Noise in Bose Josephson junctions: Decoherence and phase relaxation

TL;DR

This paper provides an exact quantum dynamical analysis of Bose Josephson junctions under phase noise, revealing how classical noise affects decoherence, phase relaxation, and the stability of macroscopic superpositions, with implications for quantum interferometry.

Contribution

It offers an exact solution for the quantum dynamics of noisy Bose Josephson junctions, highlighting noise-induced decoherence effects independent of atom number.

Findings

Noise causes non-Markovian decay of visibility.

Decoherence rate among superposition components is atom-number independent.

Predicted anomalous decoherence has potential interferometric applications.

Abstract

Squeezed states and macroscopic superpositions of coherent states have been predicted to be generated dynamically in Bose Josephson junctions. We solve exactly the quantum dynamics of such a junction in the presence of a classical noise coupled to the population-imbalance number operator (phase noise), accounting for, for example, the experimentally relevant fluctuations of the magnetic field. We calculate the correction to the decay of the visibility induced by the noise in the non-Markovian regime. Furthermore, we predict that such a noise induces an anomalous rate of decoherence among the components of the macroscopic superpositions, which is independent of the total number of atoms, leading to potential interferometric applications.