Phase coherence and fragmentation in weakly interacting bosonic gases

TL;DR

This paper develops a theoretical framework for understanding measurement-induced interference in weakly interacting Bose-Einstein condensates, showing how measurements break phase symmetry and produce observable interference patterns.

Contribution

It introduces a model approximating the many-body state as a superposition of GP states and analyzes measurement effects on phase symmetry in BECs.

Findings

Measurement breaks initial phase symmetry in BECs

Superposition of GP states describes many-body evolution

Analytical solutions for specific models like soliton generation

Abstract

We present a theory of measurement-induced interference for weakly interacting Bose-Einstein condensed (BEC) gases. The many-body state resulting from the evolution of an initial fragmented (Fock) state can be approximated as a continuous superposition of Gross-Pitaevskii (GP) states; the measurement breaks the initial phase symmetry, producing a distribution pattern corresponding to only one of the GP solutions. We discuss also analytically solvable models, such as two-mode on-chip adiabatic recombination and soliton generation in quasi one-dimensional condensates.