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Strandberg I, Eriksson AM, Royer B, Kervinen M, Gasparinetti S. Digital Homodyne and Heterodyne Detection for Stationary Bosonic Modes. PHYSICAL REVIEW LETTERS 2024; 133:063601. [PMID: 39178427 DOI: 10.1103/physrevlett.133.063601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 03/20/2024] [Accepted: 07/09/2024] [Indexed: 08/25/2024]
Abstract
Homo- and heterodyne detection are fundamental techniques for measuring propagating electromagnetic fields. However, applying these techniques to stationary fields confined in cavities poses a challenge. As a way to overcome this challenge, we propose to use repeated indirect measurements of a two-level system interacting with the cavity. We demonstrate numerically that the proposed measurement scheme faithfully reproduces measurement statistics of homo- or heterodyne detection. The scheme can be implemented in various physical architectures, including circuit quantum electrodynamics. Our results pave the way for implementation of quantum algorithms requiring linear detection of stationary modes, including quantum verification protocols.
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Viotti L, Lombardo FC, Villar PI. Geometric Phase of a Transmon in a Dissipative Quantum Circuit. ENTROPY (BASEL, SWITZERLAND) 2024; 26:89. [PMID: 38275497 PMCID: PMC10814483 DOI: 10.3390/e26010089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 01/27/2024]
Abstract
Superconducting circuits reveal themselves as promising physical devices with multiple uses. Within those uses, the fundamental concept of the geometric phase accumulated by the state of a system shows up recurrently, as, for example, in the construction of geometric gates. Given this framework, we study the geometric phases acquired by a paradigmatic setup: a transmon coupled to a superconductor resonating cavity. We do so both for the case in which the evolution is unitary and when it is subjected to dissipative effects. These models offer a comprehensive quantum description of an anharmonic system interacting with a single mode of the electromagnetic field within a perfect or dissipative cavity, respectively. In the dissipative model, the non-unitary effects arise from dephasing, relaxation, and decay of the transmon coupled to its environment. Our approach enables a comparison of the geometric phases obtained in these models, leading to a thorough understanding of the corrections introduced by the presence of the environment.
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Affiliation(s)
- Ludmila Viotti
- The Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34151 Trieste, Italy
| | - Fernando C. Lombardo
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
- Instituto de Física de Buenos Aires (IFIBA), CONICET—Universidad de Buenos Aires, Buenos Aires 1428, Argentina
| | - Paula I. Villar
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires 1428, Argentina
- Instituto de Física de Buenos Aires (IFIBA), CONICET—Universidad de Buenos Aires, Buenos Aires 1428, Argentina
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Xu Y, Hua Z, Chen T, Pan X, Li X, Han J, Cai W, Ma Y, Wang H, Song YP, Xue ZY, Sun L. Experimental Implementation of Universal Nonadiabatic Geometric Quantum Gates in a Superconducting Circuit. PHYSICAL REVIEW LETTERS 2020; 124:230503. [PMID: 32603172 DOI: 10.1103/physrevlett.124.230503] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
Using geometric phases to realize noise-resilient quantum computing is an important method to enhance the control fidelity. In this work, we experimentally realize a universal nonadiabatic geometric quantum gate set in a superconducting qubit chain. We characterize the realized single- and two-qubit geometric gates with both quantum process tomography and randomized benchmarking methods. The measured average fidelities for the single-qubit rotation gates and two-qubit controlled-Z gate are 0.9977(1) and 0.977(9), respectively. Besides, we also experimentally demonstrate the noise-resilient feature of the realized single-qubit geometric gates by comparing their performance with the conventional dynamical gates with different types of errors in the control field. Thus, our experiment proves a way to achieve high-fidelity geometric quantum gates for robust quantum computation.
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Affiliation(s)
- Y Xu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Z Hua
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Tao Chen
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, GPETR Center for Quantum Precision Measurement, and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
| | - X Pan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - X Li
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - J Han
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - W Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y Ma
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - H Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Y P Song
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
| | - Zheng-Yuan Xue
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, GPETR Center for Quantum Precision Measurement, and School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
| | - L Sun
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, China
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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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Ferraro D, Campisi M, Andolina GM, Pellegrini V, Polini M. High-Power Collective Charging of a Solid-State Quantum Battery. PHYSICAL REVIEW LETTERS 2018; 120:117702. [PMID: 29601745 DOI: 10.1103/physrevlett.120.117702] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Indexed: 05/28/2023]
Abstract
Quantum information theorems state that it is possible to exploit collective quantum resources to greatly enhance the charging power of quantum batteries (QBs) made of many identical elementary units. We here present and solve a model of a QB that can be engineered in solid-state architectures. It consists of N two-level systems coupled to a single photonic mode in a cavity. We contrast this collective model ("Dicke QB"), whereby entanglement is genuinely created by the common photonic mode, to the one in which each two-level system is coupled to its own separate cavity mode ("Rabi QB"). By employing exact diagonalization, we demonstrate the emergence of a quantum advantage in the charging power of Dicke QBs, which scales like sqrt[N] for N≫1.
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Affiliation(s)
- Dario Ferraro
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genova, Italy
| | - Michele Campisi
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genova, Italy
| | - Gian Marcello Andolina
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genova, Italy
- NEST, Scuola Normale Superiore, I-56126 Pisa, Italy
| | - Vittorio Pellegrini
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genova, Italy
| | - Marco Polini
- Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genova, Italy
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A CNOT gate between multiphoton qubits encoded in two cavities. Nat Commun 2018; 9:652. [PMID: 29440766 PMCID: PMC5811561 DOI: 10.1038/s41467-018-03059-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 01/16/2018] [Indexed: 11/08/2022] Open
Abstract
Entangling gates between qubits are a crucial component for performing algorithms in quantum computers. However, any quantum algorithm must ultimately operate on error-protected logical qubits encoded in high-dimensional systems. Typically, logical qubits are encoded in multiple two-level systems, but entangling gates operating on such qubits are highly complex and have not yet been demonstrated. Here we realize a controlled NOT (CNOT) gate between two multiphoton qubits in two microwave cavities. In this approach, we encode a qubit in the high-dimensional space of a single cavity mode, rather than in multiple two-level systems. We couple two such encoded qubits together through a transmon, which is driven by an RF pump to apply the gate within 190 ns. This is two orders of magnitude shorter than the decoherence time of the transmon, enabling a high-fidelity gate operation. These results are an important step towards universal algorithms on error-corrected logical qubits.
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