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学者姓名：吴凡
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Abstract ：
Dissipation usually plays a negative role in quantum metrological technologies, which aim to improve measurement precision by leveraging quantum effects that are vulnerable to environment-induced decoherence. Recently, it has been demonstrated that dissipation can actually be used as a favorable resource for enhancing the susceptibility of signal detection. However, demonstrations of such enhancement for detecting physical quantities in open quantum systems are still lacking. Here a protocol is proposed and demonstrated for realizing such non-Hermitian quantum sensors for probing the coupling between a qubit and a resonator subjecting to energy dissipations. The excitation-number conversion associated with the no-jump evolution trajectory enables removal of the noisy outcomes with quantum jumps, implementing the exceptional point (EP), where the Rabi splitting exhibits a divergent behavior in response to a tiny variation of the effective coupling. The sensitivity enhancement near the EP is confirmed by both theoretical calculation and experimental measurement.
Keyword ：
exceptional point exceptional point quantum sensing quantum sensing superconducting circuit superconducting circuit
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| GB/T 7714 | Han, Pei-Rong , Wu, Fan , Huang, Xin-Jie et al. Enhancement of Sensitivity Near Exceptional Points in Dissipative Qubit-Resonator Systems [J]. | ADVANCED QUANTUM TECHNOLOGIES , 2025 . |
| MLA | Han, Pei-Rong et al. "Enhancement of Sensitivity Near Exceptional Points in Dissipative Qubit-Resonator Systems" . | ADVANCED QUANTUM TECHNOLOGIES (2025) . |
| APA | Han, Pei-Rong , Wu, Fan , Huang, Xin-Jie , Wu, Huai-Zhi , Zou, Chang-Ling , Yi, Wei et al. Enhancement of Sensitivity Near Exceptional Points in Dissipative Qubit-Resonator Systems . | ADVANCED QUANTUM TECHNOLOGIES , 2025 . |
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We study the dynamic generation of persistent current by phase imprinting fermionic atoms in a ring geometry at zero temperature. Mediated by the pairing interaction, the Fermi condensate dynamically acquires a quantized current by developing azimuthal phase slips, as well as density and pairing-order-parameter depletions. Resorting to the Bogolioubov-de Gennes formalism, we investigate the time evolution of the transferred total angular momentum and the quantized superfluid current throughout the phase-imprinting process. This enables a detailed self-consistent analysis of the impact of interaction, as well as different initial pairing states, on the superflow formation, in contrast to previous theoretical analysis based on the Gross-Pitaevskii equation with artificially imposed phases. In particular, we show that, as the interaction strength increases, the azimuthal density distribution becomes less susceptible to the phase imprinting potential, leading to a smaller quantized current under the same imprinting parameters. Our results offer microscopic insights into the dynamic development of superflow in the phase-imprinting process, and are helpful for the ongoing experimental effort. © 2025 authors. Published by the American Physical Society.
Keyword ：
Angular momentum Angular momentum Fermions Fermions Supersonic flow Supersonic flow
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| GB/T 7714 | Chen, Ke-Ji , Yi, Wei , Wu, Fan . Dynamic generation of superflow in a fermionic ring through phase imprinting [J]. | Physical Review Research , 2025 , 7 (1) . |
| MLA | Chen, Ke-Ji et al. "Dynamic generation of superflow in a fermionic ring through phase imprinting" . | Physical Review Research 7 . 1 (2025) . |
| APA | Chen, Ke-Ji , Yi, Wei , Wu, Fan . Dynamic generation of superflow in a fermionic ring through phase imprinting . | Physical Review Research , 2025 , 7 (1) . |
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Spontaneous symmetry breaking (SSB) is crucial to the occurrence of phase transitions. Once a phase transition occurs, a quantum system presents degenerate eigenstates that lack the symmetry of the Hamiltonian. After crossing the critical point, the system is essentially evolved to a quantum superposition of these eigenstates until decoherence sets in. Despite the fundamental importance and potential applications in quantum technologies, such quantum-mechanical SSB phenomena have not been experimentally explored in many-body systems. We here present an experimental demonstration of the SSB process in the Lipkin-Meshkov-Glick model, governed by the competition between the individual driving and intraqubit interaction. The model is realized in a circuit quantum electrodynamics system, where 6 Xmon qubits are coupled in an all-to-all manner through virtual photon exchange mediated by a resonator. The observed nonclassical correlations among these qubits in the symmetry-breaking region go beyond the conventional description of SSB, shedding new light on phase transitions for quantum many-body systems. © 2025 American Physical Society.
Keyword ：
Quantum channel Quantum channel Quantum electronics Quantum electronics Quantum entanglement Quantum entanglement Quantum optics Quantum optics Qubits Qubits
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| GB/T 7714 | Zheng, Ri-Hua , Ning, Wen , Lü, Jia-Hao et al. Experimental Demonstration of Spontaneous Symmetry Breaking with Emergent Multiqubit Entanglement [J]. | Physical Review Letters , 2025 , 134 (15) . |
| MLA | Zheng, Ri-Hua et al. "Experimental Demonstration of Spontaneous Symmetry Breaking with Emergent Multiqubit Entanglement" . | Physical Review Letters 134 . 15 (2025) . |
| APA | Zheng, Ri-Hua , Ning, Wen , Lü, Jia-Hao , Yu, Xue-Jia , Wu, Fan , Deng, Cheng-Lin et al. Experimental Demonstration of Spontaneous Symmetry Breaking with Emergent Multiqubit Entanglement . | Physical Review Letters , 2025 , 134 (15) . |
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Owing to the presence of exceptional points (EPs), non-Hermitian (NH) systems can display intriguing topological phenomena without Hermitian analogs. However, experimental characterizations of exceptional topological invariants have been restricted to second-order EPs (EP2s) in classical or semiclassical systems. We here propose an NH multi-mode system with higher-order EPs, each of which is underlain by a multifold-degenerate multipartite entangled eigenstate. We implement the NH model by controllably coupling a Josephson-junction-based electronic mode to two microwave resonators. We experimentally quantify the topological invariant for an EP3, by mapping out the complex eigenspectra of the tripartite system along a loop surrounding this EP3 in the parameter space. The nonclassicality of the realized topology is manifested by the observed quantum correlations in the corresponding eigenstates. Our results extend research of exceptional topology to fully quantum-mechanical models with multipartite entangled eigenstates. Exceptional topology associated with higher-order exceptional points has not been completely characterised in quantum systems. Here, the authors fill this gap performing full quantum state tomography in a system composed of a superconducting qubit coupled to two cavities, one lossless and one lossy, featuring third-order exceptional points.
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| GB/T 7714 | Han, Pei-Rong , Ning, Wen , Huang, Xin-Jie et al. Measuring topological invariants for higher-order exceptional points in quantum three-mode systems [J]. | NATURE COMMUNICATIONS , 2024 , 15 (1) . |
| MLA | Han, Pei-Rong et al. "Measuring topological invariants for higher-order exceptional points in quantum three-mode systems" . | NATURE COMMUNICATIONS 15 . 1 (2024) . |
| APA | Han, Pei-Rong , Ning, Wen , Huang, Xin-Jie , Zheng, Ri-Hua , Yang, Shou-Bang , Wu, Fan et al. Measuring topological invariants for higher-order exceptional points in quantum three-mode systems . | NATURE COMMUNICATIONS , 2024 , 15 (1) . |
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Parametrically driven nonlinear resonators represent a building block for realizing fault -tolerant quantum computation and are useful for critical quantum sensing. From a fundamental viewpoint, the most intriguing feature of such a system is perhaps the critical phenomena, which can occur without interaction with any other quantum system. The nonanalytic behaviors of its eigenspectrum have been substantially investigated, but those associated with the ground state wavefunction have largely remained unexplored. Using the quantum ground state geometric tensor as an indicator, we comprehensively establish a phase diagram involving the driving parameter epsilon and phase 0 . The results reveal that with the increase in epsilon , the system undergoes a quantum phase transition from the normal to the symmetry -breaking phase, with the critical point unaffected by 0 . Furthermore, the critical exponent and scaling dimension are obtained by an exact numerical method, which is consistent with previous works. Our numerical results show that the phase transition falls within the universality class of the quantum Rabi model. This work reveals that the quantum metric and Berry curvature display diverging behaviors across the quantum phase transition. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
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| GB/T 7714 | Zhang, Hao-long , Lu, Jia-hao , Chen, Ken et al. Critical quantum geometric tensors of parametrically-driven nonlinear resonators [J]. | OPTICS EXPRESS , 2024 , 32 (13) : 22566-22577 . |
| MLA | Zhang, Hao-long et al. "Critical quantum geometric tensors of parametrically-driven nonlinear resonators" . | OPTICS EXPRESS 32 . 13 (2024) : 22566-22577 . |
| APA | Zhang, Hao-long , Lu, Jia-hao , Chen, Ken , Yu, Xue-jia , Wu, Fan , Yang, Zhen-biao et al. Critical quantum geometric tensors of parametrically-driven nonlinear resonators . | OPTICS EXPRESS , 2024 , 32 (13) , 22566-22577 . |
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Understanding the dynamical behavior of a qubit in a reservoir is critical to applications in quantum technological protocols, ranging from quantum computation to quantum metrology. The effect of the reservoir depends on the reservoir's spectral structure as well as on the qubit-reservoir coupling strength. We here propose a measure for quantifying the non-Markovian effect of a reservoir with a Lorentzian spectrum, based on the maximum qubit-reservoir quantum entanglement that can be extracted. Numerical simulation shows that this entanglement exhibits a monotonous behavior in response to the variation of the coupling strength. We confirm the validity of this measure with an experiment where a superconducting qubit is controllably coupled to a lossy resonator, which acts as a reservoir for the qubit. The experimental results illustrate that the maximal extractable entanglement is progressively increased with the strengthening of non-Markovianity.
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| GB/T 7714 | Han, Pei-Rong , Wu, Fan , Huang, Xin-Jie et al. Characterization of non-Markovianity with maximal extractable qubit-reservoir entanglement [J]. | APPLIED PHYSICS LETTERS , 2024 , 125 (12) . |
| MLA | Han, Pei-Rong et al. "Characterization of non-Markovianity with maximal extractable qubit-reservoir entanglement" . | APPLIED PHYSICS LETTERS 125 . 12 (2024) . |
| APA | Han, Pei-Rong , Wu, Fan , Huang, Xin-Jie , Wu, Huai-Zhi , Yi, Wei , Wen, Jianming et al. Characterization of non-Markovianity with maximal extractable qubit-reservoir entanglement . | APPLIED PHYSICS LETTERS , 2024 , 125 (12) . |
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We investigate the quantum phase transition in the anisotropic Dicke model through an examination of the quantum geometric tensor of the ground state. In this analysis, two distinct classical limits exhibit their unique anisotropic characteristics. The classical spin limit demonstrates a preference for the rotating-wave coupling, whereas the classical oscillator limit exhibits symmetry in the coupling strength of the bias. The anisotropic features of the classical spin limit persist at finite scales. Furthermore, we observe that the interplay among the anisotropic ratio, spin length, and frequency ratio can collectively enhance the critical behaviors. This critical enhancement without a trade-off between these factors provides a flexible method for quantum precision measurement.
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| GB/T 7714 | Zhu, Xin , Lu, Jia-Hao , Ning, Wen et al. Quantum geometric tensor and critical metrology in the anisotropic Dicke model [J]. | PHYSICAL REVIEW A , 2024 , 109 (5) . |
| MLA | Zhu, Xin et al. "Quantum geometric tensor and critical metrology in the anisotropic Dicke model" . | PHYSICAL REVIEW A 109 . 5 (2024) . |
| APA | Zhu, Xin , Lu, Jia-Hao , Ning, Wen , Shen, Li-Tuo , Wu, Fan , Yang, Zhen-Biao . Quantum geometric tensor and critical metrology in the anisotropic Dicke model . | PHYSICAL REVIEW A , 2024 , 109 (5) . |
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Spontaneous symmetry breaking (SSB) plays a central role in understanding a large variety of phenomena associated with phase transitions, such as superfluid and superconductivity. So far, the transition from a symmetric vacuum to a macroscopically ordered phase has been substantially explored. The process bridging these two distinct phases is critical to understanding how a classical world emerges from a quantum phase transition, but so far remains unexplored in experiment. We here report an experimental demonstration of such a process with a quantum Rabi model engineered with a superconducting circuit. We move the system from the normal phase to the superradiant phase featuring two symmetry-breaking field components, one of which is observed to emerge as the classical reality. The results demonstrate that the environment-induced decoherence plays a critical role in the SSB.
Keyword ：
quantum phase transition quantum phase transition Rabi model Rabi model Schrodinger cat states Schrodinger cat states spontaneous symmetry breaking spontaneous symmetry breaking superconducting circuit superconducting circuit
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| GB/T 7714 | Ning, Wen , Zheng, Ri-Hua , Lue, Jia-Hao et al. Experimental observation of spontaneous symmetry breaking in a quantum phase transition [J]. | SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY , 2024 , 67 (2) . |
| MLA | Ning, Wen et al. "Experimental observation of spontaneous symmetry breaking in a quantum phase transition" . | SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY 67 . 2 (2024) . |
| APA | Ning, Wen , Zheng, Ri-Hua , Lue, Jia-Hao , Wu, Fan , Yang, Zhen-Biao , Zheng, Shi-Biao . Experimental observation of spontaneous symmetry breaking in a quantum phase transition . | SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY , 2024 , 67 (2) . |
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Quantum operations by utilizing the underlying geometric phases produced in physical systems are favoured due to their potential robustness. When a system in a non-degenerate eigenstate undergoes an adiabatically cyclic evolution dominated by its Hamiltonian, it will get a geometric phase, referred to as the Berry Phase. While a non-adiabatically cyclic evolution produces an Aharonov-Anandan geometric phase. The two types of Abelian geometric phases are extended to the non-Abelian cases, where the phase factors become matrix-valued and the transformations associated with different loops are non-commutable. Abelian and non-Abelian (holonomic) operations are prevalent in discrete variable systems, whose limited (say, two) energy levels, form the qubit. While their developments in continuous systems have also been investigated, mainly due to that, bosonic modes (in, such as, cat states) with large Hilbert spaces, provide potential advantages in fault-tolerant quantum computation. Here we propose a feasible scheme to realize non-adiabatic holonomic quantum logic operations in continuous variable systems with cat codes. We construct arbitrary single-qubit (two-qubit) gates with the combination of single- and two-photon drivings applied to a Kerr Parametric Oscillator (KPO) (the coupled KPOs). Our scheme relaxes the requirements of the previously proposed quantum geometric operation strategies in continuous variable systems, providing an effective way for quantum control.
Keyword ：
cat qubit cat qubit continuous variable systems continuous variable systems non-Abelian non-Abelian
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| GB/T 7714 | Zhang, Hao-Long , Kang, Yi-Hao , Wu, Fan et al. Non-adiabatic holonomic quantum operations in continuous variable systems [J]. | SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY , 2024 , 67 (6) . |
| MLA | Zhang, Hao-Long et al. "Non-adiabatic holonomic quantum operations in continuous variable systems" . | SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY 67 . 6 (2024) . |
| APA | Zhang, Hao-Long , Kang, Yi-Hao , Wu, Fan , Yang, Zhen-Biao , Zheng, Shi-Biao . Non-adiabatic holonomic quantum operations in continuous variable systems . | SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY , 2024 , 67 (6) . |
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We systematically characterize the dynamical evolution of time-parity (PT)-symmetric two-level systems with spin-dependent dissipations. If the control parameters of the gap are linearly tuned with time, the dynamical evolution can be characterized with parabolic cylinder equations which can be analytically solved. We find that the asymptotic behaviors of particle probability on the two levels show initial-state-independent redistribution in the slow-tuning-speed limit as long as the system is nonadiabatically driven across exceptional points. Equal distributions appear when the nondissipative Hamiltonian shows gap closing. As long as the nondissipative Hamiltonian displays level anticrossing, the final distribution becomes unbalanced. The ratios between the occupation probabilities are given analytically. These results are confirmed with numerical simulations. The predicted equal-distribution phenomenon may be used to identify the closing of the energy gap from anticrossing between two energy bands.
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| GB/T 7714 | Pan, Jian-Song , Wu, Fan . Nonadiabatic transitions in non-Hermitian PT-symmetric two-level systems [J]. | PHYSICAL REVIEW A , 2024 , 109 (2) . |
| MLA | Pan, Jian-Song et al. "Nonadiabatic transitions in non-Hermitian PT-symmetric two-level systems" . | PHYSICAL REVIEW A 109 . 2 (2024) . |
| APA | Pan, Jian-Song , Wu, Fan . Nonadiabatic transitions in non-Hermitian PT-symmetric two-level systems . | PHYSICAL REVIEW A , 2024 , 109 (2) . |
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