1
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Alushi U, Górecki W, Felicetti S, Di Candia R. Optimality and Noise Resilience of Critical Quantum Sensing. PHYSICAL REVIEW LETTERS 2024; 133:040801. [PMID: 39121399 DOI: 10.1103/physrevlett.133.040801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 06/10/2024] [Indexed: 08/11/2024]
Abstract
We compare critical quantum sensing to passive quantum strategies to perform frequency estimation, in the case of single-mode quadratic Hamiltonians. We show that, while in the unitary case both strategies achieve precision scaling quadratic with the number of photons, in the presence of dissipation this is true only for critical strategies. We also establish that working at the exceptional point or beyond threshold provides suboptimal performance. This critical enhancement is due to the emergence of a transient regime in the open critical dynamics, and is invariant to temperature changes. When considering both time and system size as resources, for both strategies the precision scales linearly with the product of the total time and the number of photons, in accordance with fundamental bounds. However, we show that critical protocols outperform optimal passive strategies if preparation and measurement times are not negligible. Our results are applicable to a broad variety of critical sensors whose phenomenology can be reduced to that of a single-mode quadratic Hamiltonian, including systems described by finite-component and fully connected models.
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2
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Chen YH, Shi ZC, Nori F, Xia Y. Error-Tolerant Amplification and Simulation of the Ultrastrong-Coupling Quantum Rabi Model. PHYSICAL REVIEW LETTERS 2024; 133:033603. [PMID: 39094163 DOI: 10.1103/physrevlett.133.033603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 06/18/2024] [Indexed: 08/04/2024]
Abstract
Cat-state qubits formed by photonic cat states have a biased noise channel, i.e., one type of error dominates over all the others. We demonstrate that such biased-noise qubits are also promising for error-tolerant simulations of the quantum Rabi model (and its varieties) by coupling a cat-state qubit to an optical cavity. Using the cat-state qubit can effectively enhance the counterrotating coupling, allowing us to explore several fascinating quantum phenomena relying on the counterrotating interaction. Moreover, another benefit from biased-noise cat qubits is that the two main error channels (frequency and amplitude mismatches) are both exponentially suppressed. Therefore, the simulation protocols are robust against parameter errors of the parametric drive that determines the projection subspace. We analyze three examples: (i) collapse and revivals of quantum states; (ii) hidden symmetry and tunneling dynamics; and (iii) pair-cat-code computation.
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Affiliation(s)
- Ye-Hong Chen
- Fujian Key Laboratory of Quantum Information and Quantum Optics, Fuzhou University, Fuzhou 350116, China
- Department of Physics, Fuzhou University, Fuzhou 350116, China
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
| | | | - Franco Nori
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
- Quantum Information Physics Theory Research Team, RIKEN Center for Quantum Computing, Wako-shi, Saitama 351-0198, Japan
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA
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3
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Zhu GL, Hu CS, Wang H, Qin W, Lü XY, Nori F. Nonreciprocal Superradiant Phase Transitions and Multicriticality in a Cavity QED System. PHYSICAL REVIEW LETTERS 2024; 132:193602. [PMID: 38804940 DOI: 10.1103/physrevlett.132.193602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 02/06/2024] [Accepted: 04/01/2024] [Indexed: 05/29/2024]
Abstract
We demonstrate the emergence of nonreciprocal superradiant phase transitions and novel multicriticality in a cavity quantum electrodynamics system, where a two-level atom interacts with two counterpropagating modes of a whispering-gallery-mode microcavity. The cavity rotates at a certain angular velocity and is directionally squeezed by a unidirectional parametric pumping χ^{(2)} nonlinearity. The combination of cavity rotation and directional squeezing leads to nonreciprocal first- and second-order superradiant phase transitions. These transitions do not require ultrastrong atom-field couplings and can be easily controlled by the external pump field. Through a full quantum description of the system Hamiltonian, we identify two types of multicritical points in the phase diagram, both of which exhibit controllable nonreciprocity. These results open a new door for all-optical manipulation of superradiant transitions and multicritical behaviors in light-matter systems, with potential applications in engineering various integrated nonreciprocal quantum devices.
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Affiliation(s)
- Gui-Lei Zhu
- Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018, China
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
| | - Chang-Sheng Hu
- Department of Physics, Anhui Normal University, Wuhu 241000, China
| | - Hui Wang
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
| | - Wei Qin
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, Tianjin 300350, China
| | - Xin-You Lü
- School of Physics, Huazhong University of Science and Technology and Wuhan Institute of Quantum Technology, Wuhan 430074, China
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Quantum Computing Center, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Department of Physics, The University of Michigan, Ann Arbor, Michigan 48109-1040, USA
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4
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Bond LJ, Safavi-Naini A, Minář J. Fast Quantum State Preparation and Bath Dynamics Using Non-Gaussian Variational Ansatz and Quantum Optimal Control. PHYSICAL REVIEW LETTERS 2024; 132:170401. [PMID: 38728702 DOI: 10.1103/physrevlett.132.170401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 01/15/2024] [Accepted: 03/25/2024] [Indexed: 05/12/2024]
Abstract
Fast preparation of quantum many-body states is essential for myriad quantum algorithms and metrological applications. Here, we develop a new pathway for fast, nonadiabatic preparation of quantum many-body states that combines quantum optimal control with a variational Ansatz based on non-Gaussian states. We demonstrate our approach on the spin-boson model, a single spin interacting with the bath. We use a multipolaron Ansatz to prepare near-critical ground states. For one mode, we achieve a reduction in infidelity of up to ≈60 (≈10) times compared to linear (optimized local adiabatic) ramps; for many modes, we achieve a reduction in infidelity of up to ≈5 times compared to nonadiabatic linear ramps. Further, we show that the typical control quantity, the leakage from the variational manifold, provides only a loose bound on the state's fidelity. Instead, in analogy to the bond dimension of matrix product states, we suggest a controlled convergence criterion based on the number of polarons. Finally, motivated by the possibility of realizations in trapped ions, we study the dynamics of a system with bath properties going beyond the paradigm of (sub- and/or super-) Ohmic couplings.
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Affiliation(s)
- Liam J Bond
- Institute for Theoretical Physics, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- QuSoft, Science Park 123, 1098 XG Amsterdam, The Netherlands
| | - Arghavan Safavi-Naini
- Institute for Theoretical Physics, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- QuSoft, Science Park 123, 1098 XG Amsterdam, The Netherlands
| | - Jiří Minář
- Institute for Theoretical Physics, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- QuSoft, Science Park 123, 1098 XG Amsterdam, The Netherlands
- CWI, Science Park 904, 1098 XH Amsterdam, The Netherlands
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5
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Wang Y, Wu YK, Jiang Y, Cai ML, Li BW, Mei QX, Qi BX, Zhou ZC, Duan LM. Realizing Synthetic Dimensions and Artificial Magnetic Flux in a Trapped-Ion Quantum Simulator. PHYSICAL REVIEW LETTERS 2024; 132:130601. [PMID: 38613306 DOI: 10.1103/physrevlett.132.130601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 12/12/2023] [Accepted: 02/29/2024] [Indexed: 04/14/2024]
Abstract
Synthetic dimension is a potent tool in quantum simulation of topological phases of matter. Here we propose and demonstrate a scheme to simulate an anisotropic Harper-Hofstadter model with controllable magnetic flux on a two-leg ladder using the spin and motional states of a single trapped ion. We verify the successful simulation of this model by comparing the measured dynamics with theoretical predictions under various coupling strength and magnetic flux, and we observe the chiral motion of wave packets on the ladder as evidence of the topological chiral edge modes. We develop a quench path to adiabatically prepare the ground states for varying magnetic flux and coupling strength, and we measure the chiral current on the ladder for the prepared ground states, which allows us to probe the quantum phase transition between the Meissner phase and the vortex phase. Our work demonstrates the trapped ion as a powerful quantum simulation platform for topological quantum matter.
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Affiliation(s)
- Y Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Y-K Wu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- Hefei National Laboratory, Hefei 230088, People's Republic of China
| | - Y Jiang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - M-L Cai
- HYQ Co., Ltd., Beijing 100176, People's Republic of China
| | - B-W Li
- HYQ Co., Ltd., Beijing 100176, People's Republic of China
| | - Q-X Mei
- HYQ Co., Ltd., Beijing 100176, People's Republic of China
| | - B-X Qi
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Z-C Zhou
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- Hefei National Laboratory, Hefei 230088, People's Republic of China
| | - L-M Duan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- Hefei National Laboratory, Hefei 230088, People's Republic of China
- New Cornerstone Science Laboratory, Beijing 100084, People's Republic of China
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6
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Hotter C, Ritsch H, Gietka K. Combining Critical and Quantum Metrology. PHYSICAL REVIEW LETTERS 2024; 132:060801. [PMID: 38394596 DOI: 10.1103/physrevlett.132.060801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 01/16/2024] [Indexed: 02/25/2024]
Abstract
Critical metrology relies on the precise preparation of a system in its ground state near a quantum phase transition point where quantum correlations get very strong. Typically, this increases the quantum Fisher information with respect to changes in system parameters and thus improves the optimally possible measurement precision limited by the Cramér-Rao bound. Hence critical metrology involves encoding information about the unknown parameter in changes of the system's ground state. Conversely, in conventional metrology methods like Ramsey interferometry, the eigenstates of the system remain unchanged, and information about the unknown parameter is encoded in the relative phases that excited system states accumulate during their time evolution. Here we introduce an approach combining these two methodologies into a unified protocol applicable to closed and driven-dissipative systems. We show that the quantum Fisher information in this case exhibits an additional interference term originating from the interplay between eigenstate and relative phase changes. We provide analytical expressions for the quantum and classical Fisher information in such a setup, elucidating as well a straightforward measurement approach that nearly attains the maximum precision permissible under the Cramér-Rao bound. We showcase these results by focusing on the squeezing Hamiltonian, which characterizes the thermodynamic limit of Dicke and Lipkin-Meshkov-Glick Hamiltonians.
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Affiliation(s)
- Christoph Hotter
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Helmut Ritsch
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Karol Gietka
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
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7
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Wang B, Nori F, Xiang ZL. Quantum Phase Transitions in Optomechanical Systems. PHYSICAL REVIEW LETTERS 2024; 132:053601. [PMID: 38364134 DOI: 10.1103/physrevlett.132.053601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 01/03/2024] [Indexed: 02/18/2024]
Abstract
In this Letter, we investigate the ground state properties of an optomechanical system consisting of a coupled cavity and mechanical modes. An exact solution is given when the ratio η between the cavity and mechanical frequencies tends to infinity. This solution reveals a coherent photon occupation in the ground state by breaking continuous or discrete symmetries, exhibiting an equilibrium quantum phase transition (QPT). In the U(1)-broken phase, an unstable Goldstone mode can be excited. In the model featuring Z_{2} symmetry, we discover the mutually (in the finite η) or unidirectionally (in η→∞) dependent relation between the squeezed vacuum of the cavity and mechanical modes. In particular, when the cavity is driven by a squeezed field along the required squeezing parameter, it enables modifying the region of Z_{2}-broken phase and significantly reducing the coupling strength to reach QPTs. Furthermore, by coupling atoms to the cavity mode, the hybrid system can undergo a QPT at a hybrid critical point, which is cooperatively determined by the optomechanical and light-atom systems. These results suggest that this optomechanical system complements other phase transition models for exploring novel critical phenomena.
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Affiliation(s)
- Bo Wang
- School of Physics, Sun Yat-sen University, Guangzhou 510275, China
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama 351-0198, Japan
- Center for Quantum Computing, RIKEN, Wako-shi, Saitama 351-0198, Japan
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA
| | - Ze-Liang Xiang
- School of Physics, Sun Yat-sen University, Guangzhou 510275, China
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8
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Almalki S, Berrada K, Abdel-Khalek S, Eleuch H. Interaction of a four-level atom with a quantized field in the presence of a nonlinear Kerr medium. Sci Rep 2024; 14:1141. [PMID: 38212597 PMCID: PMC10784520 DOI: 10.1038/s41598-024-51649-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 01/08/2024] [Indexed: 01/13/2024] Open
Abstract
Quantum entanglement and atomic coherence are examined for a system consisting of a four-level atom (FLA) interacted with a nonlinear quantum field. We assume that the FLA-field coupling, Kerr medium and quantified field are all [Formula: see text]-deformed with full nonlinear formalism. We consider N-configuration and cascade (C)-configuration of the FLA. We explore the impact of field deformation and Kerr medium on the dynamics of the quantumness measures when the quantized field is initially prepared in a deformed coherent state without and with Kerr medium effect. Moreover, we examine the statistical properties of the radiation field using the second order correlation function. The results indicate how the considered quantumness measures in the FLA-field system can be manipulated and controlled through the parameters of the quantum model.
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Affiliation(s)
- S Almalki
- Department of Physics, Najran University, Najran, Saudi Arabia
| | - K Berrada
- Department of Physics, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, Saudi Arabia.
- The Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste, Italy.
| | - S Abdel-Khalek
- Department of Mathematics and Statistics, College of Science, Taif University, P.O. Box 11099, 21944, Taif, Saudi Arabia
| | - H Eleuch
- Department of Applied Physics and Astronomy, University of Sharjah, 27272, Sharjah, United Arab Emirates
- College of Arts and Sciences, Abu Dhabi University, 59911, Abu Dhabi, United Arab Emirates
- Institute for Quantum Science and Engineering, Texas A&M University, College Station, TX, 77843, USA
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9
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Gietka K, Hotter C, Ritsch H. Unique Steady-State Squeezing in a Driven Quantum Rabi Model. PHYSICAL REVIEW LETTERS 2023; 131:223604. [PMID: 38101370 DOI: 10.1103/physrevlett.131.223604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 11/06/2023] [Indexed: 12/17/2023]
Abstract
Squeezing is essential to many quantum technologies and our understanding of quantum physics. Here, we show a novel type of steady-state squeezing that can be generated in the closed and open quantum Rabi as well as Dicke model. To this end, we eliminate the spin dynamics which effectively leads to an abstract harmonic oscillator whose eigenstates are squeezed with respect to the noninteracting harmonic oscillator. By driving the system, we generate squeezing which has the unique property of time-independent uncertainties and squeezed dynamics. Such squeezing might find applications in continuous backaction evading measurements and should already be observable in optomechanical systems and Coulomb crystals.
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Affiliation(s)
- Karol Gietka
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Christoph Hotter
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
| | - Helmut Ritsch
- Institut für Theoretische Physik, Universität Innsbruck, A-6020 Innsbruck, Austria
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Liu W, Duan L. Quantum Phase Transitions in a Generalized Dicke Model. ENTROPY (BASEL, SWITZERLAND) 2023; 25:1492. [PMID: 37998185 PMCID: PMC10670583 DOI: 10.3390/e25111492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 10/23/2023] [Accepted: 10/27/2023] [Indexed: 11/25/2023]
Abstract
We investigate a generalized Dicke model by introducing two interacting spin ensembles coupled with a single-mode bosonic field. Apart from the normal to superradiant phase transition induced by the strong spin-boson coupling, interactions between the two spin ensembles enrich the phase diagram by introducing ferromagnetic, antiferromagnetic and paramagnetic phases. The mean-field approach reveals a phase diagram comprising three phases: paramagnetic-normal phase, ferromagnetic-superradiant phase, and antiferromagnetic-normal phase. Ferromagnetic spin-spin interaction can significantly reduce the required spin-boson coupling strength to observe the superradiant phase, where the macroscopic excitation of the bosonic field occurs. Conversely, antiferromagnetic spin-spin interaction can strongly suppress the superradiant phase. To examine higher-order quantum effects beyond the mean-field contribution, we utilize the Holstein-Primakoff transformation, which converts the generalized Dicke model into three coupled harmonic oscillators in the thermodynamic limit. Near the critical point, we observe the close of the energy gap between the ground and the first excited states, the divergence of entanglement entropy and quantum fluctuation in certain quadrature. These observations further confirm the quantum phase transition and offer additional insights into critical behaviors.
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Affiliation(s)
- Wen Liu
- Key Laboratory of Optical Information Detecting and Display Technology of Zhejiang, Zhejiang Normal University, Jinhua 321004, China;
| | - Liwei Duan
- Department of Physics, Zhejiang Normal University, Jinhua 321004, China
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11
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Zheng RH, Ning W, Chen YH, Lü JH, Shen LT, Xu K, Zhang YR, Xu D, Li H, Xia Y, Wu F, Yang ZB, Miranowicz A, Lambert N, Zheng D, Fan H, Nori F, Zheng SB. Observation of a Superradiant Phase Transition with Emergent Cat States. PHYSICAL REVIEW LETTERS 2023; 131:113601. [PMID: 37774281 DOI: 10.1103/physrevlett.131.113601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/29/2023] [Accepted: 08/10/2023] [Indexed: 10/01/2023]
Abstract
Superradiant phase transitions (SPTs) are important for understanding light-matter interactions at the quantum level, and play a central role in criticality-enhanced quantum sensing. So far, SPTs have been observed in driven-dissipative systems, but the emergent light fields did not show any nonclassical characteristic due to the presence of strong dissipation. Here we report an experimental demonstration of the SPT featuring the emergence of a highly nonclassical photonic field, realized with a resonator coupled to a superconducting qubit, implementing the quantum Rabi model. We fully characterize the light-matter state by Wigner matrix tomography. The measured matrix elements exhibit quantum interference intrinsic of a photonic mesoscopic superposition, and reveal light-matter entanglement.
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Affiliation(s)
- Ri-Hua Zheng
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Wen Ning
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Ye-Hong Chen
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
- Quantum Information Physics Theory Research Team, RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama 351-0198, Japan
| | - Jia-Hao Lü
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Li-Tuo Shen
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Kai Xu
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yu-Ran Zhang
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
- Quantum Information Physics Theory Research Team, RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama 351-0198, Japan
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou 510640, China
| | - Da Xu
- Interdisciplinary Center of Quantum Information, State Key Laboratory of Modern Optical Instrumentation and Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou 310027, China
| | - Hekang Li
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Yan Xia
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Fan Wu
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Zhen-Biao Yang
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Adam Miranowicz
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
- Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań, Poland
| | - Neill Lambert
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
| | - Dongning Zheng
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Heng Fan
- Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, RIKEN Cluster for Pioneering Research, Wako-shi, Saitama 351-0198, Japan
- Quantum Information Physics Theory Research Team, RIKEN Center for Quantum Computing (RQC), Wako-shi, Saitama 351-0198, Japan
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA
| | - Shi-Biao Zheng
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
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12
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Zeng Y, Zhou ZY, Rinaldi E, Gneiting C, Nori F. Approximate Autonomous Quantum Error Correction with Reinforcement Learning. PHYSICAL REVIEW LETTERS 2023; 131:050601. [PMID: 37595216 DOI: 10.1103/physrevlett.131.050601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 06/22/2023] [Indexed: 08/20/2023]
Abstract
Autonomous quantum error correction (AQEC) protects logical qubits by engineered dissipation and thus circumvents the necessity of frequent, error-prone measurement-feedback loops. Bosonic code spaces, where single-photon loss represents the dominant source of error, are promising candidates for AQEC due to their flexibility and controllability. While existing proposals have demonstrated the in-principle feasibility of AQEC with bosonic code spaces, these schemes are typically based on the exact implementation of the Knill-Laflamme conditions and thus require the realization of Hamiltonian distances d≥2. Implementing such Hamiltonian distances requires multiple nonlinear interactions and control fields, rendering these schemes experimentally challenging. Here, we propose a bosonic code for approximate AQEC by relaxing the Knill-Laflamme conditions. Using reinforcement learning (RL), we identify the optimal bosonic set of code words (denoted here by RL code), which, surprisingly, is composed of the Fock states |2⟩ and |4⟩. As we show, the RL code, despite its approximate nature, successfully suppresses single-photon loss, reducing it to an effective dephasing process that well surpasses the break-even threshold. It may thus provide a valuable building block toward full error protection. The error-correcting Hamiltonian, which includes ancilla systems that emulate the engineered dissipation, is entirely based on the Hamiltonian distance d=1, significantly reducing model complexity. Single-qubit gates are implemented in the RL code with a maximum distance d_{g}=2.
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Affiliation(s)
- Yexiong Zeng
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Quantum Computing Center, RIKEN, Wakoshi, Saitama 351-0198, Japan
| | - Zheng-Yang Zhou
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
| | - Enrico Rinaldi
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Quantum Computing Center, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Quantinuum K.K., Otemachi Financial City Grand Cube 3F, 1-9-2 Otemachi, Chiyoda-ku, Tokyo, Japan
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA
- Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), RIKEN, Wakoshi, Saitama 351-0198, Japan
| | - Clemens Gneiting
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Quantum Computing Center, RIKEN, Wakoshi, Saitama 351-0198, Japan
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Quantum Computing Center, RIKEN, Wakoshi, Saitama 351-0198, Japan
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040, USA
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13
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De Filippis G, de Candia A, Di Bello G, Perroni CA, Cangemi LM, Nocera A, Sassetti M, Fazio R, Cataudella V. Signatures of Dissipation Driven Quantum Phase Transition in Rabi Model. PHYSICAL REVIEW LETTERS 2023; 130:210404. [PMID: 37295090 DOI: 10.1103/physrevlett.130.210404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 04/13/2023] [Indexed: 06/12/2023]
Abstract
By using the worldline Monte Carlo technique, matrix product state, and a variational approach à la Feynman, we investigate the equilibrium properties and relaxation features of the dissipative quantum Rabi model, where a two level system is coupled to a linear harmonic oscillator embedded in a viscous fluid. We show that, in the Ohmic regime, a Beretzinski-Kosterlitz-Thouless quantum phase transition occurs by varying the coupling strength between the two level system and the oscillator. This is a nonperturbative result, occurring even for extremely low dissipation magnitude. By using state-of-the-art theoretical methods, we unveil the features of the relaxation towards the thermodynamic equilibrium, pointing out the signatures of quantum phase transition both in the time and frequency domains. We prove that, for low and moderate values of the dissipation, the quantum phase transition occurs in the deep strong coupling regime. We propose to realize this model by coupling a flux qubit and a damped LC oscillator.
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Affiliation(s)
- G De Filippis
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
- INFN, Sezione di Napoli-Complesso Universitario di Monte S. Angelo-I-80126 Napoli, Italy
| | - A de Candia
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
- INFN, Sezione di Napoli-Complesso Universitario di Monte S. Angelo-I-80126 Napoli, Italy
| | - G Di Bello
- Dipartimento di Fisica Ettore Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
| | - C A Perroni
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
| | - L M Cangemi
- Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - A Nocera
- Department of Physics and Astronomy and Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z1
| | - M Sassetti
- Dipartimento di Fisica, Università di Genova, I-16146 Genova, Italy
- SPIN-CNR, I-16146 Genova, Italy
| | - R Fazio
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
- ICTP, Strada Costiera 11, I-34151 Trieste, Italy
- NEST, Istituto Nanoscienze-CNR, I-56126 Pisa, Italy
| | - V Cataudella
- SPIN-CNR and Dip. di Fisica E. Pancini-Università di Napoli Federico II-I-80126 Napoli, Italy
- INFN, Sezione di Napoli-Complesso Universitario di Monte S. Angelo-I-80126 Napoli, Italy
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14
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Koch J, Hunanyan GR, Ockenfels T, Rico E, Solano E, Weitz M. Quantum Rabi dynamics of trapped atoms far in the deep strong coupling regime. Nat Commun 2023; 14:954. [PMID: 36808135 PMCID: PMC9941496 DOI: 10.1038/s41467-023-36611-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 02/09/2023] [Indexed: 02/22/2023] Open
Abstract
The coupling of a two-level system with an electromagnetic field, whose fully quantized version is the quantum Rabi model, is among the central topics of quantum physics. When the coupling strength becomes large enough that the field mode frequency is reached, the deep strong coupling regime is approached, and excitations can be created from the vacuum. Here we demonstrate a periodic variant of the quantum Rabi model in which the two-level system is encoded in the Bloch band structure of cold rubidium atoms in optical potentials. With this method we achieve a Rabi coupling strength of 6.5 times the field mode frequency, which is far in the deep strong coupling regime, and observe a subcycle timescale raise in bosonic field mode excitations. In a measurement recorded in the basis of the coupling term of the quantum Rabi Hamiltonian, a freezing of dynamics is revealed for small frequency splittings of the two-level system, as expected when the coupling term dominates over all other energy scales, and a revival for larger splittings. Our work demonstrates a route to realize quantum-engineering applications in yet unexplored parameter regimes.
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Affiliation(s)
- Johannes Koch
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115, Bonn, Germany.
| | - Geram R. Hunanyan
- grid.10388.320000 0001 2240 3300Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany
| | - Till Ockenfels
- grid.10388.320000 0001 2240 3300Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany
| | - Enrique Rico
- grid.11480.3c0000000121671098EHU Quantum Center, University of the Basque Country UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain ,grid.11480.3c0000000121671098Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain ,grid.424810.b0000 0004 0467 2314IKERBASQUE, Basque Foundation for Science, Plaza Euskadi 5, 48009 Bilbao, Spain
| | - Enrique Solano
- grid.11480.3c0000000121671098Department of Physical Chemistry, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain ,grid.424810.b0000 0004 0467 2314IKERBASQUE, Basque Foundation for Science, Plaza Euskadi 5, 48009 Bilbao, Spain ,Kipu Quantum, Greifswalder Straße 226, 10405 Berlin, Germany ,grid.39436.3b0000 0001 2323 5732International Center of Quantum Artificial Intelligence for Science and Technology (QuArtist) and Department of Physics, Shanghai University, 200444 Shanghai, China
| | - Martin Weitz
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115, Bonn, Germany.
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15
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Li BW, Mei QX, Wu YK, Cai ML, Wang Y, Yao L, Zhou ZC, Duan LM. Observation of Non-Markovian Spin Dynamics in a Jaynes-Cummings-Hubbard Model Using a Trapped-Ion Quantum Simulator. PHYSICAL REVIEW LETTERS 2022; 129:140501. [PMID: 36240415 DOI: 10.1103/physrevlett.129.140501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
The Jaynes-Cummings-Hubbard (JCH) model is a fundamental many-body model for light-matter interaction. As a leading platform for quantum simulation, the trapped ion system has realized the JCH model for two to three ions. Here, we report the quantum simulation of the JCH model using up to 32 ions. We verify the simulation results even for large ion numbers by engineering low excitations and thus low effective dimensions; then we extend to 32 excitations for an effective dimension of 2^{77}, which is difficult for classical computers. By regarding the phonon modes as baths, we explore Markovian or non-Markovian spin dynamics in different parameter regimes of the JCH model, similar to quantum emitters in a structured photonic environment. We further examine the dependence of the non-Markovian dynamics on the effective Hilbert space dimension. Our Letter demonstrates the trapped ion system as a powerful quantum simulator for many-body physics and open quantum systems.
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Affiliation(s)
- B-W Li
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Q-X Mei
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Y-K Wu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - M-L Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- HYQ Co., Ltd., Beijing, 100176, People's Republic of China
| | - Y Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - L Yao
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- HYQ Co., Ltd., Beijing, 100176, People's Republic of China
| | - Z-C Zhou
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - L-M Duan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
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16
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Li RR, He R, Cui JM, Chen Y, Ye WR, Chen YL, Huang YF, Li CF, Guo GC. A versatile multi-tone laser system for manipulating atomic qubits based on a fiber Mach-Zehnder modulator and second harmonic generation. OPTICS EXPRESS 2022; 30:30098-30107. [PMID: 36242120 DOI: 10.1364/oe.462737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 07/19/2022] [Indexed: 06/16/2023]
Abstract
Stimulated Raman transition is a fundamental method to coherently manipulate quantum states in different physical systems. Phase-coherent dichromatic radiation fields matching the energy level splitting are the key to realizing stimulated Raman transition. Here we demonstrate a flexible-tuning, spectrum-clean and fiber-compatible method to generate a highly phase-coherent and high-power multi-tone laser. This method features the utilization of a broadband fiber Mach-Zehnder modulator working at carrier suppression condition and second harmonic generation. We generate a multi-tone continuous-wave 532 nm laser with a power of 1.5 Watts and utilize it to manipulate the spin and motional states of a trapped 171Yb+ ion via stimulated Raman transition. For spin state manipulation, we acquire an effective Rabi frequency of 2π × 662.3 kHz. Due to the broad bandwidth of the fiber modulator and nonlinear crystal, the frequency gap between tones can be flexibly tuned. Benefiting from the features above, this method can manipulate 171Yb+ and 137Ba+ simultaneously in the multi-species ion trap and has potential to be widely applied in atomic, molecular and optical physics.
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17
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Podhora L, Lachman L, Pham T, Lešundák A, Číp O, Slodička L, Filip R. Quantum Non-Gaussianity of Multiphonon States of a Single Atom. PHYSICAL REVIEW LETTERS 2022; 129:013602. [PMID: 35841581 DOI: 10.1103/physrevlett.129.013602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 03/22/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Quantum non-Gaussian mechanical states are already required in a range of applications. The discrete building blocks of such states are the energy eigenstates-Fock states. Despite progress in their preparation, the remaining imperfections can still invisibly cause loss of the aspects critical for their applications. We derive and apply the most challenging hierarchy of quantum non-Gaussian criteria on the characterization of single trapped-ion oscillator mechanical Fock states with up to 10 phonons. We analyze the depth of these quantum non-Gaussian features under intrinsic mechanical heating and predict their requirement for reaching quantum advantage in the sensing of a mechanical force.
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Affiliation(s)
- L Podhora
- Department of Optics, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic
| | - L Lachman
- Department of Optics, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic
| | - T Pham
- Institute of Scientific Instruments of the Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - A Lešundák
- Institute of Scientific Instruments of the Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - O Číp
- Institute of Scientific Instruments of the Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - L Slodička
- Department of Optics, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic
| | - R Filip
- Department of Optics, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic
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18
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Cai ML, Wu YK, Mei QX, Zhao WD, Jiang Y, Yao L, He L, Zhou ZC, Duan LM. Observation of supersymmetry and its spontaneous breaking in a trapped ion quantum simulator. Nat Commun 2022; 13:3412. [PMID: 35701410 PMCID: PMC9197856 DOI: 10.1038/s41467-022-31058-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 05/23/2022] [Indexed: 11/09/2022] Open
Abstract
Supersymmetry (SUSY) helps solve the hierarchy problem in high-energy physics and provides a natural groundwork for unifying gravity with other fundamental interactions. While being one of the most promising frameworks for theories beyond the Standard Model, its direct experimental evidence in nature still remains to be discovered. Here we report experimental realization of a supersymmetric quantum mechanics (SUSY QM) model, a reduction of the SUSY quantum field theory for studying its fundamental properties, using a trapped ion quantum simulator. We demonstrate the energy degeneracy caused by SUSY in this model and the spontaneous SUSY breaking. By a partial quantum state tomography of the spin-phonon coupled system, we explicitly measure the supercharge of the degenerate ground states, which are superpositions of the bosonic and the fermionic states. Our work demonstrates the trapped-ion quantum simulator as an economic yet powerful platform to study versatile physics in a single well-controlled system.
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Affiliation(s)
- M-L Cai
- Center for Quantumf Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, People's Republic of China
- HYQ Co., Ltd, 100176, Beijing, People's Republic of China
| | - Y-K Wu
- Center for Quantumf Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, People's Republic of China
| | - Q-X Mei
- Center for Quantumf Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, People's Republic of China
| | - W-D Zhao
- Center for Quantumf Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, People's Republic of China
| | - Y Jiang
- Center for Quantumf Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, People's Republic of China
| | - L Yao
- Center for Quantumf Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, People's Republic of China
- HYQ Co., Ltd, 100176, Beijing, People's Republic of China
| | - L He
- Center for Quantumf Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, People's Republic of China
| | - Z-C Zhou
- Center for Quantumf Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, People's Republic of China
- Beijing Academy of Quantum Information Sciences, 100193, Beijing, People's Republic of China
| | - L-M Duan
- Center for Quantumf Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, 100084, Beijing, People's Republic of China.
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19
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Jiang Y, Cai ML, Wu YK, Mei QX, Zhao WD, Chang XY, Yao L, He L, Zhou ZC, Duan LM. Quantum Simulation of the Two-Dimensional Weyl Equation in a Magnetic Field. PHYSICAL REVIEW LETTERS 2022; 128:200502. [PMID: 35657866 DOI: 10.1103/physrevlett.128.200502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/25/2022] [Indexed: 06/15/2023]
Abstract
Quantum simulation of 1D relativistic quantum mechanics has been achieved in well-controlled systems like trapped ions, but properties like spin dynamics and response to external magnetic fields that appear only in higher dimensions remain unexplored. Here we simulate the dynamics of a 2D Weyl particle. We show the linear dispersion relation of the free particle and the discrete Landau levels in a magnetic field, and we explicitly measure the spatial and spin dynamics from which the conservation of helicity and properties of antiparticles can be verified. Our work extends the application of an ion trap quantum simulator in particle physics with the additional spatial and spin degrees of freedom.
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Affiliation(s)
- Y Jiang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - M-L Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- HYQ Co., Ltd., Beijing 100176, People's Republic of China
| | - Y-K Wu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Q-X Mei
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - W-D Zhao
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - X-Y Chang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - L Yao
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- HYQ Co., Ltd., Beijing 100176, People's Republic of China
| | - L He
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Z-C Zhou
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - L-M Duan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
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20
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de Sá Neto OP, Costa HAS, Prataviera GA, de Oliveira MC. Temperature estimation of a pair of trapped ions. Sci Rep 2022; 12:6697. [PMID: 35461351 PMCID: PMC9035191 DOI: 10.1038/s41598-022-10572-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 04/01/2022] [Indexed: 11/17/2022] Open
Abstract
We apply estimation theory to a system formed by two interacting trapped ions. By using the Fisher matrix formalism, we introduce a simple scheme for estimation of the temperature of the longitudinal vibrational modes of the ions. We use the ions interaction to effectively infer the temperature of the individual ions, by optimising the interaction time evolution and by measuring only over one of the ions. We also investigate the effect of a non-thermal reservoir over the inference approach. The non-classicality of one of the ions vibrational modes, introduced due to a squeezed thermal reservoir, does not directly affect the inference of the individual temperatures, although allowing the modes to be entangled. To check actual experimental conditions, we analyze the temperature inference under heating due to surface-electrode noise.
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Affiliation(s)
- O P de Sá Neto
- Coordenação de Ciência da Computação, Universidade Estadual do Piauí, Parnaíba, PI, 64202-220, Brazil
| | - H A S Costa
- Departamento de Física, Universidade Federal do Piauí, Teresina, PI, 64049-550, Brazil
| | - G A Prataviera
- Departamento de Administração, FEA-RP, Universidade de São Paulo, Ribeirão Preto, SP, 14040-905, Brazil
| | - M C de Oliveira
- Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Campinas, SP, 13083-970, Brazil.
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21
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Mei QX, Li BW, Wu YK, Cai ML, Wang Y, Yao L, Zhou ZC, Duan LM. Experimental Realization of the Rabi-Hubbard Model with Trapped Ions. PHYSICAL REVIEW LETTERS 2022; 128:160504. [PMID: 35522503 DOI: 10.1103/physrevlett.128.160504] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/26/2022] [Accepted: 03/31/2022] [Indexed: 06/14/2023]
Abstract
Quantum simulation provides important tools in studying strongly correlated many-body systems with controllable parameters. As a hybrid of two fundamental models in quantum optics and in condensed matter physics, the Rabi-Hubbard model demonstrates rich physics through the competition between local spin-boson interactions and long-range boson hopping. Here, we report an experimental realization of the Rabi-Hubbard model using up to 16 trapped ions and present a controlled study of its equilibrium properties and quantum dynamics. We observe the ground-state quantum phase transition by slowly quenching the coupling strength, and measure the quantum dynamical evolution in various parameter regimes. With the magnetization and the spin-spin correlation as probes, we verify the prediction of the model Hamiltonian by comparing theoretical results in small system sizes with experimental observations. For larger-size systems of 16 ions and 16 phonon modes, the effective Hilbert space dimension exceeds 2^{57}, whose dynamics is intractable for classical supercomputers.
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Affiliation(s)
- Q-X Mei
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - B-W Li
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Y-K Wu
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - M-L Cai
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- HYQ Co., Ltd., Beijing, 100176, People's Republic of China
| | - Y Wang
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - L Yao
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
- HYQ Co., Ltd., Beijing, 100176, People's Republic of China
| | - Z-C Zhou
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - L-M Duan
- Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084, People's Republic of China
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22
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Zhao J, Hwang MJ. Frustrated Superradiant Phase Transition. PHYSICAL REVIEW LETTERS 2022; 128:163601. [PMID: 35522483 DOI: 10.1103/physrevlett.128.163601] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/08/2022] [Indexed: 06/14/2023]
Abstract
Frustration occurs when a system cannot find a lowest-energy configuration due to conflicting constraints. We show that a frustrated superradiant phase transition occurs when the ground-state superradiance of cavity fields due to local light-matter interactions cannot simultaneously minimize the positive photon hopping energies. We solve the Dicke trimer model on a triangle motif with both negative and positive hopping energies and show that the latter results in a sixfold degenerate ground-state manifold in which the translational symmetry is spontaneously broken. In the frustrated superradiant phase, we find that two sets of diverging time and fluctuation scales coexist, one governed by the mean-field critical exponent and another by a novel critical exponent. The latter is associated with the fluctuation in the difference of local order parameters and gives rise to site-dependent photon number critical exponents, which may serve as an experimental probe for the frustrated superradiant phase. We provide a qualitative explanation for the emergence of unconventional critical scalings and demonstrate that they are generic properties of the frustrated superradiant phase at the hand of a one-dimensional Dicke lattice with an odd number of sites. The mechanism for the frustrated superradiant phase transition discovered here applies to any lattice geometries where the antiferromagnetic ordering of neighboring sites are incompatible and therefore our work paves the way toward the exploration of frustrated phases of coupled light and matter.
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Affiliation(s)
- Jinchen Zhao
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu 215300, China
| | - Myung-Joong Hwang
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu 215300, China
- Zu Chongzhi Center for Mathematics and Computational Science, Duke Kunshan University, Kunshan, Jiangsu 215300, China
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23
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Laha P, Slodička L, Moore DW, Filip R. Thermally induced entanglement of atomic oscillators. OPTICS EXPRESS 2022; 30:8814-8828. [PMID: 35299326 DOI: 10.1364/oe.449811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Abstract
Laser cooled ions trapped in a linear Paul trap are long-standing ideal candidates for realizing quantum simulation, especially of many-body systems. The properties that contribute to this also provide the opportunity to demonstrate unexpected quantum phenomena in few-body systems. A pair of ions interacting in such traps exchange vibrational quanta through the Coulomb interaction. This linear interaction can be anharmonically modulated by an elementary coupling to the internal two-level structure of one of the ions. Driven by thermal energy in the passively coupled oscillators, which are themselves coupled to the internal ground states of the ions, the nonlinear interaction autonomously and unconditionally generates entanglement between the mechanical modes of the ions. We examine this counter-intuitive thermally induced entanglement for several experimentally feasible model systems and propose parameter regimes where state-of-the-art trapped ion systems can produce such phenomena. In addition, we demonstrate a multiqubit enhancement of such thermally induced entanglements.
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24
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Chen X, Wu Z, Jiang M, Lü XY, Peng X, Du J. Experimental quantum simulation of superradiant phase transition beyond no-go theorem via antisqueezing. Nat Commun 2021; 12:6281. [PMID: 34725347 PMCID: PMC8560888 DOI: 10.1038/s41467-021-26573-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 09/24/2021] [Indexed: 11/09/2022] Open
Abstract
The superradiant phase transition in thermal equilibrium is a fundamental concept bridging statistical physics and electrodynamics, which has never been observed in real physical systems since the first proposal in the 1970s. The existence of this phase transition in cavity quantum electrodynamics systems is still subject of ongoing debates due to the no-go theorem induced by the so-called A2 term. Moreover, experimental conditions to study this phase transition are hard to achieve with current accessible technology. Based on the platform of nuclear magnetic resonance, here we experimentally simulate the occurrence of an equilibrium superradiant phase transition beyond no-go theorem by introducing the antisqueezing effect. The mechanism relies on that the antisqueezing effect recovers the singularity of the ground state via exponentially enhancing the zero point fluctuation of system. The strongly entangled and squeezed Schrödinger cat states of spins are achieved experimentally in the superradiant phase, which may play an important role in fundamental tests of quantum theory and implementations of quantum metrology. Quantum simulation allows to investigate otherwise inaccessible physical scenarios. Here, the authors simulate a quantum Rabi model using nuclear spins, including the A2 term and an anti-squeezing term, which allows them to see signatures of a superradiant phase transition in the simulated system.
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Affiliation(s)
- Xi Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, 230026, China.,CAS Key Laboratory of Microscale Magnetic Resonance, University of Science and Technology of China, Hefei, 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Ze Wu
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, 230026, China.,CAS Key Laboratory of Microscale Magnetic Resonance, University of Science and Technology of China, Hefei, 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Min Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, 230026, China.,CAS Key Laboratory of Microscale Magnetic Resonance, University of Science and Technology of China, Hefei, 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, China
| | - Xin-You Lü
- School of physics, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Xinhua Peng
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, 230026, China. .,CAS Key Laboratory of Microscale Magnetic Resonance, University of Science and Technology of China, Hefei, 230026, China. .,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, China.
| | - Jiangfeng Du
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, 230026, China.,CAS Key Laboratory of Microscale Magnetic Resonance, University of Science and Technology of China, Hefei, 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, 230026, China
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25
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Enhanced Parameter Estimation with Periodically Driven Quantum Probe. ENTROPY 2021; 23:e23101333. [PMID: 34682057 PMCID: PMC8534368 DOI: 10.3390/e23101333] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 10/07/2021] [Accepted: 10/08/2021] [Indexed: 11/26/2022]
Abstract
I propose a quantum metrology protocol for measuring frequencies and weak forces based on a periodic modulating quantum Jahn–Teller system composed of a single spin and two bosonic modes. I show that, in the first order of the frequency drive, the time-independent effective Hamiltonian describes spin-dependent interaction between the two bosonic modes. In the limit of high-frequency drive and low bosonic frequency, the quantum Jahn–Teller system exhibits critical behavior which can be used for high-precision quantum estimation. A major advantage of the scheme is the robustness of the system against spin decoherence, which allows it to perform parameter estimation with measurement time not limited by spin dephasing.
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26
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Corps ÁL, Relaño A. Constant of Motion Identifying Excited-State Quantum Phases. PHYSICAL REVIEW LETTERS 2021; 127:130602. [PMID: 34623829 DOI: 10.1103/physrevlett.127.130602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/26/2021] [Accepted: 09/03/2021] [Indexed: 06/13/2023]
Abstract
We propose that a broad class of excited-state quantum phase transitions (ESQPTs) gives rise to two different excited-state quantum phases. These phases are identified by means of an operator C[over ^], which is a constant of motion in only one of them. Hence, the ESQPT critical energy splits the spectrum into one phase where the equilibrium expectation values of physical observables crucially depend on this constant of motion and another phase where the energy is the only relevant thermodynamic magnitude. The trademark feature of this operator is that it has two different eigenvalues ±1, and, therefore, it acts as a discrete symmetry in the first of these two phases. This scenario is observed in systems with and without an additional discrete symmetry; in the first case, C[over ^] explains the change from degenerate doublets to nondegenerate eigenlevels upon crossing the critical line. We present stringent numerical evidence in the Rabi and Dicke models, suggesting that this result is exact in the thermodynamic limit, with finite-size corrections that decrease as a power law.
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Affiliation(s)
- Ángel L Corps
- Departamento de Estructura de la Materia, Física Térmica y Electrónica and Grupo Interdisciplinar de Sistemas Complejos (GISC), Universidad Complutense de Madrid, Avenida Complutense s/n, E-28040 Madrid, Spain
| | - Armando Relaño
- Departamento de Estructura de la Materia, Física Térmica y Electrónica and Grupo Interdisciplinar de Sistemas Complejos (GISC), Universidad Complutense de Madrid, Avenida Complutense s/n, E-28040 Madrid, Spain
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27
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Zhang YY, Hu ZX, Fu L, Luo HG, Pu H, Zhang XF. Quantum Phases in a Quantum Rabi Triangle. PHYSICAL REVIEW LETTERS 2021; 127:063602. [PMID: 34420322 DOI: 10.1103/physrevlett.127.063602] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 06/30/2021] [Indexed: 06/13/2023]
Abstract
The interplay of interactions, symmetries, and gauge fields usually leads to intriguing quantum many-body phases. To explore the nature of emerging phases, we study a quantum Rabi triangle system as an elementary building block for synthesizing an artificial magnetic field. We develop an analytical approach to study the rich phase diagram and the associated quantum criticality. Of particular interest is the emergence of a chiral-coherent phase, which breaks both the Z_{2} and the chiral symmetry. In this chiral phase, photons flow unidirectionally and the chirality can be tuned by the artificial gauge field, exhibiting a signature of broken time-reversal symmetry. The finite-frequency scaling analysis further confirms the associated phase transition to be in the universality class of the Dicke model. This model can simulate a broad range of physical phenomena of light-matter coupling systems, and may have an application in future developments of various quantum information technologies.
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Affiliation(s)
- Yu-Yu Zhang
- Department of Physics, Chongqing University, Chongqing 401330, China
- Chongqing Key Laboratory for strongly coupled Physics, Chongqing 401331, China
| | - Zi-Xiang Hu
- Department of Physics, Chongqing University, Chongqing 401330, China
- Chongqing Key Laboratory for strongly coupled Physics, Chongqing 401331, China
| | - Libin Fu
- Graduate School, China Academy of Engineering Physics, Beijing 100193, China
| | - Hong-Gang Luo
- School of Physical Science and Technology, Lanzhou University, Lanzhou 730000, China
| | - Han Pu
- Department of Physics and Astronomy, and Rice Center for Quantum Materials, Rice University, Houston, Texas 77251-1892, USA
| | - Xue-Feng Zhang
- Department of Physics, Chongqing University, Chongqing 401330, China
- Department of Physics, and Center of Quantum Materials and Devices, Chongqing University, Chongqing 401331, China
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