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Gate-tunable Josephson diode in proximitized InAs supercurrent interferometers

Physical Review Research 2023年第3期5卷 033131-033131页

作者： Carlo Ciaccia Roy Haller Asbjørn C. C. Drachmann Tyler Lindemann Michael J. Manfra Constantin Schrade Christian Schönenberger Quantum- and Nanoelectronics Lab Department of Physics University of Basel 4056 Basel Switzerland Center for Quantum Devices Niels Bohr Institute University of Copenhagen 2100 Copenhagen Denmark NNF Quantum Computing Programme Niels Bohr Institute University of Copenhagen 2100 Copenhagen Denmark Department of Physics and Astronomy Purdue University West Lafayette Indiana 47907 USA Birck Nanotechnology Center Purdue University West Lafayette Indiana 47907 USA Elmore Family School of Electrical and Computer Engineering Purdue University West Lafayette Indiana 47907 USA School of Materials Engineering Purdue University West Lafayette Indiana 47907 USA Swiss Nanoscience Institute University of Basel 4056 Basel Switzerland

The Josephson diode (JD) is a nonreciprocal circuit element that supports a larger critical current in one direction compared to the other. This effect has gained growing interest because of promising applications in superconducting electronic circuits with low power consumption. Some implementations of a JD rely on breaking the inversion symmetry in the material used to realize Josephson junctions (JJs), but recent theoretical proposals have suggested that the effect can also be engineered by combining two JJs hosting highly transmitting Andreev bound states in a Superconducting quantum Interference Device (SQUID) at a small, but finite flux bias. We have realized a SQUID with two JJs fabricated in a proximitized InAs two-dimensional electron gas (2DEG). We demonstrate gate control of the diode efficiency from zero up to around 30% at specific flux bias values which comes close to the maximum of ∼40% predicated in Souto et al. [Phys. Rev. Lett. 129, 267702 (2022)]. The key ingredients to the JD effect in the SQUID arrangement is the presence of highly transmitting channels in the JJs, a flux bias, and an asymmetry between the two SQUID arms.

关键词： Non-reciprocal transmission Proximity effect quantum transport Diodes III-V semiconductors Josephson junctions SQUID Superconducting devices Interferometry Microwave techniques

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Ground state phase diagram and "parity flipping" microwave transitions in a gate-tunable Josephson Junction

arXiv

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arXiv 2023年

作者： Sahu, M.R. Matute-Cañadas, F.J. Benito, M. Krogstrup, P. Nygård, J. Goffman, M.F. Urbina, C. Levy Yeyati, A. Pothier, H. Quantronics Group Service de Physique de l'État Condensé CNRS UMR 3680 IRAMIS CEA-Saclay Université Paris-Saclay Gif-sur-Yvette91191 France Instituto Nicolás Cabrera Universidad Autónoma de Madrid Madrid28049 Spain NNF Quantum Computing Programme Niels Bohr Institute University of Copenhagen Universitetsparken 5 Copenhagen2100 Denmark Center for Quantum Devices Niels Bohr Institute University of Copenhagen Universitetsparken 5 Copenhagen2100 Denmark

We probed a gate-tunable InAs nanowire Josephson weak link by coupling it to a microwave resonator. Tracking the resonator frequency shift when the weak link is close to pinch-off, we observe that the ground state of the latter alternates between a singlet and a doublet when varying either the gate voltage or the superconducting phase difference across it. The corresponding microwave absorption spectra display lines that approach zero energy close to the singlet-doublet boundaries, suggesting parity flipping transitions, which are in principle forbidden in microwave spectroscopy and expected to arise only in tunnel spectroscopy. We tentatively interpret them by means of an ancillary state isolated in the junction acting as a reservoir for individual electrons. Copyright © 2023, The Authors. All rights reserved.

关键词： Microwave resonators

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Modular Autonomous Virtualization System for Two-Dimensional Semiconductor quantum Dot Arrays

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Physical Review X 2025年第2期15卷 021034-021034页

作者： Anantha S. Rao Donovan Buterakos Barnaby van Straaten Valentin John Cécile X. Yu Stefan D. Oosterhout Lucas Stehouwer Giordano Scappucci Menno Veldhorst Francesco Borsoi Justyna P. Zwolak Joint Center for Quantum Information and Computer Science University of Maryland College Park Maryland 20742 USA Department of Physics University of Maryland College Park Maryland 20742 USA National Institute of Standards and Technology Gaithersburg Maryland 20899 USA QuTech and Kavli Institute of Nanoscience Delft University of Technology P.O. Box 5046 2600 GA Delft The Netherlands QuTech and Netherlands Organisation for Applied Scientific Research (TNO) Delft The Netherlands Present address: NNF Quantum Computing Programme Niels Bohr Institute University of Copenhagen Blegdamsvej 17 2100 Copenhagen Denmark.

Arrays of gate-defined semiconductor quantum dots are among the leading candidates for building scalable quantum processors. High-fidelity initialization, control, and readout of spin qubit registers require exquisite and targeted control over key Hamiltonian parameters that define the electrostatic environment. However, due to the tight gate pitch, capacitive crosstalk between gates hinders independent tuning of chemical potentials and interdot couplings. While virtual gates offer a practical solution, determining all the required cross-capacitance matrices accurately and efficiently in large quantum dot registers is an open challenge. Here, we establish a modular automated virtualization system (MAViS)—a general and modular framework for autonomously constructing a complete stack of multilayer virtual gates in real time. Our method employs machine learning techniques to rapidly extract features from two-dimensional charge stability diagrams. We then utilize computer vision and regression models to self-consistently determine all relative capacitive couplings necessary for virtualizing plunger and barrier gates in both low- and high-tunnel-coupling regimes. Using MAViS, we successfully demonstrate accurate virtualization of a dense two-dimensional array comprising ten quantum dots defined in a high-quality Ge/SiGe heterostructure. Our work offers an elegant and practical solution for the efficient control of large-scale semiconductor quantum dot systems.

关键词： Semiconductor quantum dots

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Charge-4e supercurrent in a two-dimensional InAs-Al superconductor-semiconductor heterostructure

arXiv

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arXiv 2023年

作者： Ciaccia, Carlo Haller, Roy Drachmann, Asbjørn C.C. Lindemann, Tyler Manfra, Michael J. Schrade, Constantin Schönenberger, Christian Quantum- and Nanoelectronics Lab University of Basel BaselCH-4056 Switzerland Center for Quantum Devices Niels Bohr Institute University of Copenhagen Copenhagen2100 Denmark NNF Quantum Computing Programme Niels Bohr Institute University of Copenhagen Copenhagen2100 Denmark Department of Physics and Astronomy Purdue University West LafayetteIN47907 United States Birck Nanotechnology Center Purdue University West LafayetteIN47907 United States School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States School of Materials Engineering Purdue University West LafayetteIN47907 United States Swiss Nanoscience Institute University of Basel Klingelbergstrasse 82 Basel Switzerland

Superconducting qubits with intrinsic noise protection offer a promising approach to improve the coherence of quantum information. Crucial to such protected qubits is the encoding of the logical quantum states into wavefunctions with disjoint support. Such encoding can be achieved by a Josephson element with an unusual charge-4e supercurrent emerging from the coherent transfer of pairs of Cooper-pairs. In this work, we demonstrate the controlled conversion of a conventional charge-2e dominated to a charge-4e dominated supercurrent in a superconducting quantum interference device (SQUID) consisting of gate-tunable planar Josephson junctions. We investigate the ac Josephson effect of the SQUID and measure a dominant photon emission at twice the fundamental Josephson frequency together with a doubling of the number of Shapiro steps, both consistent with the appearance of charge-4e supercurrent. Our results present a step towards novel protected superconducting qubits based on superconductor-semiconductor hybrid materials. Copyright © 2023, The Authors. All rights reserved.

关键词： SQUIDs

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Microwave spectroscopy of interacting Andreev spins

引用

Physical Review B 2024年第4期109卷 045302-045302页

作者： J. J. Wesdorp F. J. Matute-Cañadas A. Vaartjes L. Grünhaupt T. Laeven S. Roelofs L. J. Splitthoff M. Pita-Vidal A. Bargerbos D. J. van Woerkom P. Krogstrup L. P. Kouwenhoven C. K. Andersen A. Levy Yeyati B. van Heck G. de Lange QuTech and Kavli Institute of Nanoscience Delft University of Technology 2628 CJ Delft The Netherlands Departamento de Física Teórica de la Materia Condensada Condensed Matter Physics Center (IFIMAC) and Instituto Nicolás Cabrera Universidad Autónoma de Madrid 28049 Madrid Spain Microsoft Quantum Lab Delft 2628 CJ Delft The Netherlands NNF Quantum Computing Programme Niels Bohr Institute University of Copenhagen 2100 Copenhagen Denmark Leiden Institute of Physics Universiteit Leiden Niels Bohrweg 2 2333 CA Leiden The Netherlands Dipartimento di Fisica Sapienza Università di Roma P.le Aldo Moro 2 00185 Roma Italy

Andreev bound states are fermionic states localized in weak links between superconductors which can be occupied with spinful quasiparticles. Microwave experiments using superconducting circuits with InAs/Al nanowire Josephson junctions have recently enabled probing and coherent manipulation of Andreev states but have remained limited to zero or small magnetic fields. Here, we use a flux-tunable superconducting circuit compatible in magnetic fields up to 1T to perform spectroscopy of spin-polarized Andreev states up to ∼250mT, beyond which the spectrum becomes gapless. We identify singlet and triplet states of two quasiparticles occupying different Andreev states through their dispersion in magnetic field. These states are split by exchange interaction and couple via spin-orbit coupling, analogously to two-electron states in quantum dots. We also show that the magnetic field allows to drive a direct spin-flip transition of a single quasiparticle trapped in the junction. Finally, we measure a gate- and field-dependent anomalous phase shift of the Andreev spectrum, of magnitude up to ∼0.7π. Our observations demonstrate alternative ways to manipulate Andreev states in a magnetic field and reveal spin-polarized triplet states that carry supercurrent.

关键词： Andreev reflection Circuit quantum electrodynamics Hybrid quantum systems Josephson effect quantum information with hybrid systems Spin-triplet pairing Superconductivity Josephson junctions Nanowires SQUID Semiconductors Unconventional superconductors Weak links Spin Spectroscopy

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Gate Tunable Josephson Diode in Proximitized InAs Supercurrent Interferometers

arXiv

引用

arXiv 2023年

作者： Ciaccia, Carlo Haller, Roy Drachmann, Asbjørn C.C. Lindemann, Tyler Manfra, Michael J. Schrade, Constantin Schönenberger, Christian Quantum- and Nanoelectronics Lab Department of Physics University of Basel Basel4056 Switzerland Center for Quantum Devices Niels Bohr Institute University of Copenhagen Copenhagen2100 Denmark NNF Quantum Computing Programme Niels Bohr Institute University of Copenhagen Copenhagen2100 Denmark Department of Physics and Astronomy Purdue University West LafayetteIN47907 United States Birck Nanotechnology Center Purdue University West LafayetteIN47907 United States Elmore Family School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States School of Materials Engineering Purdue University West LafayetteIN47907 United States Swiss Nanoscience Institute University of Basel Basel4056 Switzerland

The Josephson diode (JD) is a non-reciprocal circuit element that supports a larger critical current in one direction compared to the other. This effect has gained a growing interest because of promising applications in superconducting electronic circuits with low power consumption. Some implementations of a JD rely on breaking the inversion symmetry in the material used to realize Josephson junctions (JJs), but recent theoretical proposals have suggested that the effect can also be engineered by combining two JJs hosting highly transmitting Andreev bound states in a Superconducting quantum Interference Device (SQUID) at a small, but finite flux bias. We have realized a SQUID with two JJs fabricated in a proximitized InAs two-dimensional electron gas (2DEG). We demonstrate gate control of the diode efficiency from zero up to around 30% at specific flux bias values which comes close to the maximum of ∼ 40% predicated in Ref. [R. S. Souto, M. Leijnse and C. Schrade, Phys. Rev. Lett. 129, 267702 (2022)]. The key ingredients to the JD effect in the SQUID arrangement is the presence of highly transmitting channels in the JJs, a flux bias and an asymmetry between the two SQUID arms. © 2023, CC BY.

关键词： SQUIDs

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High-threshold quantum computing by fusing one-dimensional cluster states

arXiv

引用

arXiv 2022年

作者： Paesani, Stefano Brown, Benjamin J. Niels Bohr Institute University of Copenhagen Blegdamsvej 17 Copenhagen2100 Denmark NNF Quantum Computing Programme Niels Bohr Institute University of Copenhagen Denmark IBM Quantum T. J. Watson Research Center Yorktown HeightsNY10598 United States IBM Denmark Prøvensvej 1 Brøndby2605 Denmark

We propose a measurement-based model for fault-tolerant quantum computation that can be realised with one-dimensional cluster states and fusion measurements only;basic resources that are readily available with scalable photonic hardware. Our simulations demonstrate high thresholds compared with other measurement-based models realized with basic entangled resources and two-qubit fusion measurements. Its high tolerance to noise indicates that our practical construction offers a promising route to scalable quantum computing with quantum emitters and linear-optical elements. Copyright © 2022, The Authors. All rights reserved.

关键词： Cluster computing

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Cavity spectroscopy for strongly correlated systems

arXiv

引用

arXiv 2024年

作者： Grunwald, Lukas Boström, Emil Viñas Svendsen, Mark Kamper Kennes, Dante M. Rubio, Angel Institut für Theorie der Statistischen Physik RWTH Aachen University JARA-Fundamentals of Future Information Technology Aachen52056 Germany Luruper Chaussee 149 Hamburg22761 Germany Nano-Bio Spectroscopy Group Departamento de Física de Materiales Universidad del País Vasco San Sebastian20018 Spain NNF Quantum Computing Programme Niels Bohr Institute Universitetsparken 5 Copenhagen2100 Denmark Center for Computational Quantum Physics Flatiron Institute Simons Foundation New York CityNY10010 United States

Embedding materials in optical cavities has emerged as an intriguing perspective for controlling quantum materials, but a key challenge lies in measuring properties of the embedded matter. Here, we propose a framework for probing strongly correlated cavity-embedded materials through direct measurements of cavity photons. We derive general relations between photon and matter observables inside the cavity, and show how these can be measured via the emitted photons. As an example, we demonstrate how the entanglement phase transition of an embedded H2 molecule can be accessed by measuring the cavity photon occupation, and showcase how dynamical spin correlation functions can be accessed by measuring dynamical photon correlation functions. Our framework provides an all-optical method to measure static and dynamic properties of cavity-embedded materials. Copyright © 2024, The Authors. All rights reserved.

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NISQ-friendly measurement-based quantum clustering algorithms

arXiv

引用

arXiv 2023年

作者： Patil, Srushti Banerjee, Shreya Panigrahi, Prasanta K. NNF Quantum Computing Programme Neils Bphr Institute University of Copenhagen Copenhagen NDK-2200 Denmark Department of Physics Indian Institute of Science Education and Research Andhra Pradesh Tirupati517619 India Center for Quantum Science and Technology Siksha'O' Anusandhan University Bhubaneswar Odisha 751030 India Institut Quantique Université de Sherbrooke QCJ1K2R1 Canada Department of Physical Sciences Indian Institute of Science Education and Research West Bengal Kolkata741246 India

Two novel measurement-based, quantum clustering algorithms are proposed basedon quantum parallelism and entanglement. The first algorithm follows a divisiveapproach. The second algorithm is based on unsharp measurements, where weconstruct an effect operator with a Gaussian probability distribution tocluster similar data points. A major advantage of both algorithms is that theyare simplistic in nature, easy to implement, and well suited for noisyintermediate scale quantum computers. We have successfully applied the firstalgorithm on a concentric circle data set, where the classical clusteringapproach fails, as well as on the Churrtiz data set of $130$ cities, where weshow that the algorithm succeeds with very low quantum resources. We appliedthe second algorithm on the labeled Wisconsin breast cancer dataset, and foundthat it is able to classify the dataset with high accuracy using only$O(log(D))$ qubits and polynomial measurements, where $D$ is the maximaldistance within any two points in the dataset. We also show that this algorithmworks better with an assumed measurement error in the quantum system, making itextremely well-suited for NISQ devices. © 2023, CC BY.

关键词： Clustering algorithms

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Epitaxially Driven Phase Selectivity of Sn in Hybrid quantum Nanowires

arXiv

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arXiv 2022年

作者： Khan, Sabbir A. Martí-Sánchez, Sara Olsteins, Dags Lampadaris, Charalampos Carrad, Damon James Liu, Yu Quiñones, Judith Spadaro, Maria Chiara Jespersen, Thomas S. Krogstrup, Peter Arbiol, Jordi Center for Quantum Devices Niels Bohr Institute University of Copenhagen Copenhagen2100 Denmark Danish Fundamental Metrology Kogle Alle 5 Hørsholm2970 Denmark CSIC and BIST Campus UAB Bellaterra Catalonia Barcelona08193 Spain Department of Energy Conversion and Storage Technical University of Denmark Fysikvej Building 310 Lyngby2800 Denmark NNF Quantum Computing Programme Niels Bohr Institute University of Copenhagen Denmark ICREA Pg. Lluís Companys 23 Catalonia Barcelona08010 Spain

Hybrid semiconductor/superconductor nanowires constitute a pervasive platform for studying gate-tunable superconductivity and the emergence of topological behavior. Their low-dimensionality and crystal structure flexibility facilitate novel heterostructure growth and efficient material optimization;crucial prerequisites for accurately constructing complex multi-component quantum materials. Here, we present an extensive optimization of Sn growth on InSb, InAsSb and InAs nanowires. We demonstrate how the growth conditions and the crystal structure/symmetry of the semiconductor drive the formation of either semi-metallic α − Sn or superconducting β − Sn. For InAs nanowires, we obtain phase-pure, superconducting β − Sn shells. However, for InSb and InAsSb nanowires, an initial epitaxial α − Sn phase evolves into a polycrystalline shell of coexisting α and β phases, where the β/α volume ratio increases with Sn shell thickness. Whether these nanowires exhibit superconductivity or not critically relies on the β − Sn content. Therefore, this work provides key insights into Sn phase control on a variety of semiconductors, with consequences for the yield of superconducting hybrids suitable for generating topological systems. © 2022, CC BY-NC-ND.

关键词： Nanowires

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