1
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Gupta RS, Sundaresan N, Alexander T, Wood CJ, Merkel ST, Healy MB, Hillenbrand M, Jochym-O'Connor T, Wootton JR, Yoder TJ, Cross AW, Takita M, Brown BJ. Encoding a magic state with beyond break-even fidelity. Nature 2024; 625:259-263. [PMID: 38200302 PMCID: PMC10781628 DOI: 10.1038/s41586-023-06846-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 11/07/2023] [Indexed: 01/12/2024]
Abstract
To run large-scale algorithms on a quantum computer, error-correcting codes must be able to perform a fundamental set of operations, called logic gates, while isolating the encoded information from noise1-8. We can complete a universal set of logic gates by producing special resources called magic states9-11. It is therefore important to produce high-fidelity magic states to conduct algorithms while introducing a minimal amount of noise to the computation. Here we propose and implement a scheme to prepare a magic state on a superconducting qubit array using error correction. We find that our scheme produces better magic states than those that can be prepared using the individual qubits of the device. This demonstrates a fundamental principle of fault-tolerant quantum computing12, namely, that we can use error correction to improve the quality of logic gates with noisy qubits. Moreover, we show that the yield of magic states can be increased using adaptive circuits, in which the circuit elements are changed depending on the outcome of mid-circuit measurements. This demonstrates an essential capability needed for many error-correction subroutines. We believe that our prototype will be invaluable in the future as it can reduce the number of physical qubits needed to produce high-fidelity magic states in large-scale quantum-computing architectures.
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Affiliation(s)
- Riddhi S Gupta
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
- IBM Quantum, Almaden Research Center, San Jose, CA, USA
| | | | - Thomas Alexander
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | | | - Seth T Merkel
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | - Michael B Healy
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | | | - Tomas Jochym-O'Connor
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
- IBM Quantum, Almaden Research Center, San Jose, CA, USA
| | | | - Theodore J Yoder
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | - Andrew W Cross
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | - Maika Takita
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA
| | - Benjamin J Brown
- IBM Quantum, T. J. Watson Research Center, Yorktown Heights, NY, USA.
- IBM Denmark, Brøndby, Denmark.
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2
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Reuer K, Landgraf J, Fösel T, O'Sullivan J, Beltrán L, Akin A, Norris GJ, Remm A, Kerschbaum M, Besse JC, Marquardt F, Wallraff A, Eichler C. Realizing a deep reinforcement learning agent for real-time quantum feedback. Nat Commun 2023; 14:7138. [PMID: 37932251 PMCID: PMC10628214 DOI: 10.1038/s41467-023-42901-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 10/25/2023] [Indexed: 11/08/2023] Open
Abstract
Realizing the full potential of quantum technologies requires precise real-time control on time scales much shorter than the coherence time. Model-free reinforcement learning promises to discover efficient feedback strategies from scratch without relying on a description of the quantum system. However, developing and training a reinforcement learning agent able to operate in real-time using feedback has been an open challenge. Here, we have implemented such an agent for a single qubit as a sub-microsecond-latency neural network on a field-programmable gate array (FPGA). We demonstrate its use to efficiently initialize a superconducting qubit and train the agent based solely on measurements. Our work is a first step towards adoption of reinforcement learning for the control of quantum devices and more generally any physical device requiring low-latency feedback.
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Affiliation(s)
- Kevin Reuer
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland.
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland.
| | - Jonas Landgraf
- Max Planck Institute for the Science of Light, Staudtstraße 2, 91058, Erlangen, Germany
- Physics Department, University of Erlangen-Nuremberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Thomas Fösel
- Max Planck Institute for the Science of Light, Staudtstraße 2, 91058, Erlangen, Germany
- Physics Department, University of Erlangen-Nuremberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - James O'Sullivan
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Liberto Beltrán
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Abdulkadir Akin
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Graham J Norris
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Ants Remm
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Michael Kerschbaum
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Jean-Claude Besse
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Florian Marquardt
- Max Planck Institute for the Science of Light, Staudtstraße 2, 91058, Erlangen, Germany
- Physics Department, University of Erlangen-Nuremberg, Staudtstraße 5, 91058, Erlangen, Germany
| | - Andreas Wallraff
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland
- Quantum Center, ETH Zurich, CH-8093, Zurich, Switzerland
| | - Christopher Eichler
- Department of Physics, ETH Zurich, CH-8093, Zurich, Switzerland.
- Physics Department, University of Erlangen-Nuremberg, Staudtstraße 5, 91058, Erlangen, Germany.
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3
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Antoniadis NO, Hogg MR, Stehl WF, Javadi A, Tomm N, Schott R, Valentin SR, Wieck AD, Ludwig A, Warburton RJ. Cavity-enhanced single-shot readout of a quantum dot spin within 3 nanoseconds. Nat Commun 2023; 14:3977. [PMID: 37407552 DOI: 10.1038/s41467-023-39568-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 06/14/2023] [Indexed: 07/07/2023] Open
Abstract
Rapid, high-fidelity single-shot readout of quantum states is a ubiquitous requirement in quantum information technologies. For emitters with a spin-preserving optical transition, spin readout can be achieved by driving the transition with a laser and detecting the emitted photons. The speed and fidelity of this approach is typically limited by low photon collection rates and measurement back-action. Here we use an open microcavity to enhance the optical readout signal from a semiconductor quantum dot spin state, largely overcoming these limitations. We achieve single-shot readout of an electron spin in only 3 nanoseconds with a fidelity of (95.2 ± 0.7)%, and observe quantum jumps using repeated single-shot measurements. Owing to the speed of our readout, errors resulting from measurement-induced back-action have minimal impact. Our work reduces the spin readout-time well below both the achievable spin relaxation and dephasing times in semiconductor quantum dots, opening up new possibilities for their use in quantum technologies.
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Affiliation(s)
- Nadia O Antoniadis
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - Mark R Hogg
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland.
| | - Willy F Stehl
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - Alisa Javadi
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
- School of Electrical and Computer Engineering, Department of Physics and Astronomy, The University of Oklahoma, 110 West Boyd Street, Norman, OK, 73019, USA
| | - Natasha Tomm
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - Rüdiger Schott
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780, Bochum, Germany
| | - Sascha R Valentin
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780, Bochum, Germany
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780, Bochum, Germany
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780, Bochum, Germany
| | - Richard J Warburton
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland.
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4
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Zhang X, Kim E, Mark DK, Choi S, Painter O. A superconducting quantum simulator based on a photonic-bandgap metamaterial. Science 2023; 379:278-283. [PMID: 36656924 DOI: 10.1126/science.ade7651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Synthesizing many-body quantum systems with various ranges of interactions facilitates the study of quantum chaotic dynamics. Such extended interaction range can be enabled by using nonlocal degrees of freedom such as photonic modes in an otherwise locally connected structure. Here, we present a superconducting quantum simulator in which qubits are connected through an extensible photonic-bandgap metamaterial, thus realizing a one-dimensional Bose-Hubbard model with tunable hopping range and on-site interaction. Using individual site control and readout, we characterize the statistics of measurement outcomes from many-body quench dynamics, which enables in situ Hamiltonian learning. Further, the outcome statistics reveal the effect of increased hopping range, showing the predicted crossover from integrability to ergodicity. Our work enables the study of emergent randomness from chaotic many-body evolution and, more broadly, expands the accessible Hamiltonians for quantum simulation using superconducting circuits.
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Affiliation(s)
- Xueyue Zhang
- Thomas J. Watson, Sr., Laboratory of Applied Physics and Kavli Nanoscience Institute, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA 91125, USA
| | - Eunjong Kim
- Thomas J. Watson, Sr., Laboratory of Applied Physics and Kavli Nanoscience Institute, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA 91125, USA
| | - Daniel K Mark
- Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Soonwon Choi
- Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Oskar Painter
- Thomas J. Watson, Sr., Laboratory of Applied Physics and Kavli Nanoscience Institute, California Institute of Technology, Pasadena, CA 91125, USA.,Institute for Quantum Information and Matter, California Institute of Technology, Pasadena, CA 91125, USA.,AWS Center for Quantum Computing, Pasadena, CA 91125, USA
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5
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Buffoni L, Gherardini S, Zambrini Cruzeiro E, Omar Y. Third Law of Thermodynamics and the Scaling of Quantum Computers. PHYSICAL REVIEW LETTERS 2022; 129:150602. [PMID: 36269957 DOI: 10.1103/physrevlett.129.150602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 06/16/2023]
Abstract
The third law of thermodynamics, also known as the Nernst unattainability principle, puts a fundamental bound on how close a system, whether classical or quantum, can be cooled to a temperature near to absolute zero. On the other hand, a fundamental assumption of quantum computing is to start each computation from a register of qubits initialized in a pure state, i.e., at zero temperature. These conflicting aspects, at the interface between quantum computing and thermodynamics, are often overlooked or, at best, addressed only at a single-qubit level. In this Letter, we argue how the existence of a small but finite effective temperature, which makes the initial state a mixed state, poses a real challenge to the fidelity constraints required for the scaling of quantum computers. Our theoretical results, carried out for a generic quantum circuit with N-qubit input states, are validated by test runs performed on a real quantum processor.
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Affiliation(s)
| | - Stefano Gherardini
- PQI-Portuguese Quantum Institute, 1049-001 Lisboa, Portugal
- CNR-INO, Area Science Park, Basovizza, I-34149 Trieste, Italy
- LENS, University of Florence, via G. Sansone 1, I-50019 Sesto Fiorentino, Italy
| | | | - Yasser Omar
- PQI-Portuguese Quantum Institute, 1049-001 Lisboa, Portugal
- Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Centro de Física e Engenharia de Materiais Avançados (CeFEMA), Physics of Information and Quantum Technologies Group, 1049-001 Lisboa, Portugal
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6
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Tholén MO, Borgani R, Di Carlo GR, Bengtsson A, Križan C, Kudra M, Tancredi G, Bylander J, Delsing P, Gasparinetti S, Haviland DB. Measurement and control of a superconducting quantum processor with a fully integrated radio-frequency system on a chip. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:104711. [PMID: 36319392 DOI: 10.1063/5.0101398] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
We describe a digital microwave platform called Presto, designed for measurement and control of multiple quantum bits (qubits) and based on the third-generation radio-frequency system on a chip. Presto uses direct digital synthesis to create signals up to 9 GHz on 16 synchronous output ports, while synchronously analyzing responses on 16 input ports. Presto has 16 DC-bias outputs, four inputs and four outputs for digital triggers or markers, and two continuous-wave outputs for synthesizing frequencies up to 15 GHz. Scaling to a large number of qubits is enabled through deterministic synchronization of multiple Presto units. A Python application programming interface configures a firmware for synthesis and analysis of pulses, coordinated by an event sequencer. The analysis integrates template matching (matched filtering) and low-latency (184-254 ns) feedback to enable a wide range of multi-qubit experiments. We demonstrate Presto's capabilities with experiments on a sample consisting of two superconducting qubits connected via a flux-tunable coupler. We show single-shot readout and active reset of a single qubit; randomized benchmarking of single-qubit gates showing 99.972% fidelity, limited by the coherence time of the qubit; and calibration of a two-qubit iSWAP gate.
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Affiliation(s)
- Mats O Tholén
- Nanostructure Physics, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden
| | - Riccardo Borgani
- Nanostructure Physics, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden
| | | | - Andreas Bengtsson
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Christian Križan
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Marina Kudra
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Giovanna Tancredi
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Jonas Bylander
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Per Delsing
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Simone Gasparinetti
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - David B Haviland
- Nanostructure Physics, KTH Royal Institute of Technology, 106 91 Stockholm, Sweden
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7
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Deliyannis P, Sud J, Chamaki D, Webb-Mack Z, Bauer CW, Nachman B. Improving quantum simulation efficiency of final state radiation with dynamic quantum circuits. Int J Clin Exp Med 2022. [DOI: 10.1103/physrevd.106.036007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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8
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Annby-Andersson B, Bakhshinezhad F, Bhattacharyya D, De Sousa G, Jarzynski C, Samuelsson P, Potts PP. Quantum Fokker-Planck Master Equation for Continuous Feedback Control. PHYSICAL REVIEW LETTERS 2022; 129:050401. [PMID: 35960579 DOI: 10.1103/physrevlett.129.050401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 06/24/2022] [Indexed: 06/15/2023]
Abstract
Measurement and feedback control are essential features of quantum science, with applications ranging from quantum technology protocols to information-to-work conversion in quantum thermodynamics. Theoretical descriptions of feedback control are typically given in terms of stochastic equations requiring numerical solutions, or are limited to linear feedback protocols. Here we present a formalism for continuous quantum measurement and feedback, both linear and nonlinear. Our main result is a quantum Fokker-Planck master equation describing the joint dynamics of a quantum system and a detector with finite bandwidth. For fast measurements, we derive a Markovian master equation for the system alone, amenable to analytical treatment. We illustrate our formalism by investigating two basic information engines, one quantum and one classical.
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Affiliation(s)
| | - Faraj Bakhshinezhad
- Physics Department and NanoLund, Lund University, Box 118, 22100 Lund, Sweden
| | - Debankur Bhattacharyya
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
| | - Guilherme De Sousa
- Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Christopher Jarzynski
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
| | - Peter Samuelsson
- Physics Department and NanoLund, Lund University, Box 118, 22100 Lund, Sweden
| | - Patrick P Potts
- Physics Department and NanoLund, Lund University, Box 118, 22100 Lund, Sweden
- Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
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9
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Trade off-free entanglement stabilization in a superconducting qutrit-qubit system. Nat Commun 2022; 13:3994. [PMID: 35810169 PMCID: PMC9271051 DOI: 10.1038/s41467-022-31638-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 06/28/2022] [Indexed: 11/09/2022] Open
Abstract
Quantum reservoir engineering is a powerful framework for autonomous quantum state preparation and error correction. However, traditional approaches to reservoir engineering are hindered by unavoidable coherent leakage out of the target state, which imposes an inherent trade off between achievable steady-state state fidelity and stabilization rate. In this work we demonstrate a protocol that achieves trade off-free Bell state stabilization in a qutrit-qubit system realized on a circuit-QED platform. We accomplish this by creating a purely dissipative channel for population transfer into the target state, mediated by strong parametric interactions coupling the second-excited state of a superconducting transmon and the engineered bath resonator. Our scheme achieves a state preparation fidelity of 84% with a stabilization time constant of 339 ns, leading to a 54 ns error-time product in a solid-state quantum information platform.
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10
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Zhou Y, Zhang Z, Yin Z, Huai S, Gu X, Xu X, Allcock J, Liu F, Xi G, Yu Q, Zhang H, Zhang M, Li H, Song X, Wang Z, Zheng D, An S, Zheng Y, Zhang S. Rapid and unconditional parametric reset protocol for tunable superconducting qubits. Nat Commun 2021; 12:5924. [PMID: 34635663 PMCID: PMC8505451 DOI: 10.1038/s41467-021-26205-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 09/13/2021] [Indexed: 11/09/2022] Open
Abstract
Qubit initialization is a critical task in quantum computation and communication. Extensive efforts have been made to achieve this with high speed, efficiency and scalability. However, previous approaches have either been measurement-based and required fast feedback, suffered from crosstalk or required sophisticated calibration. Here, we report a fast and high-fidelity reset scheme, avoiding the issues above without any additional chip architecture. By modulating the flux through a transmon qubit, we realize a swap between the qubit and its readout resonator that suppresses the excited state population to 0.08% ± 0.08% within 34 ns (284 ns if photon depletion of the resonator is required). Furthermore, our approach (i) can achieve effective second excited state depletion, (ii) has negligible effects on neighboring qubits, and (iii) offers a way to entangle the qubit with an itinerant single photon, useful in quantum communication applications.
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Affiliation(s)
- Yu Zhou
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Zhenxing Zhang
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Zelong Yin
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Sainan Huai
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Xiu Gu
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Xiong Xu
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Jonathan Allcock
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Fuming Liu
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Guanglei Xi
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Qiaonian Yu
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Hualiang Zhang
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Mengyu Zhang
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Hekang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaohui Song
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhan Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Dongning Zheng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shuoming An
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China.
| | - Yarui Zheng
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
| | - Shengyu Zhang
- Tencent Quantum Laboratory, Tencent, Shenzhen, Guangdong, 518057, China
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11
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Córcoles AD, Takita M, Inoue K, Lekuch S, Minev ZK, Chow JM, Gambetta JM. Exploiting Dynamic Quantum Circuits in a Quantum Algorithm with Superconducting Qubits. PHYSICAL REVIEW LETTERS 2021; 127:100501. [PMID: 34533358 DOI: 10.1103/physrevlett.127.100501] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 08/06/2021] [Indexed: 06/13/2023]
Abstract
To date, quantum computation on real, physical devices has largely been limited to simple, time-ordered sequences of unitary operations followed by a final projective measurement. As hardware platforms for quantum computing continue to mature in size and capability, it is imperative to enable quantum circuits beyond their conventional construction. Here we break into the realm of dynamic quantum circuits on a superconducting-based quantum system. Dynamic quantum circuits not only involve the evolution of the quantum state throughout the computation but also periodic measurements of qubits midcircuit and concurrent processing of the resulting classical information on timescales shorter than the execution times of the circuits. Using noisy quantum hardware, we explore one of the most fundamental quantum algorithms, quantum phase estimation, in its adaptive version, which exploits dynamic circuits, and compare the results to a nonadaptive implementation of the same algorithm. We demonstrate that the version of real-time quantum computing with dynamic circuits can yield results comparable to an approach involving classical asynchronous postprocessing, thus opening the door to a new realm of available algorithms on real quantum systems.
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Affiliation(s)
- A D Córcoles
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Maika Takita
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Ken Inoue
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Scott Lekuch
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Zlatko K Minev
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Jerry M Chow
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
| | - Jay M Gambetta
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, USA
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12
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Peronnin T, Marković D, Ficheux Q, Huard B. Sequential Dispersive Measurement of a Superconducting Qubit. PHYSICAL REVIEW LETTERS 2020; 124:180502. [PMID: 32441960 DOI: 10.1103/physrevlett.124.180502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
We present a superconducting device that realizes the sequential measurement of a transmon qubit. The device disables common limitations of dispersive readout such as Purcell effect or transients in the cavity mode by turning on and off the coupling to the measurement channel on demand. The qubit measurement begins by loading a readout resonator that is coupled to the qubit. After an optimal interaction time with negligible loss, a microwave pump releases the content of the readout mode by upconversion into a measurement line in a characteristic time as low as 10 ns, which is 400 times shorter than the lifetime of the readout resonator. A direct measurement of the released field quadratures demonstrates a readout fidelity of 97.5% in a total measurement time of 220 ns. The Wigner tomography of the readout mode allows us to characterize the non-Gaussian nature of the readout mode and its dynamics.
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Affiliation(s)
- T Peronnin
- Université Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, F-69342 Lyon, France
| | - D Marković
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Sud, Université Paris-Saclay, 91767 Palaiseau, France
| | - Q Ficheux
- Université Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, F-69342 Lyon, France
| | - B Huard
- Université Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire de Physique, F-69342 Lyon, France
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13
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Naghiloo M, Tan D, Harrington PM, Alonso JJ, Lutz E, Romito A, Murch KW. Heat and Work Along Individual Trajectories of a Quantum Bit. PHYSICAL REVIEW LETTERS 2020; 124:110604. [PMID: 32242716 DOI: 10.1103/physrevlett.124.110604] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Accepted: 02/07/2020] [Indexed: 06/11/2023]
Abstract
We use a near quantum limited detector to experimentally track individual quantum state trajectories of a driven qubit formed by the hybridization of a waveguide cavity and a transmon circuit. For each measured quantum coherent trajectory, we separately identify energy changes of the qubit as heat and work, and verify the first law of thermodynamics for an open quantum system. We further establish the consistency of these results by comparison with the master equation approach and the two-projective-measurement scheme, both for open and closed dynamics, with the help of a quantum feedback loop that compensates for the exchanged heat and effectively isolates the qubit.
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Affiliation(s)
- M Naghiloo
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - D Tan
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - P M Harrington
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - J J Alonso
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - E Lutz
- Institute for Theoretical Physics I, University of Stuttgart, D-70550 Stuttgart, Germany
| | - A Romito
- Department of Physics, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - K W Murch
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
- Institute for Materials Science and Engineering, St. Louis, Missouri 63130, USA
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14
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To catch and reverse a quantum jump mid-flight. Nature 2019; 570:200-204. [DOI: 10.1038/s41586-019-1287-z] [Citation(s) in RCA: 132] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/04/2019] [Indexed: 11/08/2022]
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15
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Nakajima T, Noiri A, Yoneda J, Delbecq MR, Stano P, Otsuka T, Takeda K, Amaha S, Allison G, Kawasaki K, Ludwig A, Wieck AD, Loss D, Tarucha S. Quantum non-demolition measurement of an electron spin qubit. NATURE NANOTECHNOLOGY 2019; 14:555-560. [PMID: 30988474 DOI: 10.1038/s41565-019-0426-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 03/08/2019] [Indexed: 06/09/2023]
Abstract
Measurements of quantum systems inevitably involve disturbance in various forms. Within the limits imposed by quantum mechanics, there exists an ideal projective measurement that does not introduce a back action on the measured observable, known as a quantum non-demolition (QND) measurement1,2. Here we demonstrate an all-electrical QND measurement of a single electron spin in a gate-defined quantum dot. We entangle the single spin with a two-electron, singlet-triplet ancilla qubit via the exchange interaction3,4 and then read out the ancilla in a single shot. This procedure realizes a disturbance-free projective measurement of the single spin at a rate two orders of magnitude faster than its relaxation. The QND nature of the measurement protocol5,6 enables enhancement of the overall measurement fidelity by repeating the protocol. We demonstrate a monotonic increase of the fidelity over 100 repetitions against arbitrary input states. Our analysis based on statistical inference is tolerant to the presence of the relaxation and dephasing. We further exemplify the QND character of the measurement by observing spontaneous flips (quantum jumps)7 of a single electron spin. Combined with the high-fidelity control of spin qubits8-13, these results will allow for various measurement-based quantum state manipulations including quantum error correction protocols14.
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Affiliation(s)
- Takashi Nakajima
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan.
| | - Akito Noiri
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan
| | - Jun Yoneda
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan
| | - Matthieu R Delbecq
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan
- Laboratoire de Physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Peter Stano
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan
- Institute of Physics, Slovak Academy of Sciences, Bratislava, Slovakia
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Tomohiro Otsuka
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan
- JST, PRESTO, Kawaguchi, Saitama, Japan
- Research Institute of Electrical Communication, Tohoku University, Aoba-ku, Sendai, Japan
| | - Kenta Takeda
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan
| | - Shinichi Amaha
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan
| | - Giles Allison
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan
| | - Kento Kawasaki
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Daniel Loss
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan
- Department of Physics, University of Basel, Basel, Switzerland
| | - Seigo Tarucha
- Center for Emergent Matter Science, RIKEN, Wako-shi, Saitama, Japan.
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
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16
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Ikonen J, Goetz J, Ilves J, Keränen A, Gunyho AM, Partanen M, Tan KY, Hazra D, Grönberg L, Vesterinen V, Simbierowicz S, Hassel J, Möttönen M. Qubit Measurement by Multichannel Driving. PHYSICAL REVIEW LETTERS 2019; 122:080503. [PMID: 30932559 DOI: 10.1103/physrevlett.122.080503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 11/13/2018] [Indexed: 06/09/2023]
Abstract
We theoretically propose and experimentally implement a method of measuring a qubit by driving it close to the frequency of a dispersively coupled bosonic mode. The separation of the bosonic states corresponding to different qubit states begins essentially immediately at maximum rate, leading to a speedup in the measurement protocol. Also the bosonic mode can be simultaneously driven to optimize measurement speed and fidelity. We experimentally test this measurement protocol using a superconducting qubit coupled to a resonator mode. For a certain measurement time, we observe that the conventional dispersive readout yields close to 100% higher average measurement error than our protocol. Finally, we use an additional resonator drive to leave the resonator state to vacuum if the qubit is in the ground state during the measurement protocol. This suggests that the proposed measurement technique may become useful in unconditionally resetting the resonator to a vacuum state after the measurement pulse.
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Affiliation(s)
- Joni Ikonen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Jan Goetz
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Jesper Ilves
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Aarne Keränen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Andras M Gunyho
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Matti Partanen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Kuan Y Tan
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Dibyendu Hazra
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
| | - Leif Grönberg
- VTT Technical Research Centre of Finland, QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland
| | - Visa Vesterinen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
- VTT Technical Research Centre of Finland, QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland
| | - Slawomir Simbierowicz
- VTT Technical Research Centre of Finland, QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland
| | - Juha Hassel
- VTT Technical Research Centre of Finland, QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland
| | - Mikko Möttönen
- QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
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17
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Magnard P, Kurpiers P, Royer B, Walter T, Besse JC, Gasparinetti S, Pechal M, Heinsoo J, Storz S, Blais A, Wallraff A. Fast and Unconditional All-Microwave Reset of a Superconducting Qubit. PHYSICAL REVIEW LETTERS 2018; 121:060502. [PMID: 30141638 DOI: 10.1103/physrevlett.121.060502] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Indexed: 06/08/2023]
Abstract
Active qubit reset is a key operation in many quantum algorithms, and particularly in quantum error correction. Here, we experimentally demonstrate a reset scheme for a three-level transmon artificial atom coupled to a large bandwidth resonator. The reset protocol uses a microwave-induced interaction between the |f,0⟩ and |g,1⟩ states of the coupled transmon-resonator system, with |g⟩ and |f⟩ denoting the ground and second excited states of the transmon, and |0⟩ and |1⟩ the photon Fock states of the resonator. We characterize the reset process and demonstrate reinitialization of the transmon-resonator system to its ground state in less than 500 ns and with 0.2% residual excitation. Our protocol is of practical interest as it has no additional architectural requirements beyond those needed for fast and efficient single-shot readout of transmons, and does not require feedback.
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Affiliation(s)
- P Magnard
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - P Kurpiers
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - B Royer
- Institut Quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - T Walter
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - J-C Besse
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - S Gasparinetti
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - M Pechal
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - J Heinsoo
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - S Storz
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - A Blais
- Institut Quantique and Département de Physique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario M5G IZ8, Canada
| | - A Wallraff
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
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18
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Multiqubit and multilevel quantum reinforcement learning with quantum technologies. PLoS One 2018; 13:e0200455. [PMID: 30024914 PMCID: PMC6053154 DOI: 10.1371/journal.pone.0200455] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/25/2018] [Indexed: 11/19/2022] Open
Abstract
We propose a protocol to perform quantum reinforcement learning with quantum technologies. At variance with recent results on quantum reinforcement learning with superconducting circuits, in our current protocol coherent feedback during the learning process is not required, enabling its implementation in a wide variety of quantum systems. We consider diverse possible scenarios for an agent, an environment, and a register that connects them, involving multiqubit and multilevel systems, as well as open-system dynamics. We finally propose possible implementations of this protocol in trapped ions and superconducting circuits. The field of quantum reinforcement learning with quantum technologies will enable enhanced quantum control, as well as more efficient machine learning calculations.
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19
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Masuyama Y, Funo K, Murashita Y, Noguchi A, Kono S, Tabuchi Y, Yamazaki R, Ueda M, Nakamura Y. Information-to-work conversion by Maxwell's demon in a superconducting circuit quantum electrodynamical system. Nat Commun 2018; 9:1291. [PMID: 29599432 PMCID: PMC5876355 DOI: 10.1038/s41467-018-03686-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 03/05/2018] [Indexed: 11/30/2022] Open
Abstract
Information thermodynamics bridges information theory and statistical physics by connecting information content and entropy production through measurement and feedback control. Maxwell’s demon is a hypothetical character that uses information about a system to reduce its entropy. Here we realize a Maxwell’s demon acting on a superconducting quantum circuit. We implement quantum non-demolition projective measurement and feedback operation of a qubit and verify the generalized integral fluctuation theorem. We also evaluate the conversion efficiency from information gain to work in the feedback protocol. Our experiment constitutes a step toward experimental studies of quantum information thermodynamics in artificially made quantum machines. Maxwell’s demon is a hypothetical character that uses information about a system to reduce its entropy, highlighting the link between information and thermodynamic entropies. Here the authors experimentally realise a Maxwell's demon controlling a quantum system and explore how it affects thermodynamic laws.
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Affiliation(s)
- Y Masuyama
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan
| | - K Funo
- School of Physics, Peking University, Beijing, 100871, China
| | - Y Murashita
- Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - A Noguchi
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan
| | - S Kono
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan
| | - Y Tabuchi
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan
| | - R Yamazaki
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan
| | - M Ueda
- Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.,Center for Emergent Matter Science (CEMS), RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Y Nakamura
- Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan. .,Center for Emergent Matter Science (CEMS), RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
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20
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Wendin G. Quantum information processing with superconducting circuits: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:106001. [PMID: 28682303 DOI: 10.1088/1361-6633/aa7e1a] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
During the last ten years, superconducting circuits have passed from being interesting physical devices to becoming contenders for near-future useful and scalable quantum information processing (QIP). Advanced quantum simulation experiments have been shown with up to nine qubits, while a demonstration of quantum supremacy with fifty qubits is anticipated in just a few years. Quantum supremacy means that the quantum system can no longer be simulated by the most powerful classical supercomputers. Integrated classical-quantum computing systems are already emerging that can be used for software development and experimentation, even via web interfaces. Therefore, the time is ripe for describing some of the recent development of superconducting devices, systems and applications. As such, the discussion of superconducting qubits and circuits is limited to devices that are proven useful for current or near future applications. Consequently, the centre of interest is the practical applications of QIP, such as computation and simulation in Physics and Chemistry.
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Affiliation(s)
- G Wendin
- Department of Microtechnology and Nanoscience-MC2, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
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21
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Ryan CA, Johnson BR, Ristè D, Donovan B, Ohki TA. Hardware for dynamic quantum computing. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:104703. [PMID: 29092485 DOI: 10.1063/1.5006525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 09/24/2017] [Indexed: 06/07/2023]
Abstract
We describe the hardware, gateware, and software developed at Raytheon BBN Technologies for dynamic quantum information processing experiments on superconducting qubits. In dynamic experiments, real-time qubit state information is fed back or fed forward within a fraction of the qubits' coherence time to dynamically change the implemented sequence. The hardware presented here covers both control and readout of superconducting qubits. For readout, we created a custom signal processing gateware and software stack on commercial hardware to convert pulses in a heterodyne receiver into qubit state assignments with minimal latency, alongside data taking capability. For control, we developed custom hardware with gateware and software for pulse sequencing and steering information distribution that is capable of arbitrary control flow in a fraction of superconducting qubit coherence times. Both readout and control platforms make extensive use of field programmable gate arrays to enable tailored qubit control systems in a reconfigurable fabric suitable for iterative development.
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Affiliation(s)
- Colm A Ryan
- Raytheon BBN Technologies, Cambridge, Massachusetts 02138, USA
| | - Blake R Johnson
- Raytheon BBN Technologies, Cambridge, Massachusetts 02138, USA
| | - Diego Ristè
- Raytheon BBN Technologies, Cambridge, Massachusetts 02138, USA
| | - Brian Donovan
- Raytheon BBN Technologies, Cambridge, Massachusetts 02138, USA
| | - Thomas A Ohki
- Raytheon BBN Technologies, Cambridge, Massachusetts 02138, USA
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22
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Lamata L. Basic protocols in quantum reinforcement learning with superconducting circuits. Sci Rep 2017; 7:1609. [PMID: 28487535 PMCID: PMC5431677 DOI: 10.1038/s41598-017-01711-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/03/2017] [Indexed: 11/08/2022] Open
Abstract
Superconducting circuit technologies have recently achieved quantum protocols involving closed feedback loops. Quantum artificial intelligence and quantum machine learning are emerging fields inside quantum technologies which may enable quantum devices to acquire information from the outer world and improve themselves via a learning process. Here we propose the implementation of basic protocols in quantum reinforcement learning, with superconducting circuits employing feedback- loop control. We introduce diverse scenarios for proof-of-principle experiments with state-of-the-art superconducting circuit technologies and analyze their feasibility in presence of imperfections. The field of quantum artificial intelligence implemented with superconducting circuits paves the way for enhanced quantum control and quantum computation protocols.
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Affiliation(s)
- Lucas Lamata
- Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, 48080, Bilbao, Spain.
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23
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Abstract
Quantum technology promises revolutionizing applications in information processing, communications, sensing and modelling. However, efficient on-demand cooling of the functional quantum degrees of freedom remains challenging in many solid-state implementations, such as superconducting circuits. Here we demonstrate direct cooling of a superconducting resonator mode using voltage-controllable electron tunnelling in a nanoscale refrigerator. This result is revealed by a decreased electron temperature at a resonator-coupled probe resistor, even for an elevated electron temperature at the refrigerator. Our conclusions are verified by control experiments and by a good quantitative agreement between theory and experimental observations at various operation voltages and bath temperatures. In the future, we aim to remove spurious dissipation introduced by our refrigerator and to decrease the operational temperature. Such an ideal quantum-circuit refrigerator has potential applications in the initialization of quantum electric devices. In the superconducting quantum computer, for example, fast and accurate reset of the quantum memory is needed. Efficient on-demand cooling of the functional degrees of freedom in solid-state implementations of quantum information processing devices remains a challenge. Here the authors demonstrate direct cooling of a photonic mode of a superconducting resonator using voltage-controllable electron tunnelling.
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24
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Purification of an unpolarized spin ensemble into entangled singlet pairs. Sci Rep 2017; 7:529. [PMID: 28373720 PMCID: PMC5428879 DOI: 10.1038/s41598-017-00603-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 03/07/2017] [Indexed: 11/09/2022] Open
Abstract
Dynamical polarization of nuclear spin ensembles is of central importance for magnetic resonance studies, precision sensing and for applications in quantum information theory. Here we propose a scheme to generate long-lived singlet pairs in an unpolarized nuclear spin ensemble which is dipolar coupled to the electron spins of a Nitrogen Vacancy center in diamond. The quantum mechanical back-action induced by frequent spin-selective readout of the NV centers allows the nuclear spins to pair up into maximally entangled singlet pairs. Counterintuitively, the robustness of the pair formation to dephasing noise improves with increasing size of the spin ensemble. We also show how the paired nuclear spin state allows for enhanced sensing capabilities of NV centers in diamond.
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25
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Campagne-Ibarcq P, Jezouin S, Cottet N, Six P, Bretheau L, Mallet F, Sarlette A, Rouchon P, Huard B. Using Spontaneous Emission of a Qubit as a Resource for Feedback Control. PHYSICAL REVIEW LETTERS 2016; 117:060502. [PMID: 27541448 DOI: 10.1103/physrevlett.117.060502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Indexed: 06/06/2023]
Abstract
Persistent control of a transmon qubit is performed by a feedback protocol based on continuous heterodyne measurement of its fluorescence. By driving the qubit and cavity with microwave signals whose amplitudes depend linearly on the instantaneous values of the quadratures of the measured fluorescence field, we show that it is possible to stabilize permanently the qubit in any targeted state. Using a Josephson mixer as a phase-preserving amplifier, it was possible to reach a total measurement efficiency η=35%, leading to a maximum of 59% of excitation and 44% of coherence for the stabilized states. The experiment demonstrates multiple-input multiple-output analog Markovian feedback in the quantum regime.
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Affiliation(s)
- P Campagne-Ibarcq
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France
- Quantic Team, INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
| | - S Jezouin
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France
- Quantic Team, INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
| | - N Cottet
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France
- Quantic Team, INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
| | - P Six
- Quantic Team, INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
- Centre Automatique et Systèmes, Mines ParisTech, PSL Research University, 60 Boulevard Saint-Michel, 75272 Paris Cedex 6, France
| | - L Bretheau
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France
- Quantic Team, INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
| | - F Mallet
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France
- Quantic Team, INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
| | - A Sarlette
- Quantic Team, INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
| | - P Rouchon
- Quantic Team, INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
- Centre Automatique et Systèmes, Mines ParisTech, PSL Research University, 60 Boulevard Saint-Michel, 75272 Paris Cedex 6, France
| | - B Huard
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure-PSL Research University, CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Université Paris Diderot-Sorbonne Paris Cité, 24 rue Lhomond, 75231 Paris Cedex 05, France
- Quantic Team, INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
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26
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Abstract
Feedback loops are known as a versatile tool for controlling transport in small systems, which usually have large intrinsic fluctuations. Here we investigate the control of a temporal correlation function, the waiting-time distribution, under active and passive feedback conditions. We develop a general formalism and then specify to the simple unidirectional transport model, where we compare costs of open-loop and feedback control and use methods from optimal control theory to optimize waiting-time distributions.
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Affiliation(s)
- Tobias Brandes
- Institut für Theoretische Physik, Hardenbergstr. 36, TU Berlin, D-10623 Berlin, Germany
| | - Clive Emary
- Joint Quantum Centre Durham-Newcastle, School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
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27
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Holland ET, Vlastakis B, Heeres RW, Reagor MJ, Vool U, Leghtas Z, Frunzio L, Kirchmair G, Devoret MH, Mirrahimi M, Schoelkopf RJ. Single-Photon-Resolved Cross-Kerr Interaction for Autonomous Stabilization of Photon-Number States. PHYSICAL REVIEW LETTERS 2015; 115:180501. [PMID: 26565448 DOI: 10.1103/physrevlett.115.180501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Indexed: 06/05/2023]
Abstract
Quantum states can be stabilized in the presence of intrinsic and environmental losses by either applying an active feedback condition on an ancillary system or through reservoir engineering. Reservoir engineering maintains a desired quantum state through a combination of drives and designed entropy evacuation. We propose and implement a quantum-reservoir engineering protocol that stabilizes Fock states in a microwave cavity. This protocol is realized with a circuit quantum electrodynamics platform where a Josephson junction provides direct, nonlinear coupling between two superconducting waveguide cavities. The nonlinear coupling results in a single-photon-resolved cross-Kerr effect between the two cavities enabling a photon-number-dependent coupling to a lossy environment. The quantum state of the microwave cavity is discussed in terms of a net polarization and is analyzed by a measurement of its steady state Wigner function.
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Affiliation(s)
- E T Holland
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - B Vlastakis
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - R W Heeres
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - M J Reagor
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - U Vool
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Z Leghtas
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - L Frunzio
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - G Kirchmair
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Experimental Physics, University of Innsbruck, A-6020 Innsbruck, Austria
| | - M H Devoret
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - M Mirrahimi
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
- INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay Cedex, France
| | - R J Schoelkopf
- Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520, USA
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28
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Leghtas Z, Touzard S, Pop IM, Kou A, Vlastakis B, Petrenko A, Sliwa KM, Narla A, Shankar S, Hatridge MJ, Reagor M, Frunzio L, Schoelkopf RJ, Mirrahimi M, Devoret MH. Confining the state of light to a quantum manifold by engineered two-photon loss. Science 2015; 347:853-7. [DOI: 10.1126/science.aaa2085] [Citation(s) in RCA: 262] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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29
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Eichler C, Salathe Y, Mlynek J, Schmidt S, Wallraff A. Quantum-limited amplification and entanglement in coupled nonlinear resonators. PHYSICAL REVIEW LETTERS 2014; 113:110502. [PMID: 25259964 DOI: 10.1103/physrevlett.113.110502] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Indexed: 06/03/2023]
Abstract
We demonstrate a coupled cavity realization of a Bose-Hubbard dimer to achieve quantum-limited amplification and to generate frequency entangled microwave fields with squeezing parameters well below -12 dB. In contrast to previous implementations of parametric amplifiers, our dimer can be operated both as a degenerate and as a nondegenerate amplifier. The large measured gain-bandwidth product of more than 250 MHz for the nondegenerate operation and the saturation at input photon numbers as high as 2000 per μs are both expected to be improvable even further, while maintaining wide frequency tunability of about 2 GHz. Featuring flexible control over all relevant system parameters, the presented Bose-Hubbard dimer based on lumped element circuits has significant potential as an elementary cell in nonlinear cavity arrays for quantum simulations.
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Affiliation(s)
- C Eichler
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Y Salathe
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - J Mlynek
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - S Schmidt
- Institute for Theoretical Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - A Wallraff
- Department of Physics, ETH Zürich, CH-8093 Zürich, Switzerland
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30
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Lucas F, Hornberger K. Incoherent control of the retinal isomerization in rhodopsin. PHYSICAL REVIEW LETTERS 2014; 113:058301. [PMID: 25126938 DOI: 10.1103/physrevlett.113.058301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Indexed: 06/03/2023]
Abstract
We propose to control the retinal photoisomerization yield through the backaction dynamics imparted by a nonselective optical measurement of the molecular electronic state. This incoherent effect is easier to implement than comparable coherent pulse shaping techniques, and is also robust to environmental noise. A numerical simulation of the quantum dynamics shows that the isomerization yield of this important biomolecule can be substantially increased above the natural limit.
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Affiliation(s)
- Felix Lucas
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany and University of Duisburg-Essen, Faculty of Physics, Lotharstraße 1-21, 47057 Duisburg, Germany
| | - Klaus Hornberger
- University of Duisburg-Essen, Faculty of Physics, Lotharstraße 1-21, 47057 Duisburg, Germany
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31
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Campagne-Ibarcq P, Bretheau L, Flurin E, Auffèves A, Mallet F, Huard B. Observing interferences between past and future quantum states in resonance fluorescence. PHYSICAL REVIEW LETTERS 2014; 112:180402. [PMID: 24856677 DOI: 10.1103/physrevlett.112.180402] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Indexed: 06/03/2023]
Abstract
The fluorescence of a resonantly driven superconducting qubit is measured in the time domain, providing a weak probe of the qubit dynamics. Prior preparation and final, single-shot measurement of the qubit allows us to average fluorescence records conditionally on past and future knowledge. The resulting interferences reveal purely quantum features characteristic of weak values. We demonstrate conditional averages that go beyond classical boundaries and probe directly the jump operator associated with relaxation. The experimental results are remarkably captured by a recent theory, which generalizes quantum mechanics to open quantum systems whose past and future are known.
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Affiliation(s)
- P Campagne-Ibarcq
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France
| | - L Bretheau
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France
| | - E Flurin
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France
| | - A Auffèves
- CNRS and Université Grenoble Alpes, Institut Néel, 38042 Grenoble, France
| | - F Mallet
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France
| | - B Huard
- Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France
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32
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Reducing the impact of intrinsic dissipation in a superconducting circuit by quantum error detection. Nat Commun 2014; 5:3135. [DOI: 10.1038/ncomms4135] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Accepted: 12/17/2013] [Indexed: 11/08/2022] Open
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33
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Observing single quantum trajectories of a superconducting quantum bit. Nature 2013; 502:211-4. [PMID: 24108052 DOI: 10.1038/nature12539] [Citation(s) in RCA: 258] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 08/07/2013] [Indexed: 11/08/2022]
Abstract
The length of time that a quantum system can exist in a superposition state is determined by how strongly it interacts with its environment. This interaction entangles the quantum state with the inherent fluctuations of the environment. If these fluctuations are not measured, the environment can be viewed as a source of noise, causing random evolution of the quantum system from an initially pure state into a statistical mixture--a process known as decoherence. However, by accurately measuring the environment in real time, the quantum system can be maintained in a pure state and its time evolution described by a 'quantum trajectory' determined by the measurement outcome. Here we use weak measurements to monitor a microwave cavity containing a superconducting quantum bit (qubit), and track the individual quantum trajectories of the system. In this set-up, the environment is dominated by the fluctuations of a single electromagnetic mode of the cavity. Using a near-quantum-limited parametric amplifier, we selectively measure either the phase or the amplitude of the cavity field, and thereby confine trajectories to either the equator or a meridian of the Bloch sphere. We perform quantum state tomography at discrete times along the trajectory to verify that we have faithfully tracked the state of the quantum system as it diffuses on the surface of the Bloch sphere. Our results demonstrate that decoherence can be mitigated by environmental monitoring, and validate the foundation of quantum feedback approaches based on Bayesian statistics. Moreover, our experiments suggest a new means of implementing 'quantum steering'--the harnessing of action at a distance to manipulate quantum states through measurement.
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34
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Strasberg P, Schaller G, Brandes T, Esposito M. Thermodynamics of quantum-jump-conditioned feedback control. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:062107. [PMID: 24483386 DOI: 10.1103/physreve.88.062107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Indexed: 06/03/2023]
Abstract
We consider open quantum systems weakly coupled to thermal reservoirs and subjected to quantum feedback operations triggered with or without delay by monitored quantum jumps. We establish a thermodynamic description of such systems and analyze how the first and second law of thermodynamics are modified by the feedback. We apply our formalism to study the efficiency of a qubit subjected to a quantum feedback control and operating as a heat pump between two reservoirs. We also demonstrate that quantum feedbacks can be used to stabilize coherences in nonequilibrium stationary states which in some cases may even become pure quantum states.
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Affiliation(s)
- Philipp Strasberg
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany
| | - Gernot Schaller
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany
| | - Tobias Brandes
- Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany
| | - Massimiliano Esposito
- Complex Systems and Statistical Mechanics, University of Luxembourg, L-1511 Luxembourg, Luxembourg
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35
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Dissipative production of a maximally entangled steady state of two quantum bits. Nature 2013; 504:415-8. [DOI: 10.1038/nature12801] [Citation(s) in RCA: 270] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 10/16/2013] [Indexed: 12/26/2022]
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36
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Shankar S, Hatridge M, Leghtas Z, Sliwa KM, Narla A, Vool U, Girvin SM, Frunzio L, Mirrahimi M, Devoret MH. Autonomously stabilized entanglement between two superconducting quantum bits. Nature 2013; 504:419-22. [PMID: 24270808 DOI: 10.1038/nature12802] [Citation(s) in RCA: 234] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 10/22/2013] [Indexed: 12/27/2022]
Abstract
Quantum error correction codes are designed to protect an arbitrary state of a multi-qubit register from decoherence-induced errors, but their implementation is an outstanding challenge in the development of large-scale quantum computers. The first step is to stabilize a non-equilibrium state of a simple quantum system, such as a quantum bit (qubit) or a cavity mode, in the presence of decoherence. This has recently been accomplished using measurement-based feedback schemes. The next step is to prepare and stabilize a state of a composite system. Here we demonstrate the stabilization of an entangled Bell state of a quantum register of two superconducting qubits for an arbitrary time. Our result is achieved using an autonomous feedback scheme that combines continuous drives along with a specifically engineered coupling between the two-qubit register and a dissipative reservoir. Similar autonomous feedback techniques have been used for qubit reset, single-qubit state stabilization, and the creation and stabilization of states of multipartite quantum systems. Unlike conventional, measurement-based schemes, the autonomous approach uses engineered dissipation to counteract decoherence, obviating the need for a complicated external feedback loop to correct errors. Instead, the feedback loop is built into the Hamiltonian such that the steady state of the system in the presence of drives and dissipation is a Bell state, an essential building block for quantum information processing. Such autonomous schemes, which are broadly applicable to a variety of physical systems, as demonstrated by the accompanying paper on trapped ion qubits, will be an essential tool for the implementation of quantum error correction.
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Affiliation(s)
- S Shankar
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - M Hatridge
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Z Leghtas
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - K M Sliwa
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - A Narla
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - U Vool
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - S M Girvin
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - L Frunzio
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
| | - M Mirrahimi
- 1] Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA [2] INRIA Paris-Rocquencourt, Domaine de Voluceau, BP 105, 78153 Le Chesnay Cedex, France
| | - M H Devoret
- Department of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA
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37
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Deterministic entanglement of superconducting qubits by parity measurement and feedback. Nature 2013; 502:350-4. [DOI: 10.1038/nature12513] [Citation(s) in RCA: 226] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 07/24/2013] [Indexed: 12/25/2022]
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38
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Steffen L, Salathe Y, Oppliger M, Kurpiers P, Baur M, Lang C, Eichler C, Puebla-Hellmann G, Fedorov A, Wallraff A. Deterministic quantum teleportation with feed-forward in a solid state system. Nature 2013; 500:319-22. [PMID: 23955231 DOI: 10.1038/nature12422] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Accepted: 06/28/2013] [Indexed: 11/09/2022]
Abstract
Engineered macroscopic quantum systems based on superconducting electronic circuits are attractive for experimentally exploring diverse questions in quantum information science. At the current state of the art, quantum bits (qubits) are fabricated, initialized, controlled, read out and coupled to each other in simple circuits. This enables the realization of basic logic gates, the creation of complex entangled states and the demonstration of algorithms or error correction. Using different variants of low-noise parametric amplifiers, dispersive quantum non-demolition single-shot readout of single-qubit states with high fidelity has enabled continuous and discrete feedback control of single qubits. Here we realize full deterministic quantum teleportation with feed-forward in a chip-based superconducting circuit architecture. We use a set of two parametric amplifiers for both joint two-qubit and individual qubit single-shot readout, combined with flexible real-time digital electronics. Our device uses a crossed quantum bus technology that allows us to create complex networks with arbitrary connecting topology in a planar architecture. The deterministic teleportation process succeeds with order unit probability for any input state, as we prepare maximally entangled two-qubit states as a resource and distinguish all Bell states in a single two-qubit measurement with high efficiency and high fidelity. We teleport quantum states between two macroscopic systems separated by 6 mm at a rate of 10(4) s(-1), exceeding other reported implementations. The low transmission loss of superconducting waveguides is likely to enable the range of this and other schemes to be extended to significantly larger distances, enabling tests of non-locality and the realization of elements for quantum communication at microwave frequencies. The demonstrated feed-forward may also find application in error correction schemes.
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Affiliation(s)
- L Steffen
- Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland.
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39
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Wenner J, Yin Y, Lucero E, Barends R, Chen Y, Chiaro B, Kelly J, Lenander M, Mariantoni M, Megrant A, Neill C, O'Malley PJJ, Sank D, Vainsencher A, Wang H, White TC, Cleland AN, Martinis JM. Excitation of superconducting qubits from hot nonequilibrium quasiparticles. PHYSICAL REVIEW LETTERS 2013; 110:150502. [PMID: 25167235 DOI: 10.1103/physrevlett.110.150502] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 03/04/2013] [Indexed: 06/03/2023]
Abstract
Superconducting qubits probe environmental defects such as nonequilibrium quasiparticles, an important source of decoherence. We show that "hot" nonequilibrium quasiparticles, with energies above the superconducting gap, affect qubits differently from quasiparticles at the gap, implying qubits can probe the dynamic quasiparticle energy distribution. For hot quasiparticles, we predict a non-negligible increase in the qubit excited state probability Pe. By injecting hot quasiparticles into a qubit, we experimentally measure an increase of Pe in semiquantitative agreement with the model and rule out the typically assumed thermal distribution.
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Affiliation(s)
- J Wenner
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - Yi Yin
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - Erik Lucero
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - R Barends
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - Yu Chen
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - B Chiaro
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - J Kelly
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - M Lenander
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - Matteo Mariantoni
- Department of Physics, University of California, Santa Barbara, California 93106, USA and California NanoSystems Institute, University of California, Santa Barbara, California 93106, USA
| | - A Megrant
- Department of Physics, University of California, Santa Barbara, California 93106, USA and Department of Materials, University of California, Santa Barbara, California 93106, USA
| | - C Neill
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - P J J O'Malley
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - D Sank
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - A Vainsencher
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - H Wang
- Department of Physics, University of California, Santa Barbara, California 93106, USA and Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - T C White
- Department of Physics, University of California, Santa Barbara, California 93106, USA
| | - A N Cleland
- Department of Physics, University of California, Santa Barbara, California 93106, USA and California NanoSystems Institute, University of California, Santa Barbara, California 93106, USA
| | - John M Martinis
- Department of Physics, University of California, Santa Barbara, California 93106, USA and California NanoSystems Institute, University of California, Santa Barbara, California 93106, USA
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40
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Geerlings K, Leghtas Z, Pop IM, Shankar S, Frunzio L, Schoelkopf RJ, Mirrahimi M, Devoret MH. Demonstrating a driven reset protocol for a superconducting qubit. PHYSICAL REVIEW LETTERS 2013; 110:120501. [PMID: 25166782 DOI: 10.1103/physrevlett.110.120501] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Indexed: 06/03/2023]
Abstract
Qubit reset is crucial at the start of and during quantum information algorithms. We present the experimental demonstration of a practical method to force qubits into their ground state, based on driving appropriate qubit and cavity transitions. Our protocol, called the double drive reset of population, is tested on a superconducting transmon qubit in a three-dimensional cavity. Using a new method for measuring population, we show that we can prepare the ground state with a fidelity of at least 99.5% in less than 3 μs; faster times and higher fidelity are predicted upon parameter optimization.
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Affiliation(s)
- K Geerlings
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520-8284, USA
| | - Z Leghtas
- INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay cedex, France
| | - I M Pop
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520-8284, USA
| | - S Shankar
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520-8284, USA
| | - L Frunzio
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520-8284, USA
| | - R J Schoelkopf
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520-8284, USA
| | - M Mirrahimi
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520-8284, USA and INRIA Paris-Rocquencourt, Domaine de Voluceau, B.P. 105, 78153 Le Chesnay cedex, France
| | - M H Devoret
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520-8284, USA
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41
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Devoret MH, Schoelkopf RJ. Superconducting Circuits for Quantum Information: An Outlook. Science 2013; 339:1169-74. [DOI: 10.1126/science.1231930] [Citation(s) in RCA: 1301] [Impact Index Per Article: 118.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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42
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Ristè D, Bultink CC, Tiggelman MJ, Schouten RN, Lehnert KW, DiCarlo L. Millisecond charge-parity fluctuations and induced decoherence in a superconducting transmon qubit. Nat Commun 2013; 4:1913. [PMID: 23715272 PMCID: PMC3674283 DOI: 10.1038/ncomms2936] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Accepted: 04/29/2013] [Indexed: 11/24/2022] Open
Abstract
The tunnelling of quasiparticles across Josephson junctions in superconducting quantum circuits is an intrinsic decoherence mechanism for qubit degrees of freedom. Understanding the limits imposed by quasiparticle tunnelling on qubit relaxation and dephasing is of theoretical and experimental interest, particularly as improved understanding of extrinsic mechanisms has allowed crossing the 100 microsecond mark in transmon-type charge qubits. Here, by integrating recent developments in high-fidelity qubit readout and feedback control in circuit quantum electrodynamics, we transform a state-of-the-art transmon into its own real-time charge-parity detector. We directly measure the tunnelling of quasiparticles across the single junction and isolate the contribution of this tunnelling to qubit relaxation and dephasing, without reliance on theory. The millisecond timescales measured demonstrate that quasiparticle tunnelling does not presently bottleneck transmon qubit coherence, leaving room for yet another order of magnitude increase.
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Affiliation(s)
- D. Ristè
- Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
| | - C. C. Bultink
- Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
| | - M. J. Tiggelman
- Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
| | - R. N. Schouten
- Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
| | - K. W. Lehnert
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - L. DiCarlo
- Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands
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