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Matsuo S, Imoto T, Yokoyama T, Sato Y, Lindemann T, Gronin S, Gardner GC, Nakosai S, Tanaka Y, Manfra MJ, Tarucha S. Phase-dependent Andreev molecules and superconducting gap closing in coherently-coupled Josephson junctions. Nat Commun 2023; 14:8271. [PMID: 38092786 PMCID: PMC10719386 DOI: 10.1038/s41467-023-44111-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 11/30/2023] [Indexed: 12/17/2023] Open
Abstract
The Josephson junction (JJ) is an essential element of superconducting (SC) devices for both fundamental and applied physics. The short-range coherent coupling of two adjacent JJs forms Andreev molecule states (AMSs), which provide a new ingredient to engineer exotic SC phenomena such as topological SC states and Andreev qubits. Here we provide tunneling spectroscopy measurements on a device consisting of two electrically controllable planar JJs sharing a single SC electrode. We discover that Andreev spectra in the coupled JJ are highly modulated from those in the single JJs and possess phase-dependent AMS features reproduced in our numerical calculation. Notably, the SC gap closing due to the AMS formation is experimentally observed. Our results help in understanding SC transport derived from the AMS and promoting the use of AMS physics to engineer topological SC states and quantum information devices.
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Affiliation(s)
- Sadashige Matsuo
- Center for Emergent Matter Science, RIKEN, Saitama, 351-0198, Japan.
| | - Takaya Imoto
- Center for Emergent Matter Science, RIKEN, Saitama, 351-0198, Japan
- Department of Applied Physics, Tokyo University of Science, Tokyo, 162-8601, Japan
| | - Tomohiro Yokoyama
- Department of Materials Engineering Science, Osaka University, Osaka, 560-8531, Japan.
| | - Yosuke Sato
- Center for Emergent Matter Science, RIKEN, Saitama, 351-0198, Japan
| | - Tyler Lindemann
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana, IN, 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, IN, 47907, USA
| | - Sergei Gronin
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, IN, 47907, USA
| | - Geoffrey C Gardner
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, IN, 47907, USA
| | - Sho Nakosai
- Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
| | - Yukio Tanaka
- Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
| | - Michael J Manfra
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana, IN, 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, IN, 47907, USA
- School of Materials Engineering, Purdue University, West Lafayette, Indiana, IN, 47907, USA
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, IN, 47907, USA
| | - Seigo Tarucha
- Center for Emergent Matter Science, RIKEN, Saitama, 351-0198, Japan.
- RIKEN Center for Quantum Computing, RIKEN, Saitama, 351-0198, Japan.
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2
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Gupta M, Graziano GV, Pendharkar M, Dong JT, Dempsey CP, Palmstrøm C, Pribiag VS. Gate-tunable superconducting diode effect in a three-terminal Josephson device. Nat Commun 2023; 14:3078. [PMID: 37248246 DOI: 10.1038/s41467-023-38856-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 05/11/2023] [Indexed: 05/31/2023] Open
Abstract
The phenomenon of non-reciprocal critical current in a Josephson device, termed the Josephson diode effect, has garnered much recent interest. Realization of the diode effect requires inversion symmetry breaking, typically obtained by spin-orbit interactions. Here we report observation of the Josephson diode effect in a three-terminal Josephson device based upon an InAs quantum well two-dimensional electron gas proximitized by an epitaxial aluminum superconducting layer. We demonstrate that the diode efficiency in our devices can be tuned by a small out-of-plane magnetic field or by electrostatic gating. We show that the Josephson diode effect in these devices is a consequence of the artificial realization of a current-phase relation that contains higher harmonics. We also show nonlinear DC intermodulation and simultaneous two-signal rectification, enabled by the multi-terminal nature of the devices. Furthermore, we show that the diode effect is an inherent property of multi-terminal Josephson devices, establishing an immediately scalable approach by which potential applications of the Josephson diode effect can be realized, agnostic to the underlying material platform. These Josephson devices may also serve as gate-tunable building blocks in designing topologically protected qubits.
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Affiliation(s)
- Mohit Gupta
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Gino V Graziano
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Mihir Pendharkar
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Jason T Dong
- Materials Department, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Connor P Dempsey
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Chris Palmstrøm
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- Materials Department, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- California NanoSystems Institute, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Vlad S Pribiag
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
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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 LETTERS 2023. [PMID: 37191404 DOI: 10.1021/acs.nanolett.3c01276] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [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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Selective control of conductance modes in multi-terminal Josephson junctions. Nat Commun 2022; 13:5933. [PMID: 36209199 PMCID: PMC9547902 DOI: 10.1038/s41467-022-33682-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 09/29/2022] [Indexed: 11/18/2022] Open
Abstract
The Andreev bound state spectra of multi-terminal Josephson junctions form an artificial band structure, which is predicted to host tunable topological phases under certain conditions. However, the number of conductance modes between the terminals of a multi-terminal Josephson junction must be few in order for this spectrum to be experimentally accessible. In this work, we employ a quantum point contact geometry in three-terminal Josephson devices to demonstrate independent control of conductance modes between each pair of terminals and access to the single-mode regime coexistent with the presence of superconducting coupling. These results establish a full platform on which to realize tunable Andreev bound state spectra in multi-terminal Josephson junctions. Multiterminal Josephson junctions may provide a novel way to realize topologically non-trivial band structures in an n-dimensional phase space. Here, the authors experimentally demonstrate the proposed necessary conditions to measure these states.
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