Number squeezing, quantum fluctuations and oscillations in mesoscopic Bose Josephson junctions

TL;DR

This paper investigates the ground state, momentum distribution, and dynamics of a Bose Josephson junction using a two-mode Bose-Hubbard model, revealing regimes of suppressed fluctuations, interference effects, and Schrödinger cat states.

Contribution

It provides a detailed analysis of quantum fluctuations, number squeezing, and interference phenomena in mesoscopic Bose Josephson junctions, including the formation of Schrödinger cat states.

Findings

Identification of Mott-like regions with suppressed number fluctuations

Observation of reduced interference fringes in momentum distribution

Demonstration of destructive interference from Schrödinger cat states

Abstract

Starting from a quantum two-mode Bose-Hubbard Hamiltonian we determine the ground state properties, momentum distribution and dynamical evolution for a Bose Josephson junction realized by an ultracold Bose gas in a double-well trap. Varying the well asymmetry we identify Mott-like regions of parameters where number fluctuations are suppressed and the interference fringes in the momentum distribution are strongly reduced. We also show how Schroedinger cat states, realized from an initially phase coherent state by a sudden rise of the barrier among the two wells, will give rise to a destructive interference in the time-dependent momentum distribution.