Loschmidt amplitude spectrum in dynamical quantum phase transitions
- URL: http://arxiv.org/abs/2203.06991v1
- Date: Mon, 14 Mar 2022 10:54:31 GMT
- Title: Loschmidt amplitude spectrum in dynamical quantum phase transitions
- Authors: Cheuk Yiu Wong, Wing Chi Yu
- Abstract summary: We study how the system behaves in the vicinity of dynamical quantum phase transitions (DQPTs)
Our findings provide a better understanding of the characteristics of the out-of-equilibrium system around DQPT.
- Score: 0.0
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: Dynamical quantum phase transitions (DQPTs) are criticalities in the time
evolution of quantum systems and their existence has been theoretically
predicted and experimentally observed. However, how the system behaves in the
vicinity of DQPT and its connection to physical observables remains an open
question. In this work, we introduce the concept of the Loschmidt amplitude
spectrum (LAS), which extends the Loscmidt amplitude - the detector of the
transition - by considering the overlap of the initial state to all the
eigenstates of the prequench Hamiltonian. By analysing the LAS in the
integrable transverse-field Ising model, we find that the system undergoes a
population redistribution in the momentum space across DQPT. In the
quasiparticle picture, all the lower-half k modes are excited when the system
is at DQPT. The LAS is also applicable to study the dynamics of non-integrable
models where we have investigated the Ising model with next-nearest-neighbour
interactions as an example. The time evolution of the system's magnetization is
found to be connected to the products of the LAS and there exists a
simultaneous overlap of the time-evolved state to pairs of eigenstates of the
prequnech Hamiltonian that possess spin configurations of negative
magnetization. Our findings provide a better understanding of the
characteristics of the out-of-equilibrium system around DQPT.
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