Probing an excited-state quantum phase transition in a quantum many-body system via an out-of-time-order correlator

Wang Q. Wang Q. Pérez-Bernal F.
Physical Review A
Doi 10.1103/PhysRevA.100.062113
Volumen 100
2019-12-10
Citas: 14
Abstract
© 2019 American Physical Society.Out-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.
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