Splitting and merging an elongated Bose-Einstein condensate at finite temperature

TL;DR

This paper investigates how finite-temperature phase fluctuations affect the coherence during splitting and merging of elongated Bose-Einstein condensates, showing that adiabatic processes can produce a single condensate despite thermal effects.

Contribution

It provides a detailed analysis of finite-temperature effects on coherence during condensate splitting and merging, highlighting conditions for successful single condensate formation.

Findings

At zero temperature, condensates merge with negligible phase difference.

Finite temperature increases phase and density fluctuations during processes.

Adiabatic splitting and merging can produce a single condensate even at high temperatures.

Abstract

We analyze coherence effects during the splitting of a quasi one-dimensional condensate into two spatially separated ones and their subsequent merging into a single condensate. Our analysis takes into account finite-temperature effects, where phase fluctuations play an important role. We show that, at zero-temperature, the two split condensates can be merged into a single one with a negligible phase difference. By increasing temperature to a finite value below the critical point for condensation ($T_c$), i.e., $0 \le T/T_c < 1$, a considerable enhancement of phase and density fluctuations appears during the process of splitting and merging. Our results show that if the process of splitting and merging is sufficiently adiabatic, the whole process is quite insensitive to phase fluctuations and even at high temperatures, a single condensate can be produced.