Macroscopic Quantum Fluctuations in the Josephson Dynamics of Two Weakly Linked Bose-Einstein Condensates

TL;DR

This paper investigates quantum corrections to Josephson dynamics in two weakly linked Bose-Einstein condensates, revealing macroscopic quantum phenomena like collapses, revivals, and a new oscillation mode, bridging classical and quantum regimes.

Contribution

It introduces a detailed analysis of quantum fluctuations affecting Josephson oscillations and uncovers a novel inter-well oscillation mode with unique fluctuation properties.

Findings

Quantum fluctuations renormalize Josephson frequencies.

Large amplitude oscillations show collapses and revivals.

A new oscillation mode with oscillating fluctuations is described.

Abstract

We study the quantum corrections to the Gross-Pitaevskii equation for two weakly linked Bose-Einstein condensates. The goals are: 1) to investigate dynamical regimes at the borderline between the classical and quantum behaviour of the bosonic field; 2) to search for new macroscopic quantum coherence phenomena not observable with other superfluid/superconducting systems. Quantum fluctuations renormalize the classical Josephson oscillation frequencies. Large amplitude phase oscillations are modulated, exhibiting collapses and revivals. We describe a new inter-well oscillation mode, with a vanishing (ensemble averaged) mean value of the observables, but with oscillating mean square fluctuations. Increasing the number of condensate atoms, we recover the classical Gross-Pitaevskii (Josephson) dynamics, without invoking the symmetry-breaking of the Gauge invariance.