Probing two-particle exchange processes in two-mode Bose-Einstein condensates

TL;DR

This paper investigates how two-particle exchange processes affect fidelity decay in two-mode Bose-Einstein condensates, revealing scaling properties and conditions for their detection, with implications for cold atom interferometry.

Contribution

It introduces a theoretical framework to identify two-particle mode-exchange in Bose-Einstein condensates via fidelity analysis and scaling laws.

Findings

Fidelity decay exhibits specific scaling with particle number.

Non-degeneracy condition reveals two-particle exchange effects.

Tuning energy difference uncovers singularities indicating exchange processes.

Abstract

We study the fidelity decay and its freeze for an initial coherent state of two-mode Bose-Einstein condensates in the Fock regime considering a Bose-Hubbard model that includes two-particle tunneling terms. By using linear-response theory we find scaling properties of the fidelity as a function of the particle number that prove the existence of two-particle mode-exchange when a non-degeneracy condition is fulfilled. Tuning the energy difference of the two modes serves to distinguish the presence of two-particle mode-exchange terms through the appearance of certain singularities. Numerical results confirm our findings. Experimental verification of our findings could improve cold atom interferometry.