Creation, detection and decoherence of Schrodinger cat states in Bose-Einstein condensates

TL;DR

This paper explores creating and detecting Schrödinger cat states in Bose-Einstein condensates, analyzing decoherence mechanisms like photon scattering and atom collisions, and their impact on quantum superposition stability.

Contribution

It introduces a method to generate cat states via Feshbach resonance and investigates how environmental interactions cause decoherence and collapse.

Findings

Single photon scattering can collapse perfect cat states.

Less-than-perfect cat states can withstand multiple photon scatterings.

Atom-atom collisions induce dephasing of the superposition.

Abstract

We study the possibility to create many-particle Schr\"odinger cat-like states by using a Feshbach resonance to reverse the sign of the scattering length of a Bose-Einstein condensate trapped in a double-well potential. To address the issue of experimental verification of coherence in the cat-like state, we study the revival of the initial condensate state in the presence of environmentally-induced decoherence. As a source of decoherence, we consider the interaction between the atoms and the electromagnetic vacuum, due to the polarization induced by an incident laser field. We find that the resulting decoherence is directly related to the rate at which spontaneously scattered photons carry away sufficient information to distinguish between the two atom-distributions which make-up the cat state. We show that for a 'perfect' cat-state, a single scattered photon will bring about a collapse of the superposition, while a less-than-perfect cat-like state can survive multiple scatterings before collapse occurs. In addition, we study the dephasing effect of atom-atom collisions on the cat-like states.