of this type could be realistically employed in the modern quantum circuits.
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Affiliation(s)
- John Chiles
- Department of Physics, Duke University, Durham, North Carolina 27701, United States
| | - Ethan G Arnault
- Department of Physics, Duke University, Durham, North Carolina 27701, United States
| | - Chun-Chia Chen
- Department of Physics, Duke University, Durham, North Carolina 27701, United States
| | - Trevyn F Q Larson
- Department of Physics, Duke University, Durham, North Carolina 27701, United States
| | - Lingfei Zhao
- Department of Physics, Duke University, Durham, North Carolina 27701, United States
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba 305-0044, Japan
| | | | - François Amet
- Department of Physics and Astonomy, Appalachian State University, Boone, North Carolina 28607, United States
| | - Gleb Finkelstein
- Department of Physics, Duke University, Durham, North Carolina 27701, United States
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8
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Vigliotti L, Cavaliere F, Passetti G, Sassetti M, Traverso Ziani N. Reconstruction-Induced φ0 Josephson Effect in Quantum Spin Hall Constrictions. Nanomaterials (Basel) 2023; 13:nano13091497. [PMID: 37177040 PMCID: PMC10180432 DOI: 10.3390/nano13091497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023]
Abstract
The simultaneous breaking of time-reversal and inversion symmetry, in connection to superconductivity, leads to transport properties with disrupting scientific and technological potential. Indeed, the anomalous Josephson effect and the superconducting-diode effect hold promises to enlarge the technological applications of superconductors and nanostructures in general. In this context, the system we theoretically analyze is a Josephson junction (JJ) with coupled reconstructed topological channels as a link; such channels are at the edges of a two-dimensional topological insulator (2DTI). We find a robust φ0 Josephson effect without requiring the presence of external magnetic fields. Our results, which rely on a fully analytical analysis, are substantiated by means of symmetry arguments: Our system breaks both time-reversal symmetry and inversion symmetry. Moreover, the anomalous current increases as a function of temperature. We interpret this surprising temperature dependence by means of simple qualitative arguments based on Fermi's golden rule.
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Affiliation(s)
- Lucia Vigliotti
- Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Fabio Cavaliere
- Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
- CNR-SPIN, Via Dodecaneso 33, 16146 Genova, Italy
| | - Giacomo Passetti
- Institut für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information Technology, 52056 Aachen, Germany
| | - Maura Sassetti
- Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
- CNR-SPIN, Via Dodecaneso 33, 16146 Genova, Italy
| | - Niccolò Traverso Ziani
- Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
- CNR-SPIN, Via Dodecaneso 33, 16146 Genova, Italy
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9
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Lee Y, Martini M, Confalone T, Shokri S, Saggau CN, Wolf D, Gu G, Watanabe K, Taniguchi T, Montemurro D, Vinokur VM, Nielsch K, Poccia N. Encapsulating High-Temperature Superconducting Twisted van der Waals Heterostructures Blocks Detrimental Effects of Disorder. Adv Mater 2023; 35:e2209135. [PMID: 36693810 DOI: 10.1002/adma.202209135] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 01/16/2023] [Indexed: 06/17/2023]
Abstract
High-temperature cuprate superconductors based van der Waals (vdW) heterostructures hold high technological promise. One of the obstacles hindering their progress is the detrimental effect of disorder on the properties of the vdW-devices-based Josephson junctions (JJs). Here, a new method of fabricating twisted vdW heterostructures made of Bi2 Sr2 CuCa2 O8+δ , crucially improving the JJ characteristics and pushing them up to those of the intrinsic JJs in bulk samples, is reported. The method combines cryogenic stacking using a solvent-free stencil mask technique and covering the interface by insulating hexagonal boron nitride crystals. Despite the high-vacuum condition down to 10-6 mbar in the evaporation chamber, the interface appears to be protected from water molecules during the in situ metal deposition only when fully encapsulated. Comparing the current-voltage curves of encapsulated and unencapsulated interfaces, it is revealed that the encapsulated interfaces' characteristics are crucially improved, so that the corresponding JJs demonstrate high critical currents and sharpness of the superconducting transition comparable to those of the intrinsic JJs. Finally, it is shown that the encapsulated heterostructures are more stable over time.
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Affiliation(s)
- Yejin Lee
- Leibniz Institute for Solid State and Materials Science Dresden (IFW Dresden), 01069, Dresden, Germany
- Institute of Applied Physics, Technische Universität Dresden, 01062, Dresden, Germany
| | - Mickey Martini
- Leibniz Institute for Solid State and Materials Science Dresden (IFW Dresden), 01069, Dresden, Germany
- Institute of Applied Physics, Technische Universität Dresden, 01062, Dresden, Germany
| | - Tommaso Confalone
- Leibniz Institute for Solid State and Materials Science Dresden (IFW Dresden), 01069, Dresden, Germany
| | - Sanaz Shokri
- Leibniz Institute for Solid State and Materials Science Dresden (IFW Dresden), 01069, Dresden, Germany
- Institute of Applied Physics, Technische Universität Dresden, 01062, Dresden, Germany
| | - Christian N Saggau
- Leibniz Institute for Solid State and Materials Science Dresden (IFW Dresden), 01069, Dresden, Germany
| | - Daniel Wolf
- Leibniz Institute for Solid State and Materials Science Dresden (IFW Dresden), 01069, Dresden, Germany
| | - Genda Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - 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
| | - Domenico Montemurro
- Department of Physics, University of Naples Federico II, 80125, Naples, Italy
| | | | - Kornelius Nielsch
- Leibniz Institute for Solid State and Materials Science Dresden (IFW Dresden), 01069, Dresden, Germany
- Institute of Applied Physics, Technische Universität Dresden, 01062, Dresden, Germany
| | - Nicola Poccia
- Leibniz Institute for Solid State and Materials Science Dresden (IFW Dresden), 01069, Dresden, Germany
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Vettoliere A, Granata C. Highly Sensitive Tunable Magnetometer Based on Superconducting Quantum Interference Device. Sensors (Basel) 2023; 23:s23073558. [PMID: 37050617 PMCID: PMC10098524 DOI: 10.3390/s23073558] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/20/2023] [Accepted: 03/27/2023] [Indexed: 06/12/2023]
Abstract
In the present article, experimental results regarding fully integrated superconducting quantum interference devices (SQUID), including a circuit to tune and optimize the main sensor device characteristics, are reported. We show the possibility of modifying the critical current of a SQUID magnetometer in liquid helium by means of a suitable heating circuit. This allows us to improve the characteristics of the SQUID sensor and in particular to optimize the voltage-magnetic flux characteristic and the relative transfer factor (responsivity) and consequently to also improve the flux and magnetic field noise. It is also possible to reset the SQUID sensor in case of entrapment of magnetic flux, avoiding taking it out of the helium bath. These results are very useful in view of most SQUID applications such as those requiring large multichannel systems in which it is desirable to optimize and eventually reset the magnetic sensors in a simple and effective way.
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11
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Vigliotti L, Calzona A, Traverso Ziani N, Bergeret FS, Sassetti M, Trauzettel B. Effects of the Spatial Extension of the Edge Channels on the Interference Pattern of a Helical Josephson Junction. Nanomaterials (Basel) 2023; 13:569. [PMID: 36770530 PMCID: PMC9920926 DOI: 10.3390/nano13030569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 01/25/2023] [Accepted: 01/29/2023] [Indexed: 06/18/2023]
Abstract
Josephson junctions (JJs) in the presence of a magnetic field exhibit qualitatively different interference patterns depending on the spatial distribution of the supercurrent through the junction. In JJs based on two-dimensional topological insulators (2DTIs), the electrons/holes forming a Cooper pair (CP) can either propagate along the same edge or be split into the two edges. The former leads to a SQUID-like interference pattern, with the superconducting flux quantum ϕ0 (where ϕ0=h/2e) as a fundamental period. If CPs' splitting is additionally included, the resultant periodicity doubles. Since the edge states are typically considered to be strongly localized, the critical current does not decay as a function of the magnetic field. The present paper goes beyond this approach and inspects a topological JJ in the tunneling regime featuring extended edge states. It is here considered the possibility that the two electrons of a CP propagate and explore the junction independently over length scales comparable to the superconducting coherence length. As a consequence of the spatial extension, a decaying pattern with different possible periods is obtained. In particular, it is shown that, if crossed Andreev reflections (CARs) are dominant and the edge states overlap, the resulting interference pattern features oscillations whose periodicity approaches 2ϕ0.
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Affiliation(s)
- Lucia Vigliotti
- Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Alessio Calzona
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, D-97074 Würzburg, Germany
| | - Niccolò Traverso Ziani
- Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
- CNR-SPIN, Via Dodecaneso 33, 16146 Genova, Italy
| | - F. Sebastian Bergeret
- Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, E-20018 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), E-20018 Donostia-San Sebastián, Spain
| | - Maura Sassetti
- Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
- CNR-SPIN, Via Dodecaneso 33, 16146 Genova, Italy
| | - Björn Trauzettel
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, D-97074 Würzburg, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, D-97074 Würzburg, Germany
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12
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Cattaneo R, Galin MA, Krasnov VM. Observation of collective excitation of surface plasmon resonances in large Josephson junction arrays. Beilstein J Nanotechnol 2022; 13:1578-1588. [PMID: 36636736 PMCID: PMC9811307 DOI: 10.3762/bjnano.13.132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
Josephson junctions can be used as sources of microwave radiation. However, synchronization of many junctions is required for achieving a coherent amplification of the emitted power. In this work we present an experimental study of large arrays containing up to one thousand Nb/Nb x Si1- x /Nb junctions. The arrays exhibit profound cavity mode resonances, corresponding to the formation of standing waves at the electrode/substrate interface. We observe that resonant steps in the current-voltage characteristics appear above some threshold number of junctions, N th ≈ 100, and then progressively enhance in amplitude with further increment of the number of junctions in the resistive oscillating state. We use an external detector to measure the emission of electromagnetic waves. The emission power correlates with the step amplitude. Our results indicate that the emission is facilitated by the cavity modes in the electrodes. The modes are collectively excited by active junctions. In turn, the standing wave imprints its order on the array, facilitating mutual phase-locking of junctions. This provides an indirect coupling mechanism, allowing for the synchronization of junctions, which do not directly interact with each other. Our results demonstrate that electrodes can effectively work as a common external resonator, facilitating long-range phase-locking of large junction arrays with sizes larger than the emitted wavelength.
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Affiliation(s)
- Roger Cattaneo
- Stockholm University, Physics Department, SE-10691 Stockholm, Sweden
| | - Mikhail A Galin
- Institute for Physics of Microstructures RAS, 603950 Nizhny Novgorod, Russia
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Karabassov T, Pashkovskaia VD, Parkhomenko NA, Guravova AV, Kazakova EA, Lvov BG, Golubov AA, Vasenko AS. Density of states in the presence of spin-dependent scattering in SF bilayers: a numerical and analytical approach. Beilstein J Nanotechnol 2022; 13:1418-1431. [PMID: 36540701 PMCID: PMC9732889 DOI: 10.3762/bjnano.13.117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 11/07/2022] [Indexed: 06/17/2023]
Abstract
We present a quantitative study of the density of states (DOS) in SF bilayers (where S is a bulk superconductor and F is a ferromagnetic metal) in the diffusive limit. We solve the quasiclassical Usadel equations in the structure considering the presence of magnetic and spin-orbit scattering. For practical reasons, we propose the analytical solution for the density of states in SF bilayers in the case of a thin ferromagnet and low transparency of the SF interface. This solution is confirmed by numerical calculations using a self-consistent two-step iterative method. The behavior of DOS dependencies on magnetic and spin-orbit scattering times is discussed.
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Affiliation(s)
| | | | | | | | - Elena A Kazakova
- Sechenov First Moscow State Medical University, 119991 Moscow, Russia
| | | | - Alexander A Golubov
- Faculty of Science and Technology and MESA Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands
- Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Andrey S Vasenko
- HSE University, 101000 Moscow, Russia
- I. E. Tamm Department of Theoretical Physics, P. N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
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14
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Turini B, Salimian S, Carrega M, Iorio A, Strambini E, Giazotto F, Zannier V, Sorba L, Heun S. Josephson Diode Effect in High-Mobility InSb Nanoflags. Nano Lett 2022; 22:8502-8508. [PMID: 36285780 PMCID: PMC9650771 DOI: 10.1021/acs.nanolett.2c02899] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 10/21/2022] [Indexed: 05/27/2023]
Abstract
We report nonreciprocal dissipation-less transport in single ballistic InSb nanoflag Josephson junctions. Applying an in-plane magnetic field, we observe an inequality in supercurrent for the two opposite current propagation directions. Thus, these devices can work as Josephson diodes, with dissipation-less current flowing in only one direction. For small fields, the supercurrent asymmetry increases linearly with external field, and then it saturates as the Zeeman energy becomes relevant, before it finally decreases to zero at higher fields. The effect is maximum when the in-plane field is perpendicular to the current vector, which identifies Rashba spin-orbit coupling as the main symmetry-breaking mechanism. While a variation in carrier concentration in these high-quality InSb nanoflags does not significantly influence the supercurrent asymmetry, it is instead strongly suppressed by an increase in temperature. Our experimental findings are consistent with a model for ballistic short junctions and show that the diode effect is intrinsic to this material.
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Affiliation(s)
- Bianca Turini
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127Pisa, Italy
| | - Sedighe Salimian
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127Pisa, Italy
| | | | - Andrea Iorio
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127Pisa, Italy
| | - Elia Strambini
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127Pisa, Italy
| | - Francesco Giazotto
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127Pisa, Italy
| | - Valentina Zannier
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127Pisa, Italy
| | - Lucia Sorba
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127Pisa, Italy
| | - Stefan Heun
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, 56127Pisa, Italy
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15
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Fortin-Deschênes M, Pu R, Zhou YF, Ma C, Cheung P, Watanabe K, Taniguchi T, Zhang F, Du X, Xia F. Uncovering Topological Edge States in Twisted Bilayer Graphene. Nano Lett 2022; 22:6186-6193. [PMID: 35900257 DOI: 10.1021/acs.nanolett.2c01481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Twisted bilayer graphene (t-BLG) has recently been introduced as a rich physical platform displaying flat electronic bands, strongly correlated states, and unconventional superconductivity. Studies have hinted at an unusual Z2 topology of the moiré Dirac bands of t-BLG. However, direct experimental evidence of this moiré band topology and associated edge states is still lacking. Herein, using superconducting quantum interferometry, we reconstructed the spatial supercurrent distribution in t-BLG Josephson junctions and revealed the presence of edge states located in the superlattice band gaps. The absence of edge conduction in high resistance regions just outside the superlattice band gap confirms that the edge transport originates from the filling of electronic states located inside the band gap and further allows us to exclude several other edge conduction mechanisms. These results confirm the unusual moiré band topology of twisted bilayer graphene and will stimulate further research to explore its consequences.
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Affiliation(s)
| | - Rui Pu
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, United States
| | - Yan-Feng Zhou
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 7508, United States
| | - Chao Ma
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, United States
| | - Patrick Cheung
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 7508, United States
| | - 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
| | - Fan Zhang
- Department of Physics, The University of Texas at Dallas, Richardson, Texas 7508, United States
| | - Xu Du
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, United States
| | - Fengnian Xia
- Department of Electrical Engineering, Yale University, New Haven, Connecticut 06511, United States
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16
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Olaya D, Biesecker J, Castellanos-Beltran M, Sirois A, Howe L, Dresselhaus P, Benz S, Hopkins P. Nb/ a-Si/Nb-junction Josephson arbitrary waveform synthesizers for quantum information. IEEE Trans Appl Supercond 2022; 33:10.1109/tasc.2023.3249141. [PMID: 37720264 PMCID: PMC10502609 DOI: 10.1109/tasc.2023.3249141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
We demonstrate Josephson arbitrary waveform synthesizers (JAWS) with increased operating temperature range for temperatures below 4 K. These JAWS synthesizers were fabricated with externally-shunted Nb/a-Si/Nb junctions whose critical current exhibits improved temperature stability compared to the self-shunted Nb/Nb0.15Si0.85/Nb junctions typically used. Vertical stud resistors made of 230 nm of PdAu were developed to provide the milliohm shunt resistance required for junction overdamping while maintaining a small footprint suitable for high-density series arrays embedded in a coplanar waveguide. We evaluated the performance of these resistors from 3.8 K down to 20 mK. We designed, fabricated and tested a JAWS circuit with 4650 externally shunted Nb/a-Si/Nb JJs with a critical current density (J c ) of 0.12 mA ∕ μ m 2 and critical current (I c ) of 3 mA. This circuit was designed to be mounted to the 3 K stage of a dilution refrigerator and used to control and calibrate a qubit mounted at the 10 mK stage. To increase the circuit density of the JAWS circuits we made arrays of two-junction vertical stacks. Current-voltage (I - V ) curves of this JAWS circuit with stacked junctions under microwave excitation show Shapiro steps with quantum-locking ranges similar to those of JAWS circuits used for qubit control.
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Affiliation(s)
- David Olaya
- Department of Physics at the University of Colorado, Boulder, CO; RF Technology Division of the National Institute of Standards and Technology, Boulder, CO, USA
| | - John Biesecker
- RF Technology Division of the National Institute of Standards and Technology, Boulder, CO, USA
| | | | - Adam Sirois
- RF Technology Division of the National Institute of Standards and Technology, Boulder, CO, USA
| | - Logan Howe
- Department of Physics at the University of Colorado, Boulder, CO; RF Technology Division of the National Institute of Standards and Technology, Boulder, CO, USA
| | - Paul Dresselhaus
- RF Technology Division of the National Institute of Standards and Technology, Boulder, CO, USA
| | - Samuel Benz
- RF Technology Division of the National Institute of Standards and Technology, Boulder, CO, USA
| | - Peter Hopkins
- RF Technology Division of the National Institute of Standards and Technology, Boulder, CO, USA
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17
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Stolyarov VS, Ruzhitskiy V, Hovhannisyan RA, Grebenchuk S, Shishkin AG, Skryabina OV, Golovchanskiy IA, Golubov AA, Klenov NV, Soloviev II, Kupriyanov MY, Andriyash A, Roditchev D. Revealing Josephson Vortex Dynamics in Proximity Junctions below Critical Current. Nano Lett 2022; 22:5715-5722. [PMID: 35820103 DOI: 10.1021/acs.nanolett.2c00647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Made of a thin non-superconducting metal (N) sandwiched by two superconductors (S), SNS Josephson junctions enable novel quantum functionalities by mixing up the intrinsic electronic properties of N with the superconducting correlations induced from S by proximity. Electronic properties of these devices are governed by Andreev quasiparticles (Andreev, A. Sov. Phys. JETP 1965, 20, 1490) which are absent in conventional SIS junctions whose insulating barrier (I) between the two S electrodes owns no electronic states. Here we focus on the Josephson vortex (JV) motion inside Nb-Cu-Nb proximity junctions subject to electric currents and magnetic fields. The results of local (magnetic force microscopy) and global (transport) experiments provided simultaneously are compared with our numerical model, revealing the existence of several distinct dynamic regimes of the JV motion. One of them, identified as a fast hysteretic entry/escape below the critical value of Josephson current, is analyzed and suggested for low-dissipative logic and memory elements.
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Affiliation(s)
- Vasily S Stolyarov
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Vsevolod Ruzhitskiy
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Razmik A Hovhannisyan
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Sergey Grebenchuk
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Andrey G Shishkin
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Olga V Skryabina
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Institute of Solid State Physics RAS, 142432 Chernogolovka, Russia
| | - Igor A Golovchanskiy
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Alexander A Golubov
- Faculty of Science and Technology, MESA+ Institute of Nanotechnology, 7500 AE Enschede, The Netherlands
| | - Nikolay V Klenov
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Igor I Soloviev
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Mikhail Yu Kupriyanov
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | | | - Dimitri Roditchev
- LPEM, ESPCI Paris, PSL Research University, CNRS, 75005 Paris, France
- Sorbonne Universite, CNRS, LPEM, 75005 Paris, France
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18
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Schmitt TW, Connolly MR, Schleenvoigt M, Liu C, Kennedy O, Chávez-Garcia JM, Jalil AR, Bennemann B, Trellenkamp S, Lentz F, Neumann E, Lindström T, de Graaf SE, Berenschot E, Tas N, Mussler G, Petersson KD, Grützmacher D, Schüffelgen P. Integration of Topological Insulator Josephson Junctions in Superconducting Qubit Circuits. Nano Lett 2022; 22:2595-2602. [PMID: 35235321 DOI: 10.1021/acs.nanolett.1c04055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The integration of semiconductor Josephson junctions (JJs) in superconducting quantum circuits provides a versatile platform for hybrid qubits and offers a powerful way to probe exotic quasiparticle excitations. Recent proposals for using circuit quantum electrodynamics (cQED) to detect topological superconductivity motivate the integration of novel topological materials in such circuits. Here, we report on the realization of superconducting transmon qubits implemented with (Bi0.06Sb0.94)2Te3 topological insulator (TI) JJs using ultrahigh vacuum fabrication techniques. Microwave losses on our substrates, which host monolithically integrated hardmasks used for the selective area growth of TI nanostructures, imply microsecond limits to relaxation times and, thus, their compatibility with strong-coupling cQED. We use the cavity-qubit interaction to show that the Josephson energy of TI-based transmons scales with their JJ dimensions and demonstrate qubit control as well as temporal quantum coherence. Our results pave the way for advanced investigations of topological materials in both novel Josephson and topological qubits.
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Affiliation(s)
- Tobias W Schmitt
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
- JARA-Institute for Green IT, Peter Grünberg Institute 10, Forschungszentrum Jülich and RWTH Aachen University, 52062 Aachen, Germany
| | - Malcolm R Connolly
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1H 0AH, United Kingdom
| | - Michael Schleenvoigt
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
| | - Chenlu Liu
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
| | - Oscar Kennedy
- London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1H 0AH, United Kingdom
| | - José M Chávez-Garcia
- Microsoft Quantum Lab Copenhagen and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Abdur R Jalil
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
| | - Benjamin Bennemann
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
| | - Stefan Trellenkamp
- Helmholtz Nano Facility, Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Florian Lentz
- Helmholtz Nano Facility, Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Elmar Neumann
- Helmholtz Nano Facility, Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Tobias Lindström
- National Physical Laboratory, Teddington TW11 0LW, United Kingdom
| | | | - Erwin Berenschot
- MESA+ Institute, University of Twente, 7500AE Enschede, The Netherlands
| | - Niels Tas
- MESA+ Institute, University of Twente, 7500AE Enschede, The Netherlands
| | - Gregor Mussler
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
| | - Karl D Petersson
- Microsoft Quantum Lab Copenhagen and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Detlev Grützmacher
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
- JARA-Institute for Green IT, Peter Grünberg Institute 10, Forschungszentrum Jülich and RWTH Aachen University, 52062 Aachen, Germany
| | - Peter Schüffelgen
- Institute for Semiconductor Nanoelectronics, Peter Grünberg Institute 9, Forschungszentrum Jülich & Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich and RWTH Aachen University, 52428 Jülich, Germany
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19
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Lapham P, Georgiev VP. Computational study of oxide stoichiometry and variability in the Al/AlOx/Al tunnel junction. Nanotechnology 2022; 33:265201. [PMID: 35303731 DOI: 10.1088/1361-6528/ac5f2e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/18/2022] [Indexed: 06/14/2023]
Abstract
Aluminium tunnel junctions are key components of a wide variety of electronic devices. These superconducting tunnel junctions, known as Josephson Junctions (JJ's) are one of the main components of superconducting qubits, a favourite qubit technology in the race for working quantum computers. In this simulation study our JJ configurations are modelled as two aluminium electrodes which are separated by a thin layer of amorphous aluminium oxide. There is limited understanding of how the structure of the amorphous oxide barrier affects the performance and shortcomings of JJ systems. In this paper we present a computational study which combines molecular dynamics, atomistic semi-empirical methods (Density Functional Tight Binding) and non-equilibrium Green's function to study the electronic structure and current flow of these junction devices. Our results suggest that the atomic nature of the amorphous barrier linked to aluminum-oxygen coordination sensitively affects the current-voltage (IV) characteristics, resistance and critical current. Oxide stoichiometry is an important parameter that can lead to variation in resistance and critical currents of several orders of magnitude. The simulations further illustrate the variability that arises due to small differences in atomic structure across amorphous barriers with the same stoichiometry, density and barrier length. Our results also confirm that the charge transport through the barrier is dominated by metallic conduction pathways.
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Affiliation(s)
- Paul Lapham
- Device Modelling Group, James Watt School of Engineering, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Vihar P Georgiev
- Device Modelling Group, James Watt School of Engineering, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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20
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Telesio F, Carrega M, Cappelli G, Iorio A, Crippa A, Strambini E, Giazotto F, Serrano-Ruiz M, Peruzzini M, Heun S. Evidence of Josephson Coupling in a Few-Layer Black Phosphorus Planar Josephson Junction. ACS Nano 2022; 16:3538-3545. [PMID: 35099941 PMCID: PMC8945388 DOI: 10.1021/acsnano.1c09315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Setting up strong Josephson coupling in van der Waals materials in close proximity to superconductors offers several opportunities both to inspect fundamental physics and to develop cryogenic quantum technologies. Here we show evidence of Josephson coupling in a planar few-layer black phosphorus junction. The planar geometry allows us to probe the junction behavior by means of external gates, at different carrier concentrations. Clear signatures of Josephson coupling are demonstrated by measuring supercurrent flow through the junction at milli-Kelvin temperatures. Manifestation of a Fraunhofer pattern with a transverse magnetic field is also reported, confirming the Josephson coupling. These findings represent evidence of proximity Josephson coupling in a planar junction based on a van der Waals material beyond graphene and will expedite further studies, exploiting the peculiar properties of exfoliated black phosphorus thin flakes.
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Affiliation(s)
- Francesca Telesio
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | | | - Giulio Cappelli
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Andrea Iorio
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Alessandro Crippa
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Elia Strambini
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Francesco Giazotto
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | | | | | - Stefan Heun
- NEST,
Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
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21
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Bukatova D, Zolotaryuk Y. Flat and almost flat bands in the quasi-one-dimensional Josephson junction array. J Phys Condens Matter 2022; 34:175402. [PMID: 35086081 DOI: 10.1088/1361-648x/ac4f7f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
The dispersion law for the linear waves in the quasi-one-dimensional array of inductively coupled Josephson junctions (JJs) is derived. The array has a multiladder structure that consists of the finite number of rows (N⩾ 2) inYdirection and is infinite inXdirection. The spectrum of the linear waves (Josephson plasmons) consists of 2N- 1 branches. Among these branches there is anN-fold completely flat degenerate one that coincides with the Josephson plasma frequency. The remainingN- 1 branches have a standard Josephson plasmon dispersion law typical for 1D JJ arrays. Application of the uniform dc bias on the top of each vertical column of junctions lifts the degeneracy and only one flat branch remains unchanged. The rest of the previously flat branches become weakly dispersive. The parameter range where the flatness of these branches is maximal has been discussed.
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Affiliation(s)
- Daryna Bukatova
- Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, Kyiv 03143, Ukraine
| | - Yaroslav Zolotaryuk
- Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, Kyiv 03143, Ukraine
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22
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Krasnov MM, Novikova ND, Cattaneo R, Kalenyuk AA, Krasnov VM. Design aspects of Bi 2Sr 2CaCu 2O 8+δ THz sources: optimization of thermal and radiative properties. Beilstein J Nanotechnol 2021; 12:1392-1403. [PMID: 35004123 PMCID: PMC8712971 DOI: 10.3762/bjnano.12.103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 12/02/2021] [Indexed: 06/14/2023]
Abstract
Impedance matching and heat management are important factors influencing the performance of terahertz sources. In this work we analyze thermal and radiative properties of such devices based on mesa structures of a layered high-temperature superconductor Bi2Sr2CaCu2O8+δ. Two types of devices are considered containing either a conventional large single crystal or a whisker. We perform numerical simulations for various geometrical configurations and parameters and make a comparison with experimental data for the two types of devices. It is demonstrated that the structure and the geometry of both the superconductor and the electrodes play important roles. In crystal-based devices an overlap between the crystal and the electrode leads to appearance of a large parasitic capacitance, which shunts terahertz emission and prevents impedance matching with open space. The overlap is avoided in whisker-based devices. Furthermore, the whisker and the electrodes form a turnstile (crossed-dipole) antenna facilitating good impedance matching. This leads to more than an order of magnitude enhancement of the radiation power efficiency in whisker-based, compared to crystal-based, devices. These results are in good agreement with presented experimental data.
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Affiliation(s)
- Mikhail M Krasnov
- Keldysh Institute of Applied Mathematics of RAS, Moscow, Russia
- Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Natalia D Novikova
- Keldysh Institute of Applied Mathematics of RAS, Moscow, Russia
- Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Roger Cattaneo
- Department of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | - Alexey A Kalenyuk
- Department of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
- Institute of Metal Physics of National Academy of Sciences of Ukraine, 03142 Kyiv, Ukraine
- Kyiv Academic University, 03142 Kyiv, Ukraine
| | - Vladimir M Krasnov
- Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Department of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
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23
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Moehle CM, Ke CT, Wang Q, Thomas C, Xiao D, Karwal S, Lodari M, van de Kerkhof V, Termaat R, Gardner GC, Scappucci G, Manfra MJ, Goswami S. InSbAs Two-Dimensional Electron Gases as a Platform for Topological Superconductivity. Nano Lett 2021; 21:9990-9996. [PMID: 34793173 DOI: 10.1021/acs.nanolett.1c03520] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Topological superconductivity can be engineered in semiconductors with strong spin-orbit interaction coupled to a superconductor. Experimental advances in this field have often been triggered by the development of new hybrid material systems. Among these, two-dimensional electron gases (2DEGs) are of particular interest due to their inherent design flexibility and scalability. Here, we discuss results on a 2D platform based on a ternary 2DEG (InSbAs) coupled to in situ grown aluminum. The spin-orbit coupling in these 2DEGs can be tuned with the As concentration, reaching values up to 400 meV Å, thus exceeding typical values measured in its binary constituents. In addition to a large Landé g-factor of ∼55 (comparable to that of InSb), we show that the clean superconductor-semiconductor interface leads to a hard induced superconducting gap. Using this new platform, we demonstrate the basic operation of phase-controllable Josephson junctions, superconducting islands, and quasi-1D systems, prototypical device geometries used to study Majorana zero modes.
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Affiliation(s)
- Christian M Moehle
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Chung Ting Ke
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Qingzhen Wang
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Candice Thomas
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Di Xiao
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Saurabh Karwal
- QuTech and Netherlands Organization for Applied Scientific Research (TNO), 2628 CK Delft, The Netherlands
| | - Mario Lodari
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Vincent van de Kerkhof
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Ruben Termaat
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Geoffrey C Gardner
- Microsoft Quantum Purdue, Purdue University, West Lafayette, Indiana 47907, United States
| | - Giordano Scappucci
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Michael J Manfra
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
- Microsoft Quantum Purdue, Purdue University, West Lafayette, Indiana 47907, United States
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Srijit Goswami
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
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24
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Tian J, Jauregui LA, Wilen CD, Rigosi AF, Newell DB, McDermott R, Chen YP. A Josephson junction with h-BN tunnel barrier: observation of low critical current noise. J Phys Condens Matter 2021; 33:495301. [PMID: 34521077 PMCID: PMC10390952 DOI: 10.1088/1361-648x/ac268f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
Decoherence in quantum bits (qubits) is a major challenge for realizing scalable quantum computing. One of the primary causes of decoherence in qubits and quantum circuits based on superconducting Josephson junctions is the critical current fluctuation. Many efforts have been devoted to suppressing the critical current fluctuation in Josephson junctions. Nonetheless, the efforts have been hindered by the defect-induced trapping states in oxide-based tunnel barriers and the interfaces with superconductors in the traditional Josephson junctions. Motivated by this, along with the recent demonstration of 2D insulatorh-BN with exceptional crystallinity and low defect density, we fabricated a vertical NbSe2/h-BN/Nb Josephson junction consisting of a bottom NbSe2superconductor thin layer and a top Nb superconductor spaced by an atomically thinh-BN layer. We further characterized the superconducting current and voltage (I-V) relationships and Fraunhofer pattern of the NbSe2/h-BN/Nb junction. Notably, we demonstrated the critical current noise (1/fnoise power) in theh-BN-based Josephson device is at least a factor of four lower than that of the previously studied aluminum oxide-based Josephson junctions. Our work offers a strong promise ofh-BN as a novel tunnel barrier for high-quality Josephson junctions and qubit applications.
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Affiliation(s)
- Jifa Tian
- Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, United States of America
- Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, United States of America
- National Institute of Standards and Technology, Gaithersburg, MD 20899, United States of America
| | - Luis A Jauregui
- Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, United States of America
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, United States of America
| | - C D Wilen
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, United States of America
| | - Albert F Rigosi
- National Institute of Standards and Technology, Gaithersburg, MD 20899, United States of America
| | - David B Newell
- National Institute of Standards and Technology, Gaithersburg, MD 20899, United States of America
| | - R McDermott
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, United States of America
| | - Yong P Chen
- Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, United States of America
- Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, IN 47907, United States of America
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, United States of America
- Institute of Physics and Astronomy and Villum Centers for Dirac Materials and for Hybrid Quantum Materials, Aarhus University, 8000 Aarhus-C, Denmark
- WPI-AIMR International Research Center for Materials Sciences, Tohoku University, Sendai 980-8577, Japan
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25
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Golod T, Hovhannisyan RA, Kapran OM, Dremov VV, Stolyarov VS, Krasnov VM. Reconfigurable Josephson Phase Shifter. Nano Lett 2021; 21:5240-5246. [PMID: 34114467 PMCID: PMC8289326 DOI: 10.1021/acs.nanolett.1c01366] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/08/2021] [Indexed: 06/01/2023]
Abstract
Phase shifter is one of the key elements of quantum electronics. In order to facilitate operation and avoid decoherence, it has to be reconfigurable, persistent, and nondissipative. In this work, we demonstrate prototypes of such devices in which a Josephson phase shift is generated by coreless superconducting vortices. The smallness of the vortex allows a broad-range tunability by nanoscale manipulation of vortices in a micron-size array of vortex traps. We show that a phase shift in a device containing just a few vortex traps can be reconfigured between a large number of quantized states in a broad [-3π, +3π] range.
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Affiliation(s)
- Taras Golod
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | - Razmik A. Hovhannisyan
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
- Moscow
Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Olena M. Kapran
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | | | | | - Vladimir M. Krasnov
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
- Moscow
Institute of Physics and Technology, 141700 Dolgoprudny, Russia
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26
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Kinev NV, Rudakov KI, Filippenko LV, Baryshev AM, Koshelets VP. Terahertz Spectroscopy of Gas Absorption Using the Superconducting Flux-Flow Oscillator as an Active Source and the Superconducting Integrated Receiver. Sensors (Basel) 2020; 20:E7267. [PMID: 33352914 DOI: 10.3390/s20247267] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/12/2020] [Accepted: 12/14/2020] [Indexed: 11/17/2022]
Abstract
We report on the first implementation of a terahertz (THz) source based on a Josephson flux-flow oscillator (FFO) that radiates to open space. The excellent performance of this source and its maturity for practical applications has been demonstrated by the spectroscopy of gas absorption. To study the radiated power, we used a bolometric detection method and additionally calibrated the power by means of pumping the superconductor-insulator-superconductor (SIS) junction, integrated on a single chip with the FFO. For calibration, we developed a program using the SIS-detected power calculations in accordance with the Tien and Gordon model. The power emitted to open space is estimated to be from fractions of µW to several µW in the wide region from 0.25 THz up to 0.75 THz for different designs, with a maximum power of 3.3 µW at 0.34 THz. Next, we used a gas cell and a heterodyne superconducting integrated receiver to trace the absorption lines of water and ammonia with a spectral resolution better than 100 kHz. Our experiment for gas absorption is the first demonstration of the applicability of the FFO as an external active source for different tasks, such as THz spectroscopy, near-field THz imaging and microscopy.
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27
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Indolese DI, Karnatak P, Kononov A, Delagrange R, Haller R, Wang L, Makk P, Watanabe K, Taniguchi T, Schönenberger C. Compact SQUID Realized in a Double-Layer Graphene Heterostructure. Nano Lett 2020; 20:7129-7135. [PMID: 32872789 DOI: 10.1021/acs.nanolett.0c02412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
2D systems that host 1D helical states are advantageous from the perspective of scalable topological quantum computation when coupled to a superconductor. Graphene is particularly promising for its high electronic quality, its versatility in van der Waals heterostructures, and its electron- and hole-like degenerate 0th Landau level. Here we study a compact double-layer graphene SQUID (superconducting quantum interference device), where the superconducting loop is reduced to the superconducting contacts connecting two parallel graphene Josephson junctions. Despite the small size of the SQUID, it is fully tunable by the independent gate control of the chemical potentials in both layers. Furthermore, both Josephson junctions show a skewed current-phase relationship, indicating the presence of superconducting modes with high transparency. In the quantum Hall regime, we measure a well-defined conductance plateau of 2e2/h indicative of counter-propagating edge channels in the two layers.
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Affiliation(s)
- David I Indolese
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Paritosh Karnatak
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Artem Kononov
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Raphaëlle Delagrange
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Roy Haller
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Lujun Wang
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
- Swiss Nanoscience institute, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Péter Makk
- Department of Physics, Budapest University of Technology and Economics and Nanoelectronics Momentum Research Group of the Hungarian Academy of Sciences, Budafoki ut 8, 1111 Budapest, Hungary
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Christian Schönenberger
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
- Swiss Nanoscience institute, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
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28
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Ahmadkhani S, Hosseini MV. Superconducting proximity effect in flat band systems. J Phys Condens Matter 2020; 32:315504. [PMID: 32224514 DOI: 10.1088/1361-648x/ab849a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/30/2020] [Indexed: 06/10/2023]
Abstract
We study theoretically proximity-induced superconductivity and its inverse effect in dice lattice flat band model by considering Josephson junction with an s-wave pairing in the superconducting leads. Using self-consistent tight-binding Bogoliubov-de Gennes method, we show that there is a critical value for chemical potential of the superconductors depending on paring interaction strength over which for undoped normal region the proximity effect is enhanced. Whereas if the supserconductor chemical potential is less than the critical one the proximity effect decreases regardless of normal region doping and in the meanwhile, the pairing amplitude of superconducting region increases significantly. Furthermore, we unveil that the supercurrent passing through the junction is large (vanishingly small) when the superconductor chemical potential is smaller (larger) than the critical value which increases as a function of normal region chemical potential.
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Affiliation(s)
- Somayeh Ahmadkhani
- Department of Physics, Faculty of Science, University of Zanjan, Zanjan 45371-38791, Iran
| | - Mir Vahid Hosseini
- Department of Physics, Faculty of Science, University of Zanjan, Zanjan 45371-38791, Iran
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29
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Stehno MP, Ngabonziza P, Myoren H, Brinkman A. Josephson Effect and Charge Distribution in Thin Bi 2 Te 3 Topological Insulators. Adv Mater 2020; 32:e1908351. [PMID: 32091158 DOI: 10.1002/adma.201908351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/24/2020] [Indexed: 06/10/2023]
Abstract
Thin layers of topological insulator materials are quasi-2D systems featuring a complex interplay between quantum confinement and topological band structure. To understand the role of the spatial distribution of carriers in electrical transport, the Josephson effect, magnetotransport, and weak anti-localization are studied in bottom-gated thin Bi2 Te3 topological insulator films. The experimental carrier densities are compared to a model based on the solutions of the self-consistent Schrödinger-Poisson equations and they are in excellent agreement. The modeling allows for a quantitative interpretation of the weak antilocalization correction to the conduction and of the critical current of Josephson junctions with weak links made from such films without any ad hoc assumptions.
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Affiliation(s)
- Martin P Stehno
- Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE, Enschede, The Netherlands
- Physikalisches Institut EP3, University of Würzburg, Am Hubland, 97070, Würzburg, Germany
| | - Prosper Ngabonziza
- Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE, Enschede, The Netherlands
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
- Department of Physics, University of Johannesburg, P.O. Box 524 Auckland Park, 2006, Johannesburg, South Africa
| | - Hiroaki Myoren
- Graduate school of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, 338-8570, Japan
| | - Alexander Brinkman
- Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, 7500 AE, Enschede, The Netherlands
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30
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Karabassov T, Guravova AV, Kuzin AY, Kazakova EA, Kawabata S, Lvov BG, Vasenko AS. Anomalous current-voltage characteristics of SFIFS Josephson junctions with weak ferromagnetic interlayers. Beilstein J Nanotechnol 2020; 11:252-262. [PMID: 32082964 PMCID: PMC7006479 DOI: 10.3762/bjnano.11.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/14/2020] [Indexed: 06/10/2023]
Abstract
We present a quantitative study of the current-voltage characteristics (CVC) of SFIFS Josephson junctions (S = bulk superconductor, F = metallic ferromagnet, I = insulating barrier) with weak ferromagnetic interlayers in the diffusive limit. The problem is solved in the framework of the nonlinear Usadel equations. We consider the case of a strong tunnel barrier such that the left SF and the right FS bilayers are decoupled. We calculate the density of states (DOS) in SF bilayers using a self-consistent numerical method. Then we obtain the CVC of corresponding SFIFS junctions, and discuss their properties for different set of parameters including the thicknesses of ferromagnetic layers, the exchange field, and the magnetic scattering time. We observe an anomalous nonmonotonic CVC in case of weak ferromagnetic interlayers, which we attribute to DOS energy dependencies in the case of small exchange fields in the F layers.
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Affiliation(s)
- Tairzhan Karabassov
- National Research University Higher School of Economics, 101000 Moscow, Russia
| | | | - Aleksei Yu Kuzin
- Skolkovo Institute of Science and Technology, 121205 Moscow, Russia
- Department of Physics, Moscow State Pedagogical University, 119992 Moscow, Russia
| | - Elena A Kazakova
- Sechenov First Moscow State Medical University, 119991 Moscow, Russia
| | - Shiro Kawabata
- National Institute of Advanced Industrial Science and Technology,1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan
| | - Boris G Lvov
- National Research University Higher School of Economics, 101000 Moscow, Russia
| | - Andrey S Vasenko
- National Research University Higher School of Economics, 101000 Moscow, Russia
- I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
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31
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Lee KH, Chakram S, Kim SE, Mujid F, Ray A, Gao H, Park C, Zhong Y, Muller DA, Schuster DI, Park J. Two-Dimensional Material Tunnel Barrier for Josephson Junctions and Superconducting Qubits. Nano Lett 2019; 19:8287-8293. [PMID: 31661615 DOI: 10.1021/acs.nanolett.9b03886] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Quantum computing based on superconducting qubits requires the understanding and control of the materials, device architecture, and operation. However, the materials for the central circuit element, the Josephson junction, have mostly been focused on using the AlOx tunnel barrier. Here, we demonstrate Josephson junctions and superconducting qubits employing two-dimensional materials as the tunnel barrier. We batch-fabricate and design the critical Josephson current of these devices via layer-by-layer stacking N layers of MoS2 on the large scale. Based on such junctions, MoS2 transmon qubits are engineered and characterized in a bulk superconducting microwave resonator for the first time. Our work allows Josephson junctions to access the diverse material properties of two-dimensional materials that include a wide range of electrical and magnetic properties, which can be used to study the effects of different material properties in superconducting qubits and to engineer novel quantum circuit elements in the future.
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Affiliation(s)
- Kan-Heng Lee
- School of Applied and Engineering Physics , Cornell University , Ithaca , New York 14853 , United States
- Pritzker School of Molecular Engineering , University of Chicago , Chicago , Illinois 60637 , United States
| | - Srivatsan Chakram
- James Franck Institute , University of Chicago , Chicago , Illinois 60637 , United States
- Department of Physics , University of Chicago , Chicago , Illinois 60637 , United States
| | - Shi En Kim
- Pritzker School of Molecular Engineering , University of Chicago , Chicago , Illinois 60637 , United States
| | - Fauzia Mujid
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Ariana Ray
- School of Applied and Engineering Physics , Cornell University , Ithaca , New York 14853 , United States
| | - Hui Gao
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Chibeom Park
- James Franck Institute , University of Chicago , Chicago , Illinois 60637 , United States
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Yu Zhong
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - David A Muller
- School of Applied and Engineering Physics , Cornell University , Ithaca , New York 14853 , United States
| | - David I Schuster
- Pritzker School of Molecular Engineering , University of Chicago , Chicago , Illinois 60637 , United States
- James Franck Institute , University of Chicago , Chicago , Illinois 60637 , United States
- Department of Physics , University of Chicago , Chicago , Illinois 60637 , United States
| | - Jiwoong Park
- Pritzker School of Molecular Engineering , University of Chicago , Chicago , Illinois 60637 , United States
- James Franck Institute , University of Chicago , Chicago , Illinois 60637 , United States
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
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32
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Birge NO. Spin-triplet supercurrents in Josephson junctions containing strong ferromagnetic materials. Philos Trans A Math Phys Eng Sci 2018; 376:20150150. [PMID: 29941625 PMCID: PMC6030151 DOI: 10.1098/rsta.2015.0150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/28/2015] [Indexed: 06/08/2023]
Abstract
The proximity effect between a superconducting material and a non-superconducting normal metal can extend over distances of the order of micrometres at sufficiently low temperatures. If the normal metal is replaced by a ferromagnetic material, the spatial extent of the proximity effect drops precipitously due to the exchange splitting between the majority and minority spin bands in the ferromagnet. In 2001, several theorists predicted that spin-triplet pair correlations could be induced in proximity systems involving multiple ferromagnetic materials (or multiple domains in one material) with non-collinear magnetizations. Such spin-triplet pair correlations should extend deep into the ferromagnet, producing a long-range proximity effect. In this paper, we review our experimental work in this area, which has focused primarily on Josephson junctions containing strong ferromagnetic materials. We show that Josephson junctions containing particular combinations of strong ferromagnetic materials can carry spin-triplet supercurrent over distances of at least several tens of nanometres, whereas spin-singlet supercurrent in similar samples decays over a length scale of about 1 nm. We also mention important work by other groups; however, this article is not intended to be a review of the whole field.This article is part of the theme issue 'Andreev bound states'.
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Affiliation(s)
- Norman O Birge
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
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33
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Marra P, Braggio A, Citro R. A zero-dimensional topologically nontrivial state in a superconducting quantum dot. Beilstein J Nanotechnol 2018; 9:1705-1714. [PMID: 29977704 PMCID: PMC6009423 DOI: 10.3762/bjnano.9.162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/09/2018] [Indexed: 06/08/2023]
Abstract
The classification of topological states of matter in terms of unitary symmetries and dimensionality predicts the existence of nontrivial topological states even in zero-dimensional systems, i.e., systems with a discrete energy spectrum. Here, we show that a quantum dot coupled with two superconducting leads can realize a nontrivial zero-dimensional topological superconductor with broken time-reversal symmetry, which corresponds to the finite size limit of the one-dimensional topological superconductor. Topological phase transitions corresponds to a change of the fermion parity, and to the presence of zero-energy modes and discontinuities in the current-phase relation at zero temperature. These fermion parity transitions therefore can be revealed by the current discontinuities or by a measure of the critical current at low temperatures.
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Affiliation(s)
- Pasquale Marra
- RIKEN Center for Emergent Matter Science, Wakoshi, Saitama 351-0198, Japan
| | - Alessandro Braggio
- NEST, Istituto Nanoscienze CNR and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Roberta Citro
- Dipartimento di Fisica “E. R. Caianiello”, Università di Salerno and CNR-SPIN, 84084 Fisciano (Salerno), Italy
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34
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Delfanazari K, Puddy RK, Ma P, Yi T, Cao M, Gul Y, Farrer I, Ritchie DA, Joyce HJ, Kelly MJ, Smith CG. On-Chip Andreev Devices: Hard Superconducting Gap and Quantum Transport in Ballistic Nb-In 0.75 Ga 0.25 As-Quantum-Well-Nb Josephson Junctions. Adv Mater 2017; 29:1701836. [PMID: 28804969 DOI: 10.1002/adma.201701836] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 05/24/2017] [Indexed: 06/07/2023]
Abstract
A superconducting hard gap in hybrid superconductor-semiconductor devices has been found to be necessary to access topological superconductivity that hosts Majorana modes (non-Abelian excitation). This requires the formation of homogeneous and barrier-free interfaces between the superconductor and semiconductor. Here, a new platform is reported for topological superconductivity based on hybrid Nb-In0.75 Ga0.25 As-quantum-well-Nb that results in hard superconducting gap detection in symmetric, planar, and ballistic Josephson junctions. It is shown that with careful etching, sputtered Nb films can make high-quality and transparent contacts to the In0.75 Ga0.25 As quantum well, and the differential resistance and critical current measurements of these devices are discussed as a function of temperature and magnetic field. It is demonstrated that proximity-induced superconductivity in the In0.75 Ga0.25 As-quantum-well 2D electron gas results in the detection of a hard gap in four out of seven junctions on a chip with critical current values of up to 0.2 µA and transmission probabilities of >0.96. The results, together with the large g-factor and Rashba spin-orbit coupling in In0.75 Ga0.25 As quantum wells, which indeed can be tuned by the indium composition, suggest that the Nb-In0.75 Ga0.25 As-Nb system can be an excellent candidate to achieve topological phase and to realize hybrid topological superconducting devices.
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Affiliation(s)
- Kaveh Delfanazari
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
- Centre for Advanced Photonics and Electronics, Electrical Engineering Division, University of Cambridge, Cambridge, CB3 0FA, UK
| | - Reuben K Puddy
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Pengcheng Ma
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Teng Yi
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Moda Cao
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Yilmaz Gul
- Department of Electronic and Electrical Engineering, University College London, London, WC1E 7JE, UK
| | - Ian Farrer
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
- Department of Electronic and Electrical Engineering, University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK
| | - David A Ritchie
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Hannah J Joyce
- Centre for Advanced Photonics and Electronics, Electrical Engineering Division, University of Cambridge, Cambridge, CB3 0FA, UK
| | - Michael J Kelly
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
- Centre for Advanced Photonics and Electronics, Electrical Engineering Division, University of Cambridge, Cambridge, CB3 0FA, UK
| | - Charles G Smith
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
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Nanda G, Aguilera-Servin JL, Rakyta P, Kormányos A, Kleiner R, Koelle D, Watanabe K, Taniguchi T, Vandersypen LMK, Goswami S. Current-Phase Relation of Ballistic Graphene Josephson Junctions. Nano Lett 2017; 17:3396-3401. [PMID: 28474892 PMCID: PMC5474691 DOI: 10.1021/acs.nanolett.7b00097] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 05/03/2017] [Indexed: 05/22/2023]
Abstract
The current-phase relation (CPR) of a Josephson junction (JJ) determines how the supercurrent evolves with the superconducting phase difference across the junction. Knowledge of the CPR is essential in order to understand the response of a JJ to various external parameters. Despite the rising interest in ultraclean encapsulated graphene JJs, the CPR of such junctions remains unknown. Here, we use a fully gate-tunable graphene superconducting quantum intereference device (SQUID) to determine the CPR of ballistic graphene JJs. Each of the two JJs in the SQUID is made with graphene encapsulated in hexagonal boron nitride. By independently controlling the critical current of the JJs, we can operate the SQUID either in a symmetric or asymmetric configuration. The highly asymmetric SQUID allows us to phase-bias one of the JJs and thereby directly obtain its CPR. The CPR is found to be skewed, deviating significantly from a sinusoidal form. The skewness can be tuned with the gate voltage and oscillates in antiphase with Fabry-Pérot resistance oscillations of the ballistic graphene cavity. We compare our experiments with tight-binding calculations that include realistic graphene-superconductor interfaces and find a good qualitative agreement.
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Affiliation(s)
- G. Nanda
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA Delft, The Netherlands
| | - J. L. Aguilera-Servin
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA Delft, The Netherlands
- Institute
of Science and Technology Austria, Am Campus 1, A-3400 Klosterneuburg, Austria
| | - P. Rakyta
- Department
of Physics of Complex Systems, Eötvös
University, Pázmány Péter Sétány 1/A, H-1117 Budapest, Hungary
| | - A. Kormányos
- Department
of Physics, University of Konstanz, D-78464 Konstanz, Germany
| | - R. Kleiner
- Physikalisches
Institut and Center for Quantum Science (CQ) in LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - D. Koelle
- Physikalisches
Institut and Center for Quantum Science (CQ) in LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - K. Watanabe
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - T. Taniguchi
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - L. M. K. Vandersypen
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA Delft, The Netherlands
- QuTech, Delft University of
Technology, 2600 GA Delft, The Netherlands
| | - S. Goswami
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA Delft, The Netherlands
- QuTech, Delft University of
Technology, 2600 GA Delft, The Netherlands
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