Experimental Observation of Equilibrium and Dynamical Quantum Phase Transitions via Out-of-Time-Ordered Correlators

Xinfang Nie, Bo-Bo Wei, Xi Chen, Ze Zhang, Xiuzhu Zhao, Chudan Qiu, Yu Tian, Yunlan Ji, Tao Xin, Dawei Lu, and Jun Li

Phys. Rev. Lett. 124, 250601 – Published 22 June 2020

Abstract

The out-of-time-ordered correlators (OTOC), a fundamental concept for quantifying quantum information scrambling, has recently been suggested to be an order parameter to dynamically detect both equilibrium quantum phase transitions (EQPTs) and dynamical quantum phase transitions (DQPTs). Here we report the first experimental observation of EQPTs and DQPTs in a quantum spin chain via quench dynamics of OTOC on a nuclear magnetic resonance quantum simulator. We observe that the quench dynamics of the OTOC can unambiguously detect the DQPTs and the equilibrium critical point, while conventional order parameters such as the longitudinal magnetization can not. Moreover, we investigate the two-body correlations throughout the quench dynamics, and find that OTOC can extract the equilibrium critical point with higher accuracy and is more robust to decoherence than that of two-body correlation. Our experiment paves a way for experimentally investigating DQPTs through OTOCs and for studying the EQPTs through the nonequilibrium quantum quench dynamics with quantum simulators.

Received 26 December 2019
Accepted 12 June 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.250601

Physics Subject Headings (PhySH)

Quantum phase transitions Quantum simulation

Quantum Information, Science & Technology

Authors & Affiliations

Xinfang Nie^1,2,3,*, Bo-Bo Wei^4,*, Xi Chen³, Ze Zhang¹, Xiuzhu Zhao¹, Chudan Qiu¹, Yu Tian¹, Yunlan Ji¹, Tao Xin^1,2,†, Dawei Lu ^1,2,‡, and Jun Li^1,2,§

¹Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
²Guangdong Provincial Key Laboratory of Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
³CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
⁴School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Shenzhen 518172, China

^*These authors contributed equally to this work.
^†xint@sustech.edu.cn
^‡ludw@sustech.edu.cn
^§lij3@sustech.edu.cn

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Vol. 124, Iss. 25 — 26 June 2020

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