Bogoliubov depletion of the fragmented condensate in the bosonic flux ladder

TL;DR

This paper theoretically investigates the ground state of weakly interacting bosons in a flux ladder, revealing a fragmented condensate in the vortex phase and analyzing its depletion via Bogoliubov theory, considering boundary effects.

Contribution

It introduces a theoretical analysis of the fragmented condensate in flux ladders, highlighting the role of boundary conditions and Bogoliubov depletion.

Findings

Ground state is a fragmented condensate in the vortex phase

Bogoliubov depletion affects the condensate stability

Boundary conditions influence the condensate properties

Abstract

We theoretically analyze the ground state of weakly interacting bosons in the flux ladder -- the system that has been recently realized by means of ultacold atoms in the specially designed optical lattice [M. Atala, et al., Nat. Phys. 10, 588 (2014)]. It is argued that, for the system parameters corresponding to the so-called `vortex phase', the ground state is a fragmented condensate. We study the Bogoliubov depletion of this condensate and discuss the role of boundary conditions.