Wang, QianPérez Bernal, Francisco2019-01-172019-01-172019Wang, Q., & Pérez-Bernal, F. (2019). Probing an excited-state quantum phase transition in a quantum many-body system via an out-of-time-order correlator. In Physical Review A (Vol. 100, Issue 6). American Physical Society (APS). https://doi.org/10.1103/physreva.100.0621132469-99262469-9934 (electrónico)http://hdl.handle.net/10272/15802Out-of-time-order correlators (OTOCs) play an increasingly important role in different fields of physics and in particular they provide a way of quantifying information scrambling in quantum many-body systems. We verify that an OTOC can be used to probe an excited-state quantum phase transition (ESQPT) in a quantum many-body system. We examine the dynamical properties of an OTOC in the Lipkin-Meshkov-Glick model, which undergoes an ESQPT, using the exact diagonalization method. We show that the long-time evolution of the proposed OTOC is remarkably different in the different phases of the ESQPT. In consequence, we put the long-time averaged value of the OTOC forward as a possible ESQPT order parameter. Our results highlight the connections between OTOCs and ESQPTs, opening the possibility of using OTOCs for accessing experimentally ESQPTs in quantum many-body systems.engAtribución-NoComercial-SinDerivadas 3.0 Españahttp://creativecommons.org/licenses/by-nc-nd/3.0/es/Quantum phase transitionsQuantum many body systemjournal article10.1103/PhysRevA.100.062113open access