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Realistic simulation of quantum computation using unitary and measurement channels

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Physical Review A 2020年第5期102卷 052608-052608页

作者： Ahmed Abid Moueddene Nader Khammassi Koen Bertels Carmen G. Almudever QuTech Delft University of Technology Delft Netherlands Intel Labs Intel Corporation Hillsboro 97124 OR United States Quantum Computer Engineering Department Delft University of Technology Delft Netherlands

The implementation and practicality of quantum algorithms hinge largely on the quality of operations within a quantum processor. Therefore, including realistic error models in quantum computing simulation platforms is crucial for testing these algorithms. Existing classical simulation techniques of quantum information processing devices exhibit a tradeoff between scalability (the number of qubits that can be simulated) and accuracy (how close the simulation is to the target error model). In this paper, we introduce a simulation approach that relies on approximating the density matrix evolution with a stochastic sum of unitary and measurement channels within a pure-state simulation environment. This model shows an improvement of at least one order of magnitude in terms of accuracy compared to the best known stochastic approaches while allowing us to simulate a larger number of qubits compared to the exact density matrix simulation. Furthermore, we used this approach to realistically simulate Grover's algorithm and the surface code 17 using a gate set tomography characterization of quantum operations as a noise model.

关键词： quantum algorithms quantum benchmarking quantum channels quantum error correction quantum gates quantum tomography Surface code quantum computing Topological quantum computing

Triplet correlations in Cooper pair splitters realized in a two-dimensional electron gas

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arXiv 2022年

作者： Wang, Qingzhen Haaf, Sebastiaan ten L.D. Kulesh, Ivan Xiao, Di Thomas, Candice Manfra, Michael J. Goswami, Srijit QuTech and Kavli Institute of Nanoscience Delft University of Technology Delft2600 GA Netherlands Department of Physics and Astronomy Purdue University West LafayetteIN47907 United States Elmore School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States School of Materials Engineering Purdue University West LafayetteIN47907 United States Microsoft Quantum Lab West LafayetteIN47907 United States

Cooper pairs occupy the ground state of superconductors and are typically composed of maximally entangled electrons with opposite spin. In order to study the spin and entanglement properties of these electrons, one must separate them spatially via a process known as Cooper pair splitting (CPS). Here we provide the first demonstration of CPS in a semiconductor two-dimensional electron gas (2DEG). By coupling two quantum dots to a superconductor-semiconductor hybrid region we achieve efficient Cooper pair splitting, and clearly distinguish it from other local and non-local processes. When the spin degeneracy of the dots is lifted, they can be operated as spin-filters to obtain information about the spin of the electrons forming the Cooper pair. Not only do we observe a near perfect splitting of Cooper pairs into opposite-spin electrons (i.e. conventional singlet pairing), but also into equal-spin electrons, thus achieving triplet correlations between the quantum dots. Importantly, the exceptionally large spin-orbit interaction in our 2DEGs results in a strong triplet component, comparable in amplitude to the singlet pairing. The demonstration of CPS in a scalable and flexible platform provides a credible route to study on-chip entanglement and topological superconductivity in the form of artificial Kitaev chains. © 2022, CC BY.

关键词： Electrons

Realizing quantum Algorithms on Real quantum Computing Devices

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arXiv 2020年

作者： Almudever, Carmen G. Lao, Lingling Wille, Robert Guerreschi, Gian Giacomo Quantum & Computer Engineering Department and QuTech Delft University of Technology Institute for Integrated Circuits Johannes Kepler University Linz Intel Labs

quantum computing is currently moving from an academic idea to a practical reality. quantum computing in the cloud is already available and allows users from all over the world to develop and execute real quantum algorithms. However, companies which are heavily investing in this new technology such as Google, IBM, Rigetti, Intel, IonQ, and Xanadu follow diverse technological approaches. This led to a situation where we have substantially different quantum computing devices available thus far. They mostly differ in the number and kind of qubits and the connectivity between them. Because of that, various methods for realizing the intended quantum functionality on a given quantum computing device are available. This paper provides an introduction and overview into this domain and describes corresponding methods, also referred to as compilers, mappers, synthesizers, transpilers, or routers. Copyright © 2020, The Authors. All rights reserved.

关键词： Qubits

Limitations of nearest-neighbour quantum networks

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arXiv 2022年

作者： Hahn, Frederik Dahlberg, Axel Eisert, Jens Pappa, Anna Dahlem Center for Complex Quantum Systems Freie Universität Berlin Berlin14195 Germany Electrical Engineering and Computer Science Department Technische Universität Berlin Berlin10587 Germany QuTech TU Delft Delft2628CJ Netherlands Fraunhofer Heinrich Hertz Institute Berlin10587 Germany Fraunhofer Institute for Open Communication Systems - FOKUS Berlin10589 Germany

quantum communication research has in recent years shifted to include multi-partite networks for which questions of quantum network routing naturally emerge. To understand the potential for multi-partite routing, we focus on the most promising architectures for future quantum networks - those connecting nodes close to each other. Nearest-neighbour networks such as rings, lines, and grids, have been studied under different communication scenarios to facilitate the sharing of quantum resources, especially in the presence of bottlenecks. We here analyze the potential of nearest-neighbour quantum networks and identify some serious limitations, by demonstrating that rings and lines cannot overcome common bottleneck communication problems. © 2022, CC BY.

关键词： quantum communication

Spiderweb Array: A Sparse Spin-Qubit Array

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Physical Review Applied 2022年第2期18卷 024053-024053页

作者： Jelmer M. Boter Juan P. Dehollain Jeroen P.G. van Dijk Yuanxing Xu Toivo Hensgens Richard Versluis Henricus W.L. Naus James S. Clarke Menno Veldhorst Fabio Sebastiano Lieven M.K. Vandersypen QuTech Delft University of Technology Lorentzweg 1 Delft 2628 CJ Netherlands Kavli Institute of Nanoscience Delft University of Technology Lorentzweg 1 Delft 2628 CJ Netherlands School of Mathematical and Physical Sciences University of Technology Sydney Ultimo NSW 2007 Australia Department of Quantum and Computer Engineering Delft University of Technology Delft 2628 CJ Netherlands Netherlands Organization for Applied Scientific Research (TNO) P.O. Box 155 Delft 2600 AD Netherlands Components Research Intel Corporation 2501 NE Century Blvd Hillsboro Oregon 97124 USA

One of the main bottlenecks in the pursuit of a large-scale–chip-based quantum computer is the large number of control signals needed to operate qubit systems. As system sizes scale up, the number of terminals required to connect to off-chip control electronics quickly becomes unmanageable. Here, we discuss a quantum-dot spin-qubit architecture that integrates on-chip control electronics, allowing for a significant reduction in the number of signal connections at the chip boundary. By arranging the qubits in a two-dimensional array with about 12μm pitch, we create space to implement locally integrated sample-and-hold circuits. This allows us to offset the inhomogeneities in the potential landscape across the array and to globally share the majority of the control signals for qubit operations. We make use of advanced circuit modeling software to go beyond conceptual drawings of the component layout, to assess the feasibility of the scheme through a concrete floor plan, including estimates of footprints for quantum and classical electronics, as well as routing of signal lines across the chip using different interconnect layers. We make use of local demultiplexing circuits to achieve an efficient signal-connection scaling, leading to a Rent’s exponent as low as p=0.43. Furthermore, we use available data from state-of-the-art spin qubit and microelectronics technology development, as well as circuit models and simulations, to estimate the operation frequencies and power consumption of a million-qubit array. This work presents a complementary approach to previously proposed architectures, focusing on a feasible scheme to integrating quantum and classical hardware, and identifying remaining challenges for achieving full fault-tolerant quantum computation. It thereby significantly closes the gap towards a fully CMOS-compatible quantum computer implementation.

关键词： quantum information with solid state qubits Radio frequency techniques Spin blockade Demultiplexers Devices Elemental semiconductors quantum dots Electron spin resonance

Single-photon detectors on arbitrary photonic substrates

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arXiv 2024年

作者： Tao, Max Larocque, Hugo Gyger, Samuel Colangelo, Marco Medeiros, Owen Christen, Ian Sattari, Hamed Choong, Gregory Petremand, Yves Prieto, Ivan Yu, Yang Steinhauer, Stephan Leake, Gerald L. Coleman, Daniel J. Ghadimi, Amir H. Fanto, Michael L. Zwiller, Val Englund, Dirk Errando-Herranz, Carlos Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States KTH Royal Institute of Technology Stockholm Sweden Centre Suisse d’Electronique et de Microtechnique Neuchatel Switzerland Raith America Inc. TroyNY United States State University of New York Polytechnic Institute AlbanyNY12203 United States Air Force Research Laboratory Information Directorate RomeNY13441 United States Institute of Physics University of Münster Münster48149 Germany Department of Quantum and Computer Engineering Delft University of Technology Delft Netherlands QuTech Delft University of Technology Delft Netherlands

Detecting non-classical light is a central requirement for photonics-based quantum technologies. Unrivaled high efficiencies and low dark counts have positioned superconducting nanowire single photon detectors (SNSPDs) as the leading detector technology for fiber and integrated photonic applications. However, a central challenge lies in their integration within photonic integrated circuits regardless of material platform or surface topography. Here, we introduce a method based on transfer printing that overcomes these constraints and allows for the integration of SNSPDs onto arbitrary photonic substrates. We prove this by integrating SNSPDs and showing through-waveguide single-photon detection in commercially manufactured silicon and lithium niobate on insulator integrated photonic circuits. Our method eliminates bottlenecks to the integration of high-quality single-photon detectors, turning them into a versatile and accessible building block for scalable quantum information processing. © 2024, CC BY.

关键词： Particle beams

Controlling Andreev bound states with the magnetic vector potential

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arXiv 2022年

作者： Moehle, Christian M. Rout, Prasanna K. Jainandunsing, Nayan A. Kuiri, Dibyendu Ke, Chung Ting Xiao, Di Thomas, Candice Manfra, Michael J. Nowak, Michal P. Goswami, Srijit QuTech Kavli Institute of Nanoscience Delft University of Technology Delft2600 GA Netherlands Agh University of Science and Technology Academic Centre for Materials and Nanotechnology Krakow30-059 Poland Department of Physics and Astronomy Purdue University West LafayetteIN47907 United States Elmore School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States School of Materials Engineering Purdue University West LafayetteIN47907 United States Microsoft Quantum Lab West Lafayette West LafayetteIN47907 United States

Tunneling spectroscopy measurements are often used to probe the energy spectrum of Andreev bound states (ABSs) in semiconductor-superconductor hybrids. Recently, this spectroscopy technique has been incorporated into planar Josephson junctions (JJs) formed in two-dimensional electron gases, a potential platform to engineer phase-controlled topological superconductivity. Here, we perform ABS spectroscopy at the two ends of planar JJs and study the effects of the magnetic vector potential on the ABS spectrum. We show that the local superconducting phase difference arising from the vector potential is equal in magnitude and opposite in sign at the two ends, in agreement with a model that assumes localized ABSs near the tunnel barriers. Complemented with microscopic simulations, our experiments demonstrate that the local phase difference can be used to estimate the relative position of localized ABSs separated by a few hundred nanometers. © 2022, CC BY.

关键词： Scanning tunneling microscopy

Resource-efficient fault-tolerant one-way quantum repeater with code concatenation

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arXiv 2023年

作者： Wo, Kah Jen Avis, Guus Rozpędek, Filip Mor-Ruiz, Maria Flors Pieplow, Gregor Schröder, Tim Jiang, Liang Sørensen, Anders S. Borregaard, Johannes QuTech Delft University of Technology Lorentzweg 1 Delft2628 CJ Netherlands Quantum Technologies National University of Singapore Queenstown117543 Singapore Quantum Computer Science EEMCS Delft University of Technology Lorentzweg 1 Delft2628 CJ Netherlands Kavli Institute of Nanoscience Delft University of Technology Lorentzweg 1 Delft2628 CJ Netherlands Pritzker School of Molecular Engineering University of Chicago ChicagoIL60637 United States College of Information and Computer Sciences University of Massachusetts Amherst AmherstMA01003 United States Universität Innsbruck Institut für Theoretische Physik Technikerstraße 21a Innsbruck6020 Austria Department of Physics Humboldt-Universität zu Berlin Newtonstraße 15 Berlin12489 Germany The Niels Bohr Institute University of Copenhagen Blegdamsvej 17 Copenhagen ØDK-2100 Denmark

One-way quantum repeaters where loss and operational errors are counteracted by quantum error correcting codes can ensure fast and reliable qubit transmission in quantum networks. It is crucial that the resource requirements of such repeaters, for example, the number of qubits per repeater node and the complexity of the quantum error correcting operations are kept to a minimum to allow for near-future implementations. To this end, we propose a one-way quantum repeater that targets both the loss and operational error rates in a communication channel in a resource-efficient manner using code concatenation. Specifically, we consider a tree-cluster code as an inner loss-tolerant code concatenated with an outer 5-qubit code for protection against Pauli errors. Adopting flag-based stabilizer measurements, we show that intercontinental distances of up to 10,000 km can be bridged with a minimized resource overhead by interspersing repeater nodes that each specializes in suppressing either loss or operational errors. Our work demonstrates how tailored error-correcting codes can significantly lower the experimental requirements for long-distance quantum communication. © 2023, CC BY.

关键词： Concatenated codes

quantum repeaters: From quantum networks to the quantum internet

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arXiv 2022年

作者： Azuma, Koji Economou, Sophia E. Elkouss, David Hilaire, Paul Jiang, Liang Lo, Hoi-Kwong Tzitrin, Ilan NTT Basic Research Laboratories NTT Corporation 3-1 Morinosato Wakamiya Kanagawa Atsugi243-0198 Japan NTT Research Center for Theoretical Quantum Physics NTT Corporation 3-1 Morinosato-Wakamiya Kanagawa Atsugi243-0198 Japan Department of Physics Virginia Tech BlacksburgVA24061 United States QuTech Delft University of Technology Lorentzweg 1 Delft2628 CJ Netherlands Networked Quantum Devices Unit Okinawa Institute of Science and Technology Graduate University Okinawa Japan Quandela SAS 10 Boulevard Thomas Gobert Palaiseau91120 France Pritzker School of Molecular Engineering The University of Chicago ChicagoIL60637 United States Quantum Bridge Technologies Inc. 100 College Street TorontoONM5G 1L5 Canada Department of Physics University of Hong Kong Pokfulam Hong Kong Center for Quantum Information and Quantum Control Department of Physics Department of Electrical & Computer Engineering University of Toronto TorontoM5S 3G4 Canada Department of Physics University of Toronto Toronto Canada

A quantum internet is the holy grail of quantum information processing, enabling the deployment of a broad range of quantum technologies and protocols on a global scale. However, numerous challenges exist before the quantum internet can become a reality. Perhaps the most crucial of these is the realization of a quantum repeater, an essential component in the long-distance transmission of quantum information. As the analog of a classical repeater, extender, or booster, the quantum repeater works to overcome loss and noise in the quantum channels comprising a quantum network. Here, we review the conceptual frameworks and architectures for quantum repeaters, as well as the experimental progress towards their realization. We also discuss the various near-term proposals to overcome the limits to the communication rates set by point-to-point quantum communication. Finally, we overview how quantum repeaters fit within the broader challenge of designing and implementing a quantum internet. Copyright © 2022, The Authors. All rights reserved.

关键词： quantum optics