title: Melting of discrete vortices via quantum fluctuations.
abstract: We consider nonlinear boson states with a nontrivial phase structure in the three-site Bose-Hubbard ring, quantum discrete vortices (or 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.
authors.affiliation: Nonlinear Physics Centre and ARC Centre of Excellence for Quantum-Atom Optics, Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 0200, Australia.
authors.forename: Chaohong
authors.initials: C
authors.lastname: Lee
authors.forename: Tristram J
authors.initials: TJ
authors.lastname: Alexander
authors.forename: Yuri S
authors.initials: YS
authors.lastname: Kivshar