Entanglement and thermalization in the extended Bose–Hubbard model after a quantum quench: A correlation analysis

Exploring the role of entanglement in quantum nonequilibrium dynamics is important to understand the mechanism of thermalization in an isolated system. We study the relaxation dynamics in a one-dimensional extended Bose–Hubbard model after a global interaction quench by considering several observables: the local Boson numbers, the nonlocal entanglement entropy, and the momentum distribution functions. We calculate the thermalization fidelity for different quench parameters and different sizes of subsystems, and the results show that the degree of thermalization is affected by the distance from the integrable point and the size of the subsystem. We employ the Pearson coefficient as the measurement of the correlation between the entanglement entropy and thermalization fidelity, and a strong correlation is demonstrated for the quenched system.

Terahertz spectroscopy and lattice vibrational analysis of pararealgar and orpiment

Terahertz time-domain spectroscopy(THz-TDS)is an effective nondestructive and noninvasive tool for investigating sulfur-containing pigments.Combined with Raman spectroscopy and vibrational mode analysis,it is significant for artifact identification and conservation.In this work,the terahertz absorption spectra of pararealgar(As_(4)S_(4))and orpiment(As_(2)S_(3))samples mixed with polytetrafluoroethylene(PTFE)are characterized in a range from 0.2 THz to 2.2 THz,and their distinctive peaks are observed,respectively.Meanwhile,qualitative analysis is also implemented by using Raman spectroscopy as a complementary technique.The lattice vibrations are simulated by using solid-state density functional theory(ss-DFT),illustrating different characteristic absorption peaks for specific crystalline structures and dynamic properties.This work provides a reliable database of sulfur-containing pigments for using the THz technology to actually analyze and diagnose cultural relics.

Quantum quenches in the Dicke model:Thermalization and failure of the generalized Gibbs ensemble

Quantum quenches in the Dicke model were studied both in the thermodynamic limit and the finite systems.For the integrable situation in the thermodynamic limit,the generalized Gibbs ensemble can effectively describe the energylevel occupations for the quench within the normal phase,but it fails for the quench to the superradiant phase.For the finite systems which are considered non-integrable,the post quench systems were studied by comparing with the thermal ensembles.The canonical ensembles are directly available for the quench within the normal phase.With the increasing of the target coupling strength over the equilibrium phase transition critical point,sudden changes take place for the effective temperature and the distance to the thermal ensembles.The thermalization was also studied by comparing with the results of the microcanonical ensembles.