Bosonic quantum dynamics following a linear interaction quench in finite optical lattices of unit filling

TL;DR

This paper investigates the nonequilibrium dynamics of ultracold bosons in finite optical lattices following a linear interaction quench, revealing resonant responses, transport pathways, and effects of system size and lattice depth.

Contribution

It provides a detailed analysis of the dynamical response and higher-band excitations in finite optical lattices during interaction quenches, highlighting the role of quench rate, lattice depth, and system size.

Findings

Resonant dynamical response at moderate ramp times due to avoided crossings.

Higher-band excitation dynamics follow a two-scale exponential decay.

Increasing system size enhances excited to higher-band fraction.

Abstract

The nonequilibrium ultracold bosonic quantum dynamics in finite optical lattices of unit filling following a linear interaction quench from a superfluid to a Mott insulator state and vice versa is investigated. The resulting dynamical response consists of various inter and intraband tunneling modes. We find that the competition between the quench rate and the interparticle repulsion leads to a resonant dynamical response, at moderate ramp times, being related to avoided crossings in the many-body eigenspectrum with varying interaction strength. Crossing the regime of weak to strong interactions several transport pathways are excited. The higher-band excitation dynamics is shown to obey an exponential decay possessing two distinct time scales with varying ramp time. Studying the crossover from shallow to deep lattices we find that for a diabatic quench the excited band fraction decreases, while approaching the adiabatic limit it exhibits a non-linear behavior for increasing height of the potential barrier. The inverse ramping process from strong to weak interactions leads to a melting of the Mott insulator and possesses negligible higher-band excitations which follow an exponential decay for decreasing quench rate. Finally, independently of the direction that the phase boundary is crossed, we observe a significant enhancement of the excited to higher-band fraction for increasing system size.