Local versus global equilibration near the bosonic Mott-superfluid transition

TL;DR

This study investigates how trapped two-dimensional cold bosons respond to time-dependent lattice ramps near the Mott-superfluid transition, revealing a separation of local and global equilibration timescales with implications for experiments.

Contribution

It demonstrates the different timescales of local versus global equilibration in cold bosonic systems near the Mott transition.

Findings

Local number fluctuations equilibrate within 3 ms during lattice ramps.

Global transport processes are significantly slower, taking around 1 second.

Separation of timescales affects experimental protocols and cooling strategies.

Abstract

We study the response of trapped two dimensional cold bosons to time dependent lattices. We find that in lattice ramps from 11 (superfluid, $\hbar/U_{\text{i}} = 3$ms, $\hbar/J_{\text{i}} = 45$ms) to 16 recoils (Mott, $\hbar/U_{\text{f}} = 2$ms, $\hbar/J_{\text{f}} = 130$ms) the local number fluctuations remains at their equilibrium values if ramps are slower than 3 ms. Global transport, however, is much slower (1s), especially in the presence of Mott shells. This separation of timescales has practical implications for cold atom experiments and cooling protocols.