Non-equilibrium dynamics of bosonic atoms in optical lattices: Decoherence of many-body states due to spontaneous emission

TL;DR

This paper investigates how incoherent light scattering causes heating and decoherence in many-body bosonic states in optical lattices, revealing the interplay between atomic physics and many-body dynamics, with results differing across interaction regimes.

Contribution

It provides a detailed analysis of heating effects due to spontaneous emission in many-body bosonic systems, combining perturbation theory and advanced numerical methods for 1D systems.

Findings

Heating rates vary with interaction strength and laser detuning.

Significant differences in decoherence between strongly and weakly interacting regimes.

Time-dependent DMRG with quantum trajectories effectively models dissipative dynamics.

Abstract

We analyze in detail the heating of bosonic atoms in an optical lattice due to incoherent scattering of light from the lasers forming the lattice. Because atoms scattered into higher bands do not thermalize on the timescale of typical experiments, this process cannot be described by the total energy increase in the system alone (which is determined by single-particle effects). The heating instead involves an important interplay between the atomic physics of the heating process and the many-body physics of the state. We characterize the effects on many-body states for various system parameters, where we observe important differences in the heating for strongly and weakly interacting regimes, as well as a strong dependence on the sign of the laser detuning from the excited atomic state. We compute heating rates and changes to characteristic correlation functions based both on perturbation theory calculations, and a time-dependent calculation of the dissipative many-body dynamics. The latter is made possible for 1D systems by combining time-dependent density matrix renormalization group (t-DMRG) methods with quantum trajectory techniques.