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Olšteins D, Nagda G, Carrad DJ, Beznasyuk DV, Petersen CEN, Martí-Sánchez S, Arbiol J, Jespersen TS. Cryogenic multiplexing using selective area grown nanowires. Nat Commun 2023; 14:7738. [PMID: 38007553 PMCID: PMC10676361 DOI: 10.1038/s41467-023-43551-1] [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: 05/31/2023] [Accepted: 11/13/2023] [Indexed: 11/27/2023] Open
Abstract
Bottom-up grown nanomaterials play an integral role in the development of quantum technologies but are often challenging to characterise on large scales. Here, we harness selective area growth of semiconductor nanowires to demonstrate large-scale integrated circuits and characterisation of large numbers of quantum devices. The circuit consisted of 512 quantum devices embedded within multiplexer/demultiplexer pairs, incorporating thousands of interconnected selective area growth nanowires operating under deep cryogenic conditions. Multiplexers enable a range of new strategies in quantum device research and scaling by increasing the device count while limiting the number of connections between room-temperature control electronics and the cryogenic samples. As an example of this potential we perform a statistical characterization of large arrays of identical quantum dots thus establishing the feasibility of applying cross-bar gating strategies for efficient scaling of future selective area growth quantum circuits. More broadly, the ability to systematically characterise large numbers of devices provides new levels of statistical certainty to materials/device development.
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Affiliation(s)
- Dāgs Olšteins
- Center For Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Gunjan Nagda
- Center For Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark
| | - Damon J Carrad
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Daria V Beznasyuk
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Christian E N Petersen
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Sara Martí-Sánchez
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, Spain
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, Barcelona, Catalonia, Spain
- ICREA, Passeig de Lluís Companys 23, 08010, Barcelona, Catalonia, Spain
| | - Thomas S Jespersen
- Center For Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100, Copenhagen, Denmark.
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800, Kongens Lyngby, Denmark.
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2
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Nagda G, Beznasyuk DV, Nygård J, Jespersen TS. Effect of in-plane alignment on selective area grown homo-epitaxial nanowires. Nanotechnology 2023; 34:275702. [PMID: 37015220 DOI: 10.1088/1361-6528/acca27] [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: 02/01/2023] [Accepted: 04/04/2023] [Indexed: 06/19/2023]
Abstract
In-plane selective area growth (SAG) of III-V nanowires (NWs) has emerged as a scalable materials platform for quantum electronics and photonics applications. Most applications impose strict requirements on the material characteristics which makes optimization of the crystal quality vital. Alignment of in-plane SAG NWs with respect to the substrate symmetry is of importance due to the large substrate-NW interface as well as to obtain nanostructures with well-defined facets. Understanding the role of mis-orientation is thus important for designing devices and interpretation of electrical performance of devices. Here we study the effect of mis-orientation on morphology of selectively grown NWs oriented along the [1 1̅ 1̅] direction on GaAs(2 1 1)B. Atomic force microscopy is performed to extract facet roughness as a measure of structural quality. Further, we evaluate the dependence of material incorporation in NWs on the orientation and present the facet evolution in between two high symmetry in-plane orientations. By investigating the length dependence of NW morphology, we find that the morphology of ≈1μm long nominally aligned NWs remains unaffected by the unintentional misalignment associated with the processing and alignment of the sample under study. Finally, we show that using Sb as a surfactant during growth improves root-mean-square facet roughness for large misalignment but does not lower it for nominally aligned NWs.
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Affiliation(s)
- G Nagda
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - D V Beznasyuk
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - J Nygård
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - T S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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3
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Kousar B, Carrad DJ, Stampfer L, Krogstrup P, Nygård J, Jespersen TS. InAs/MoRe Hybrid Semiconductor/Superconductor Nanowire Devices. Nano Lett 2022; 22:8845-8851. [PMID: 36332116 DOI: 10.1021/acs.nanolett.2c02532] [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: 06/16/2023]
Abstract
Implementing superconductors capable of proximity-inducing a large energy gap in semiconductors in the presence of strong magnetic fields is a major goal toward applications of semiconductor/superconductor hybrid materials in future quantum information technologies. Here, we study the performance of devices consisting of InAs nanowires in electrical contact with molybdenum-rhenium (MoRe) superconducting alloys. The MoRe thin films exhibit transition temperatures of ∼10 K and critical fields exceeding 6 T. Normal/superconductor devices enabled tunnel spectroscopy of the corresponding induced superconductivity, which was maintained up to ∼10 K, and MoRe-based Josephson devices exhibited supercurrents and multiple Andreev reflections. We determine an induced superconducting gap lower than expected from the transition temperature and observe gap softening at finite magnetic field. These may be common features for hybrids based on large-gap, type II superconductors. The results encourage further development of MoRe-based hybrids.
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Affiliation(s)
- Bilal Kousar
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100Copenhagen, Denmark
- Univ. Grenoble Alpes, CNRS, Institut Néel, 38000Grenoble, France
| | - Damon J Carrad
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800Kgs. Lyngby, Denmark
| | - Lukas Stampfer
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100Copenhagen, Denmark
| | - Peter Krogstrup
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100Copenhagen, Denmark
| | - Jesper Nygård
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100Copenhagen, Denmark
| | - Thomas S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800Kgs. Lyngby, Denmark
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4
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Li Y, Xiang C, Chiabrera FM, Yun S, Zhang H, Kelly DJ, Dahm RT, Kirchert CKR, Cozannet TEL, Trier F, Christensen DV, Booth TJ, Simonsen SB, Kadkhodazadeh S, Jespersen TS, Pryds N. Stacking and Twisting of Freestanding Complex Oxide Thin Films. Adv Mater 2022; 34:e2203187. [PMID: 35901262 DOI: 10.1002/adma.202203187] [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] [Received: 04/08/2022] [Revised: 07/26/2022] [Indexed: 06/15/2023]
Abstract
The integration of dissimilar materials in heterostructures has long been a cornerstone of modern materials science-seminal examples are 2D materials and van der Waals heterostructures. Recently, new methods have been developed that enable the realization of ultrathin freestanding oxide films approaching the 2D limit. Oxides offer new degrees of freedom, due to the strong electronic interactions, especially the 3d orbital electrons, which give rise to rich exotic phases. Inspired by this progress, a new platform for assembling freestanding oxide thin films with different materials and orientations into artificial stacks with heterointerfaces is developed. It is shown that the oxide stacks can be tailored by controlling the stacking sequences, as well as the twist angle between the constituent layers with atomically sharp interfaces, leading to distinct moiré patterns in the transmission electron microscopy images of the full stacks. Stacking and twisting is recognized as a key degree of structural freedom in 2D materials but, until now, has never been realized for oxide materials. This approach opens unexplored avenues for fabricating artificial 3D oxide stacking heterostructures with freestanding membranes across a broad range of complex oxide crystal structures with functionalities not available in conventional 2D materials.
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Affiliation(s)
- Ying Li
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
- Hubei Province Key Laboratory of Systems Science in Metallurgical Process, Faculty of Science, Wuhan University of Science and Technology, Wuhan, 430081, P. R. China
| | - Cheng Xiang
- Department of Physics, Centre for Nanostructured Graphene (CNG), Technical University of Denmark (DTU), Fysikvej, 309, Kgs. Lyngby, 2800, Denmark
| | - Francesco M Chiabrera
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Shinhee Yun
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Haiwu Zhang
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Daniel J Kelly
- DTU Nanolab, Technical University of Denmark (DTU), Fysikvej, 307, Kgs. Lyngby, 2800, Denmark
| | - Rasmus T Dahm
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Charline K R Kirchert
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Thomas E Le Cozannet
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Felix Trier
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Dennis V Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Timothy J Booth
- Department of Physics, Centre for Nanostructured Graphene (CNG), Technical University of Denmark (DTU), Fysikvej, 309, Kgs. Lyngby, 2800, Denmark
| | - Søren B Simonsen
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Shima Kadkhodazadeh
- DTU Nanolab, Technical University of Denmark (DTU), Fysikvej, 307, Kgs. Lyngby, 2800, Denmark
| | - Thomas S Jespersen
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Fysikvej, 310, Kgs. Lyngby, 2800, Denmark
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5
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Stampfer L, Carrad DJ, Olsteins D, Petersen CEN, Khan SA, Krogstrup P, Jespersen TS. Andreev Interference in the Surface Accumulation Layer of Half-Shell InAsSb/Al Hybrid Nanowires. Adv Mater 2022; 34:e2108878. [PMID: 35050545 DOI: 10.1002/adma.202108878] [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: 11/03/2021] [Revised: 12/29/2021] [Indexed: 06/14/2023]
Abstract
Understanding the spatial distribution of charge carriers in III-V nanowires proximity coupled to superconductors is important for the design and interpretation of experiments based on hybrid quantum devices. In this letter, the gate-dependent surface accumulation layer of half-shell InAsSb/Al nanowires is studied by means of Andreev interference in a parallel magnetic field. Both uniform hybrid nanowires and devices featuring a short Josephson junction fabricated by shadow lithography, exhibit periodic modulation of the switching current. The period corresponds to a flux quantum through the nanowire diameter and is consistent with Andreev bound states occupying a cylindrical surface accumulation layer. The spatial distribution is tunable by a gate potential as expected from electrostatic models.
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Affiliation(s)
- Lukas Stampfer
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark
| | - Damon J Carrad
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark
| | - Dags Olsteins
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark
| | - Christian E N Petersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark
| | - Sabbir A Khan
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark
- Microsoft Quantum Materials Lab Copenhagen, Lyngby, 2800, Denmark
| | - Peter Krogstrup
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark
- Microsoft Quantum Materials Lab Copenhagen, Lyngby, 2800, Denmark
| | - Thomas S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, Copenhagen, 2100, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, Lyngby, 2800, Denmark
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6
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Khan SA, Stampfer L, Mutas T, Kang JH, Krogstrup P, Jespersen TS. Multiterminal Quantized Conductance in InSb Nanocrosses. Adv Mater 2021; 33:e2100078. [PMID: 34075631 DOI: 10.1002/adma.202100078] [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: 01/05/2021] [Revised: 03/15/2021] [Indexed: 06/12/2023]
Abstract
By studying the time-dependent axial and radial growth of InSb nanowires (NWs), the conditions for the synthesis of single-crystalline InSb nanocrosses (NCs) by molecular beam epitaxy are mapped. Low-temperature electrical measurements of InSb NC devices with local gate control on individual terminals exhibit quantized conductance and are used to probe the spatial distribution of the conducting channels. Tuning to a situation where the NC junction is connected by few-channel quantum point contacts in the connecting NW terminals, it is shown that transport through the junction is ballistic except close to pinch-off. Combined with a new concept for shadow-epitaxy of patterned superconductors on NCs, the structures reported here show promise for the realization of non-trivial topological states in multi-terminal Josephson junctions.
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Affiliation(s)
- Sabbir A Khan
- Microsoft Quantum Materials Lab Copenhagen, Lyngby, 2800, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Lukas Stampfer
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Timo Mutas
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Jung-Hyun Kang
- Microsoft Quantum Materials Lab Copenhagen, Lyngby, 2800, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Peter Krogstrup
- Microsoft Quantum Materials Lab Copenhagen, Lyngby, 2800, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Thomas S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, 2100, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building, Lyngby, 310, 2800, Denmark
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7
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Dahm RT, Erlandsen R, Trier F, Sambri A, Gennaro ED, Guarino A, Stampfer L, Christensen DV, Granozio FM, Jespersen TS. Size-Controlled Spalling of LaAlO 3/SrTiO 3 Micromembranes. ACS Appl Mater Interfaces 2021; 13:12341-12346. [PMID: 33661598 DOI: 10.1021/acsami.0c21612] [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: 06/12/2023]
Abstract
The ability to form freestanding oxide membranes of nanoscale thickness is of great interest for enabling material functionality and for integrating oxides in flexible electronic and photonic technologies. Recently, a route has been demonstrated for forming conducting heterostructure membranes of LaAlO3 and SrTiO3, the canonical system for oxide electronics. In this route, the epitaxial growth of LaAlO3 on SrTiO3 resulted in a strained state that relaxed by producing freestanding membranes with random sizes and locations. Here, we extend the method to enable self-formed LaAlO3/SrTiO3 micromembranes with control over membrane position, their lateral sizes from 2 to 20 μm, and with controlled transfer to other substrates of choice. This method opens up the possibility to study and use the two-dimensional electron gas in LaAlO3/SrTiO3 membranes for advanced device concepts.
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Affiliation(s)
- Rasmus T Dahm
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | - Ricci Erlandsen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | - Felix Trier
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Alessia Sambri
- CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Naples, Italy
| | - Emiliano Di Gennaro
- Dipartimento di Fisica "E. Pancini", Compl. Univ. di Monte S. Angelo, Università di Napoli "Federico II", Via Cintia, 80126 Napoli, Italy
| | - Anita Guarino
- Department of Physical Sciences and Technologies of Matter, CNR-DSFTM NFFA Trieste Area Science Park, Basovizza Strada Statale 14, 34149 Trieste, Italy
| | - Lukas Stampfer
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Dennis V Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
| | | | - Thomas S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Fysikvej, Building 310, 2800 Kgs. Lyngby, Denmark
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8
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Khan SA, Lampadaris C, Cui A, Stampfer L, Liu Y, Pauka SJ, Cachaza ME, Fiordaliso EM, Kang JH, Korneychuk S, Mutas T, Sestoft JE, Krizek F, Tanta R, Cassidy MC, Jespersen TS, Krogstrup P. Highly Transparent Gatable Superconducting Shadow Junctions. ACS Nano 2020; 14:14605-14615. [PMID: 32396328 DOI: 10.1021/acsnano.0c02979] [Citation(s) in RCA: 2] [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: 06/11/2023]
Abstract
Gate-tunable junctions are key elements in quantum devices based on hybrid semiconductor-superconductor materials. They serve multiple purposes ranging from tunnel spectroscopy probes to voltage-controlled qubit operations in gatemon and topological qubits. Common to all is that junction transparency plays a critical role. In this study, we grow single-crystalline InAs, InSb, and InAs1-xSbx semiconductor nanowires with epitaxial Al, Sn, and Pb superconductors and in situ shadowed junctions in a single-step molecular beam epitaxy process. We investigate correlations between fabrication parameters, junction morphologies, and electronic transport properties of the junctions and show that the examined in situ shadowed junctions are of significantly higher quality than the etched junctions. By varying the edge sharpness of the shadow junctions, we show that the sharpest edges yield the highest junction transparency for all three examined semiconductors. Further, critical supercurrent measurements reveal an extraordinarily high ICRN, close to the KO-2 limit. This study demonstrates a promising engineering path toward reliable gate-tunable superconducting qubits.
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Affiliation(s)
- Sabbir A Khan
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Charalampos Lampadaris
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Ajuan Cui
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Lukas Stampfer
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Yu Liu
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Sebastian J Pauka
- Microsoft Quantum Sydney, The University of Sydney, Sydney, NSW 2006, Australia
| | - Martin E Cachaza
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | | | - Jung-Hyun Kang
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Svetlana Korneychuk
- QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands
| | - Timo Mutas
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Joachim E Sestoft
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Filip Krizek
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Rawa Tanta
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Maja C Cassidy
- Microsoft Quantum Sydney, The University of Sydney, Sydney, NSW 2006, Australia
| | - Thomas S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Peter Krogstrup
- Microsoft Quantum Materials Lab Copenhagen, 2800 Lyngby, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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9
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Luthi F, Stavenga T, Enzing OW, Bruno A, Dickel C, Langford NK, Rol MA, Jespersen TS, Nygård J, Krogstrup P, DiCarlo L. Evolution of Nanowire Transmon Qubits and Their Coherence in a Magnetic Field. Phys Rev Lett 2018; 120:100502. [PMID: 29570312 DOI: 10.1103/physrevlett.120.100502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Indexed: 06/08/2023]
Abstract
We present an experimental study of flux- and gate-tunable nanowire transmons with state-of-the-art relaxation time allowing quantitative extraction of flux and charge noise coupling to the Josephson energy. We evidence coherence sweet spots for charge, tuned by voltage on a proximal side gate, where first order sensitivity to switching two-level systems and background 1/f noise is minimized. Next, we investigate the evolution of a nanowire transmon in a parallel magnetic field up to 70 mT, the upper bound set by the closing of the induced gap. Several features observed in the field dependence of qubit energy relaxation and dephasing times are not fully understood. Using nanowires with a thinner, partially covering Al shell will enable operation of these circuits up to 0.5 T, a regime relevant for topological quantum computation and other applications.
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Affiliation(s)
- F Luthi
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - T Stavenga
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - O W Enzing
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - A Bruno
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - C Dickel
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - N K Langford
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - M A Rol
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - T S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - J Nygård
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
- Nano-Science Center, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - P Krogstrup
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - L DiCarlo
- QuTech, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, Netherlands
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10
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Prawiroatmodjo GEDK, Leijnse M, Trier F, Chen Y, Christensen DV, von Soosten M, Pryds N, Jespersen TS. Transport and excitations in a negative-U quantum dot at the LaAlO 3/SrTiO 3 interface. Nat Commun 2017; 8:395. [PMID: 28855569 PMCID: PMC5577219 DOI: 10.1038/s41467-017-00495-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 07/03/2017] [Indexed: 11/20/2022] Open
Abstract
In a solid-state host, attractive electron-electron interactions can lead to the formation of local electron pairs which play an important role in the understanding of prominent phenomena such as high T c superconductivity and the pseudogap phase. Recently, evidence of a paired ground state without superconductivity was demonstrated at the level of single electrons in quantum dots at the interface of LaAlO3 and SrTiO3. Here, we present a detailed study of the excitation spectrum and transport processes of a gate-defined LaAlO3/SrTiO3 quantum dot exhibiting pairing at low temperatures. For weak tunneling, the spectrum agrees with calculations based on the Anderson model with a negative effective charging energy U, and exhibits an energy gap corresponding to the Zeeman energy of the magnetic pair-breaking field. In contrast, for strong coupling, low-bias conductance is enhanced with a characteristic dependence on temperature, magnetic field and chemical potential consistent with the charge Kondo effect.Complex oxide devices provide a platform for studying and making use of strongly correlated electronic behavior. Here the authors present a LaAlO3/SrTiO3 quantum dot and show that its transport behavior is consistent with the presence of attractive electron interactions and the charge Kondo effect.
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Affiliation(s)
- Guenevere E D K Prawiroatmodjo
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Martin Leijnse
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
- Division of Solid State Physics and NanoLund, Lund University, Box 118, SE-221 00, Lund, Sweden
| | - Felix Trier
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Yunzhong Chen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Dennis V Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Merlin von Soosten
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
| | - Thomas S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark.
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11
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Albrecht SM, Hansen EB, Higginbotham AP, Kuemmeth F, Jespersen TS, Nygård J, Krogstrup P, Danon J, Flensberg K, Marcus CM. Transport Signatures of Quasiparticle Poisoning in a Majorana Island. Phys Rev Lett 2017; 118:137701. [PMID: 28409973 DOI: 10.1103/physrevlett.118.137701] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Indexed: 06/07/2023]
Abstract
We investigate effects of quasiparticle poisoning in a Majorana island with strong tunnel coupling to normal-metal leads. In addition to the main Coulomb blockade diamonds, "shadow" diamonds appear, shifted by 1e in gate voltage, consistent with transport through an excited (poisoned) state of the island. Comparison to a simple model yields an estimate of parity lifetime for the strongly coupled island (∼1 μs) and sets a bound for a weakly coupled island (>10 μs). Fluctuations in the gate-voltage spacing of Coulomb peaks at high field, reflecting Majorana hybridization, are enhanced by the reduced lever arm at strong coupling. When converted from gate voltage to energy units, fluctuations are consistent with previous measurements.
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Affiliation(s)
- S M Albrecht
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - E B Hansen
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - A P Higginbotham
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
- JILA, University of Colorado and NIST, Boulder, Colorado 80309, USA
| | - F Kuemmeth
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - T S Jespersen
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - J Nygård
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - P Krogstrup
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - J Danon
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
- Department of Physics, NTNU, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - K Flensberg
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - C M Marcus
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
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12
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Tanta R, Kanne T, Amaduzzi F, Liao Z, Madsen MH, Alarcón-Lladó E, Krogstrup P, Johnson E, Morral AFI, Vosch T, Nygård J, Jespersen TS. Morphology and composition of oxidized InAs nanowires studied by combined Raman spectroscopy and transmission electron microscopy. Nanotechnology 2016; 27:305704. [PMID: 27323001 DOI: 10.1088/0957-4484/27/30/305704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Any device exposed to ambient conditions will be prone to oxidation. This may be of particular importance for semiconductor nanowires because of the high surface-to-volume ratio and only little is known about the consequences of oxidation for these systems. Here, we study the properties of indium arsenide nanowires which were locally oxidized using a focused laser beam. Polarization dependent micro-Raman measurements confirmed the presence of crystalline arsenic, and transmission electron microscopy diffraction showed the presence of indium oxide. The surface dependence of the oxidation was investigated in branched nanowires grown along the [Formula: see text] and [Formula: see text] wurtzite crystal directions exhibiting different surface facets. The oxidation did not occur at the [Formula: see text] direction. The origin of this selectivity is discussed in terms transition state kinetics of the free surfaces of the different crystal families of the facets and numerical simulations of the laser induced heating.
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Affiliation(s)
- Rawa Tanta
- Center for Quantum Devices & Nano Science Center, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
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13
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Larsen TW, Petersson KD, Kuemmeth F, Jespersen TS, Krogstrup P, Nygård J, Marcus CM. Semiconductor-Nanowire-Based Superconducting Qubit. Phys Rev Lett 2015; 115:127001. [PMID: 26431009 DOI: 10.1103/physrevlett.115.127001] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Indexed: 06/05/2023]
Abstract
We introduce a hybrid qubit based on a semiconductor nanowire with an epitaxially grown superconductor layer. Josephson energy of the transmonlike device ("gatemon") is controlled by an electrostatic gate that depletes carriers in a semiconducting weak link region. Strong coupling to an on-chip microwave cavity and coherent qubit control via gate voltage pulses is demonstrated, yielding reasonably long relaxation times (~0.8 μs) and dephasing times (~1 μs), exceeding gate operation times by 2 orders of magnitude, in these first-generation devices. Because qubit control relies on voltages rather than fluxes, dissipation in resistive control lines is reduced, screening reduces cross talk, and the absence of flux control allows operation in a magnetic field, relevant for topological quantum information.
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Affiliation(s)
- T W Larsen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - K D Petersson
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - F Kuemmeth
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - T S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - P Krogstrup
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - J Nygård
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
- Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
| | - C M Marcus
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark
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14
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Chen YZ, Trier F, Wijnands T, Green RJ, Gauquelin N, Egoavil R, Christensen DV, Koster G, Huijben M, Bovet N, Macke S, He F, Sutarto R, Andersen NH, Sulpizio JA, Honig M, Prawiroatmodjo GEDK, Jespersen TS, Linderoth S, Ilani S, Verbeeck J, Van Tendeloo G, Rijnders G, Sawatzky GA, Pryds N. Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces by charge-transfer-induced modulation doping. Nat Mater 2015; 14:801-806. [PMID: 26030303 DOI: 10.1038/nmat4303] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 04/22/2015] [Indexed: 06/04/2023]
Abstract
Two-dimensional electron gases (2DEGs) formed at the interface of insulating complex oxides promise the development of all-oxide electronic devices. These 2DEGs involve many-body interactions that give rise to a variety of physical phenomena such as superconductivity, magnetism, tunable metal-insulator transitions and phase separation. Increasing the mobility of the 2DEG, however, remains a major challenge. Here, we show that the electron mobility is enhanced by more than two orders of magnitude by inserting a single-unit-cell insulating layer of polar La(1-x)Sr(x)MnO3 (x = 0, 1/8, and 1/3) at the interface between disordered LaAlO3 and crystalline SrTiO3 produced at room temperature. Resonant X-ray spectroscopy and transmission electron microscopy show that the manganite layer undergoes unambiguous electronic reconstruction, leading to modulation doping of such atomically engineered complex oxide heterointerfaces. At low temperatures, the modulation-doped 2DEG exhibits Shubnikov-de Haas oscillations and fingerprints of the quantum Hall effect, demonstrating unprecedented high mobility and low electron density.
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Affiliation(s)
- Y Z Chen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - F Trier
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - T Wijnands
- Faculty of Science and Technology and MESA + Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
| | - R J Green
- 1] Quantum Matter Institute, Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Max Planck Institute for Chemical Physics of Solids, Nöthnitzerstraße 40, 01187 Dresden, Germany
| | - N Gauquelin
- EMAT, University of Antwerp, Groenenborgerlaan 171 2020 Antwerp, Belgium
| | - R Egoavil
- EMAT, University of Antwerp, Groenenborgerlaan 171 2020 Antwerp, Belgium
| | - D V Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - G Koster
- Faculty of Science and Technology and MESA + Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
| | - M Huijben
- Faculty of Science and Technology and MESA + Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
| | - N Bovet
- Nano-Science Center, Department of Chemistry, University of Copenhagen, 2100 Copenhagen, Denmark
| | - S Macke
- 1] Quantum Matter Institute, Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada [2] Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - F He
- Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - R Sutarto
- Canadian Light Source, Saskatoon, Saskatchewan S7N 2V3, Canada
| | - N H Andersen
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark
| | - J A Sulpizio
- Department of Condensed Matter Physics, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - M Honig
- Department of Condensed Matter Physics, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - G E D K Prawiroatmodjo
- Center for Quantum devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - T S Jespersen
- Center for Quantum devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - S Linderoth
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - S Ilani
- Department of Condensed Matter Physics, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - J Verbeeck
- EMAT, University of Antwerp, Groenenborgerlaan 171 2020 Antwerp, Belgium
| | - G Van Tendeloo
- EMAT, University of Antwerp, Groenenborgerlaan 171 2020 Antwerp, Belgium
| | - G Rijnders
- Faculty of Science and Technology and MESA + Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands
| | - G A Sawatzky
- Quantum Matter Institute, Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - N Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
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15
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Krogstrup P, Ziino NLB, Chang W, Albrecht SM, Madsen MH, Johnson E, Nygård J, Marcus CM, Jespersen TS. Epitaxy of semiconductor-superconductor nanowires. Nat Mater 2015; 14:400-6. [PMID: 25581626 DOI: 10.1038/nmat4176] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Accepted: 11/18/2014] [Indexed: 05/05/2023]
Abstract
Controlling the properties of semiconductor/metal interfaces is a powerful method for designing functionality and improving the performance of electrical devices. Recently semiconductor/superconductor hybrids have appeared as an important example where the atomic scale uniformity of the interface plays a key role in determining the quality of the induced superconducting gap. Here we present epitaxial growth of semiconductor-metal core-shell nanowires by molecular beam epitaxy, a method that provides a conceptually new route to controlled electrical contacting of nanostructures and the design of devices for specialized applications such as topological and gate-controlled superconducting electronics. Our materials of choice, InAs/Al grown with epitaxially matched single-plane interfaces, and alternative semiconductor/metal combinations allowing epitaxial interface matching in nanowires are discussed. We formulate the grain growth kinetics of the metal phase in general terms of continuum parameters and bicrystal symmetries. The method realizes the ultimate limit of uniform interfaces and seems to solve the soft-gap problem in superconducting hybrid structures.
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Affiliation(s)
- P Krogstrup
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - N L B Ziino
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - W Chang
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - S M Albrecht
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - M H Madsen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - E Johnson
- 1] Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark [2] Department of Wind Energy, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - J Nygård
- 1] Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark [2] Nano-Science Center, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - C M Marcus
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - T S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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16
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Chang W, Albrecht SM, Jespersen TS, Kuemmeth F, Krogstrup P, Nygård J, Marcus CM. Hard gap in epitaxial semiconductor-superconductor nanowires. Nat Nanotechnol 2015; 10:232-236. [PMID: 25581886 DOI: 10.1038/nnano.2014.306] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 11/18/2014] [Indexed: 06/04/2023]
Abstract
Many present and future applications of superconductivity would benefit from electrostatic control of carrier density and tunnelling rates, the hallmark of semiconductor devices. One particularly exciting application is the realization of topological superconductivity as a basis for quantum information processing. Proposals in this direction based on the proximity effect in semiconductor nanowires are appealing because the key ingredients are currently in hand. However, previous instances of proximitized semiconductors show significant tunnelling conductance below the superconducting gap, suggesting a continuum of subgap states--a situation that nullifies topological protection. Here, we report a hard superconducting gap induced by the proximity effect in a semiconductor, using epitaxial InAs-Al semiconductor-superconductor nanowires. The hard gap, together with favourable material properties and gate-tunability, makes this new hybrid system attractive for a number of applications, as well as fundamental studies of mesoscopic superconductivity.
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Affiliation(s)
- W Chang
- 1] Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark [2] Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - S M Albrecht
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - T S Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - F Kuemmeth
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - P Krogstrup
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - J Nygård
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - C M Marcus
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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17
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Chang W, Manucharyan VE, Jespersen TS, Nygård J, Marcus CM. Tunneling spectroscopy of quasiparticle bound states in a spinful Josephson junction. Phys Rev Lett 2013; 110:217005. [PMID: 23745916 DOI: 10.1103/physrevlett.110.217005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Indexed: 06/02/2023]
Abstract
The spectrum of a segment of InAs nanowire, confined between two superconducting leads, was measured as function of gate voltage and superconducting phase difference using a third normal-metal tunnel probe. Subgap resonances for odd electron occupancy-interpreted as bound states involving a confined electron and a quasiparticle from the superconducting leads, reminiscent of Yu-Shiba-Rusinov states-evolve into Kondo-related resonances at higher magnetic fields. An additional zero-bias peak of unknown origin is observed to coexist with the quasiparticle bound states.
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Affiliation(s)
- W Chang
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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18
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Jespersen TS, Grove-Rasmussen K, Flensberg K, Paaske J, Muraki K, Fujisawa T, Nygård J. Gate-dependent orbital magnetic moments in carbon nanotubes. Phys Rev Lett 2011; 107:186802. [PMID: 22107661 DOI: 10.1103/physrevlett.107.186802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Indexed: 05/31/2023]
Abstract
We investigate how the orbital magnetic moments of electron and hole states in a carbon nanotube quantum dot depend on the number of carriers on the dot. Low temperature transport measurements are carried out in a setup where the device can be rotated in an applied magnetic field, thus enabling accurate alignment with the nanotube axis. The field dependence of the level structure is measured by excited state spectroscopy and excellent correspondence with a single-particle calculation is found. In agreement with band structure calculations we find a decrease of the orbital magnetic moment with increasing electron or hole occupation of the dot, with a scale given by the band gap of the nanotube.
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Affiliation(s)
- T S Jespersen
- Niels Bohr Institute & Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
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19
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Csonka S, Hofstetter L, Freitag F, Oberholzer S, Schönenberger C, Jespersen TS, Aagesen M, Nygård J. Giant fluctuations and gate control of the g-factor in InAs nanowire quantum dots. Nano Lett 2008; 8:3932-3935. [PMID: 18937519 DOI: 10.1021/nl802418w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We study the g-factor of discrete electron states in InAs nanowire based quantum dots. The g values are determined from the magnetic field splitting of the zero bias anomaly due to the spin 1/2 Kondo effect. Unlike to previous studies based on 2DEG quantum dots, the g-factors of neighboring electron states show a surprisingly large fluctuation: g can scatter between 2 and 18. Furthermore electric gate tunability of the g-factor is demonstrated.
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Affiliation(s)
- S Csonka
- Department of Physics, University of Basel, Klingelbergstr. 82, CH-4056 Basel, Switzerland.
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