The single-atom box: bosonic staircase and effects of parity

TL;DR

This paper presents a theory of a Josephson junction with strongly interacting Bose-Einstein condensates, revealing a parity-sensitive single-atom staircase and its effects on interference visibility in lattice junctions.

Contribution

It introduces a comprehensive theory for bosonic Josephson junctions with strong interactions, highlighting the parity-dependent staircase structure for arbitrary atom numbers.

Findings

Discovery of a parity-sensitive single-atom staircase in the junction

Periodic modulation of interference visibility with bias energy

The staircase persists even for large atom numbers

Abstract

We have developed a theory of a Josephson junction formed by two tunnel-coupled Bose-Einstein condensates in a double-well potential in the regime of strong atom-atom interaction for an arbitrary total number $N$ of bosons in the condensates. The tunnel resonances in the junction are shown to be periodically spaced by the interaction energy, forming a single-atom staircase sensitive to the parity of $N$ even for large $N$. One of the manifestations of the staircase structure is the periodic modulation with the bias energy of the visibility of the interference pattern in lattices of junctions.