Quantum Quench of an Atomic Mott Insulator

TL;DR

This paper investigates the dynamics of a quantum phase transition in ultra-cold atomic gases, revealing how excitation levels depend on quench rate and supporting a Kibble-Zurek mechanism analogy.

Contribution

It demonstrates the power-law relationship between excitations and quench rate during a quantum phase transition in a Bose-Hubbard system, linking to Kibble-Zurek physics.

Findings

Excitations proportional to atoms crossing the phase boundary

Power-law dependence of excitations on quench rate

Evidence supporting Kibble-Zurek mechanism in quantum phase transition

Abstract

We study quenches across the Bose-Hubbard Mott-insulator-to-superfluid quantum phase transition using an ultra-cold atomic gas trapped in an optical lattice. Quenching from the Mott insulator to superfluid phase is accomplished by continuously tuning the ratio of Hubbard tunneling to interaction energy. Excitations of the condensate formed after the quench are measured using time-of-flight imaging. We observe that the degree of excitation is proportional to the fraction of atoms that cross the phase boundary, and that the quantity of excitations and energy produced during the quench have a power-law dependence on the quench rate. These phenomena suggest an excitation process analogous to the Kibble-Zurek (KZ) mechanism for defect generation in non-equilibrium classical phase transitions.