Exotic signature of dynamical quantum phase transition in the time evolution of an engineered initial state
Abstract
Dynamical phase transition in quantum many body systems is usually studied by taking it in the ground state and then quenching a parameter to a new value. We investigate here the dynamics when one performs the time evolution of a generic state and observe that the rate function related to the Loschmidt echo shows nonanalytic behavior of two types, one related, and the other unrelated, to the appearance of a quantum phase transition. Specifically, we consider a quantum Ising chain in an initial configuration which is a generic superposition of the eigenstates, and follow its dynamics under the transverse Ising Hamiltonian with a constant field. Depending on the the configuration of the initial state, some singularities appear in the rate function which do not correspond to the equilibrium phase transition of the Hamiltonian. However another class of singularity is found having a connection with the quantum critical point. Some features of the singularities of the rate function have been derived analytically and it is observed that the occupancy of quasiparticle eigenstates plays the key role in triggering the nonanalyticities.
 Publication:

Journal of Physics A Mathematical General
 Pub Date:
 July 2020
 DOI:
 10.1088/17518121/ab8f3b
 arXiv:
 arXiv:1912.00207
 Bibcode:
 2020JPhA...53z5002B
 Keywords:

 Loschmidt echo;
 dynamical quantum phase transition;
 quantum phase transition;
 Fisher zero;
 Condensed Matter  Statistical Mechanics;
 Quantum Physics
 EPrint:
 7 pages, 3 figures