Melting of Discrete Vortices via Quantum Fluctuations

TL;DR

This paper investigates how quantum fluctuations cause the melting of quantum discrete vortices in a three-site Bose-Hubbard ring, revealing their role in the superfluid-insulator transition.

Contribution

It introduces the concept of quantum discrete vortices and analyzes their stability and melting due to quantum fluctuations in a Bose-Hubbard model.

Findings

Quantum fluctuations lead to the breakdown of phase coherence in q-vortices.

The superfluid-insulator crossover is associated with the melting of quantum vortices.

Fidelity analysis confirms the classical analysis validity in certain regimes.

Abstract

We consider nonlinear boson states with a nontrivial phase structure in the three-site Bose-Hubbard ring, {\em quantum discrete vortices} (or {\em q-vortices}), and study their "melting" under the action of quantum fluctuations. We calculate the spatial correlations in the ground states to show the superfluid-insulator crossover and analyze the fidelity between the exact and variational ground states to explore the validity of the classical analysis. We examine the phase coherence and the effect of quantum fluctuations on q-vortices and reveal that the breakdown of these coherent structures through quantum fluctuations accompanies the superfluid-insulator crossover.