Slow Mass Transport and Statistical Evolution of An Atomic Gas Across the Superfluid-Mott Insulator Transition

TL;DR

This study investigates the slow mass transport and evolution of an ultracold atomic gas across the superfluid-Mott insulator transition, revealing extremely slow equilibration times and changes in occupancy distribution.

Contribution

It provides the first detailed observation of global mass redistribution and slow dynamics during the superfluid-Mott insulator transition in a 2D atomic gas.

Findings

Mass transport slows dramatically in the Mott insulator regime

Global redistribution takes over 100 times longer than microscopic timescales

Occupancy distribution evolves slowly, indicating long-lived non-equilibrium states

Abstract

We study transport dynamics of ultracold cesium atoms in a two-dimensional optical lattice across the superfluid-Mott insulator transition based on in situ imaging. Inducing the phase transition with a lattice ramping routine expected to be locally adiabatic, we observe a global mass redistribution which requires a very long time to equilibrate, more than 100 times longer than the microscopic time scales for on-site interaction and tunneling. When the sample enters the Mott insulator regime, mass transport significantly slows down. By employing fast recombination pulses to analyze the occupancy distribution, we observe similarly slow-evolving dynamics, and a lower effective temperature at the center of the sample.