Observation of Thermalization and Information Scrambling in a Superconducting Quantum Processor

Zhu, Qing–Ling; Sun, Zheng‐Hang; Gong, Ming; Chen, Fusheng; Zhang, Yu-Ran; Wu, Yulin; Ye, Yangsen; Zha, Chen; Li, Shaowei; Guo, Shaojun; Qian, Haoran; Huang, He-Liang; Yu, Jiabing; Deng, Hui; Rong, Hao; Lin, Jin; Xu, Yu; Sun, Lihua; Guo, Cheng; Li, Na; Liang, Futian; Peng, Cheng-Zhi; Fan, Heng; Zhu, Xiaobo; Pan, Jian-Wei

doi:10.1103/physrevlett.128.160502

Cited by 36 publications

(21 citation statements)

References 56 publications

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“…In the NISQ era, quantum computers are not perfectly translation-invariant, due to their OBC [18,[41][42][43][44][45][46][47][66][67][68][69], and randomness induced by experimental imperfections. At the same time, for lack of efficient error correction technique for NISQ computers, the affordable circuit depth is also limited.…”

Section: Discussionmentioning

confidence: 99%

Improving the performance of quantum approximate optimization for preparing non-trivial quantum states without translational symmetry

Sun¹,

Wang²,

Cui³

et al. 2022

Preprint

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The variational preparation of complex quantum states using the quantum approximate optimization algorithm (QAOA) is of fundamental interest, and becomes a promising application of quantum computers. Here, we systematically study the performance of QAOA for preparing ground states of target Hamiltonians near the critical points of their quantum phase transitions, and generating Greenberger-Horne-Zeilinger (GHZ) states. We reveal that the performance of QAOA is related to the translational invariance of the target Hamiltonian: Without the translational symmetry, for instance due to the open boundary condition (OBC) or randomness in the system, the QAOA becomes less efficient. We then propose a generalized QAOA assisted by the parameterized resource Hamiltonian (PRH-QAOA), to achieve a better performance. In addition, based on the PRH-QAOA, we design a low-depth quantum circuit beyond one-dimensional geometry, to generate GHZ states with perfect fidelity. The experimental realization of the proposed scheme for generating GHZ states on Rydberg-dressing atoms is discussed. Our work paves the way for performing QAOA on programmable quantum processors without translational symmetry, especially for recently developed two-dimensional quantum processors with OBC.

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Section: Discussionmentioning

confidence: 99%

Improving the performance of quantum approximate optimization for preparing non-trivial quantum states without translational symmetry

Sun¹,

Wang²,

Cui³

et al. 2022

Preprint

Self Cite

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“…The bosonic excitations described by the model are microwave photons but we use the term 'boson' for generality in this article. In modern arrays of transmons [15,24,26], we have ω /2π ∼ 5 GHz for the on-site energies, J /2π ∼ 10 − 30 MHz for the hopping frequencies, and U /2π ∼ 200 − 250 MHz for the on-site interactions.Due to the inevitable small differences in manufactured devices, the parameters of any two transmons are usually not equal. However, for the sake of simplicity, we will assume in most parts of this work that there is no disorder in the parameters of the Hamiltonian, i.e., ω = ω, J = J, and U = U .…”

Section: Open Many-body Dynamics In a Transmon Arraymentioning

confidence: 99%

“…Transmon arrays have recently taken substantial advances in size, coherence, and controllability, opening doors for exciting demonstrations of quantum information protocols [1][2][3][4][5][6][7][8][9][10][11][12][13] and many-body simulations [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Transmons are typically operated as quantum two-level systems, qubits, despite their inherent nature as anharmonic oscillators with approximately d ∼ 5 − 10 welldefined quantum states [28].…”

Section: Introductionmentioning

confidence: 99%

Dissipation and Dephasing of Interacting Photons in Transmon Arrays

Busel¹,

Laine²,

Mansikkamäki³

et al. 2023

Preprint

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Transmon arrays are one of the most promising platforms for quantum information science. Despite being often considered simply as qubits, transmons are inherently quantum mechanical multilevel systems. Being experimentally controllable with high fidelity, the higher excited states beyond the qubit subspace provide an important resource for hardware-efficient many-body quantum simulations, quantum error correction, and quantum information protocols. Alas, dissipation and dephasing phenomena generated by couplings to various uncontrollable environments yield a practical limiting factor to their utilization. To quantify this in detail, we present here the primary consequences of single-transmon dissipation and dephasing to the many-body dynamics of transmon arrays. We use analytical methods from perturbation theory and quantum trajectory approach together with numerical simulations, and deliberately consider the full Hilbert space including the higher excited states. The three main non-unitary processes are many-body decoherence, many-body dissipation, and heating/cooling transitions between different anharmonicity manifolds. Of these, the many-body decoherence -being proportional to the squared distance between the many-body Fock states -gives the strictest limit for observing effective unitary dynamics. Considering experimentally relevant parameters, including also the inevitable site-to-site disorder, our results show that the state-of-theart transmon arrays should be ready for the task of demonstrating coherent many-body dynamics using the higher excited states. However, the wider utilization of transmons for ternary-and-beyond quantum computing calls for improving their coherence properties.

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“…Other systems used to measure OTOCs are superconducting qubits. Quantum thermalization and information scrambling were studied in the XX-ladder model and the one-dimensional XX model measuring OTOCs in a ladder-type superconducting quantum processor [162]. In Ref.…”

Section: Otoc and Experimentsmentioning

confidence: 99%

Out-of-time-order correlators and quantum chaos

García-Mata¹,

Jalabert²,

Wisniacki³

2022

Preprint

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Quantum Chaos has originally emerged as the field which studies how the properties of classical chaotic systems arise in their quantum counterparts. The growing interest in quantum many-body systems, with no obvious classical meaning has led to consider time-dependent quantities that can help to characterize and redefine Quantum Chaos. This article reviews the prominent role that the out of time ordered correlator (OTOC) plays to achieve such goal.

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Observation of Thermalization and Information Scrambling in a Superconducting Quantum Processor

Cited by 36 publications

References 56 publications

Improving the performance of quantum approximate optimization for preparing non-trivial quantum states without translational symmetry

Improving the performance of quantum approximate optimization for preparing non-trivial quantum states without translational symmetry

Dissipation and Dephasing of Interacting Photons in Transmon Arrays

Out-of-time-order correlators and quantum chaos

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