Dynamic freezing of strongly correlated ultracold bosons

TL;DR

This paper investigates the non-equilibrium dynamics of ultracold bosons in an optical lattice, revealing a phenomenon called dynamic freezing where the wavefunction remains nearly unchanged at specific driving frequencies.

Contribution

It introduces the concept of dynamic freezing in strongly correlated bosonic systems driven through a quantum critical point, supported by theoretical analysis and robustness checks.

Findings

Wavefunction overlap approaches unity at specific frequencies

Residual energy is minimized at freezing points

Superfluid order parameter remains stable during freezing

Abstract

We study the non-equilibrium dynamics of ultracold bosons in an optical lattice with a time dependent hopping amplitude J(t)=J_0 +\delta J \cos(\omega t) which takes the system from a superfluid phase near the Mott-superfluid transition (J= J_0+\delta J) to a Mott phase (J=J_0-\delta J) and back through a quantum critical point (J=J_c) and demonstrate dynamic freezing of the boson wavefunction at specific values of \omega. At these values, the wavefunction overlap F (defect density P=1-F) approaches unity (zero). We provide a qualitative explanation of the freezing phenomenon, show it's robustness against quantum fluctuations and the presence of a trap, compute residual energy and superfluid order parameter for such dynamics, and suggest experiments to test our theory.