RT Journal Article SR Electronic T1 Probing dynamical phase transitions with a superconducting quantum simulator JF Science Advances JO Sci Adv FD American Association for the Advancement of Science SP eaba4935 DO 10.1126/sciadv.aba4935 VO 6 IS 25 A1 Xu, Kai A1 Sun, Zheng-Hang A1 Liu, Wuxin A1 Zhang, Yu-Ran A1 Li, Hekang A1 Dong, Hang A1 Ren, Wenhui A1 Zhang, Pengfei A1 Nori, Franco A1 Zheng, Dongning A1 Fan, Heng A1 Wang, H. YR 2020 UL http://advances.sciencemag.org/content/6/25/eaba4935.abstract AB Nonequilibrium quantum many-body systems, which are difficult to study via classical computation, have attracted wide interest. Quantum simulation can provide insights into these problems. Here, using a programmable quantum simulator with 16 all-to-all connected superconducting qubits, we investigate the dynamical phase transition in the Lipkin-Meshkov-Glick model with a quenched transverse field. Clear signatures of dynamical phase transitions, merging different concepts of dynamical criticality, are observed by measuring the nonequilibrium order parameter, nonlocal correlations, and the Loschmidt echo. Moreover, near the dynamical critical point, we obtain a spin squeezing of −7.0 ± 0.8 dB, showing multipartite entanglement, useful for measurements with precision fivefold beyond the standard quantum limit. On the basis of the capability of entangling qubits simultaneously and the accurate single-shot readout of multiqubit states, this superconducting quantum simulator can be used to study other problems in nonequilibrium quantum many-body systems, such as thermalization, many-body localization, and emergent phenomena in periodically driven systems.