N-conserving Bogoliubov vacuum of a two component Bose-Einstein condensate: Density fluctuations close to a phase separation condition

TL;DR

This paper develops a number-conserving Bogoliubov theory for two-component Bose-Einstein condensates, revealing significant density fluctuations near phase separation, applicable to both homogeneous and double-well systems.

Contribution

It introduces a simple particle representation of the Bogoliubov vacuum for two-component condensates and analyzes density fluctuations near phase separation.

Findings

Density fluctuations increase near phase separation.

The Bogoliubov vacuum state can be expressed simply in particle representation.

Results apply to both homogeneous and double-well condensates.

Abstract

Two-component Bose-Einstein condensates are considered within a number conserving version of the Bogoliubov theory. We show that the Bogoliubov vacuum state can be obtained in the particle representation in a simple form. We predict considerable density fluctuations in finite systems close to the phase-separation regime. We analyze homogeneous condensates and condensates in a double-well potential.