Quantum back-action in spinor condensate magnetometry

TL;DR

This paper develops a theoretical framework for understanding how quantum measurement backaction affects spinor Bose-Einstein condensates during magnetometry, introducing a jump operator model and a stochastic master equation.

Contribution

It introduces a novel quantum jump operator description and a conditional stochastic master equation for modeling measurement backaction in spinor condensates.

Findings

Quantum jump operator model for single-photon detection effects.

Derivation of a stochastic master equation linking measurement record to condensate evolution.

Application potential in quantum metrology and many-body physics.

Abstract

We provide a theoretical treatment of the quantum backaction of Larmor frequency measurements on a spinor Bose-Einstein condensate by an off-resonant light field. Two main results are presented; the first is a "quantum jump" operator description that reflects the abrupt change in the spin state of the atoms when a single photon is counted at a photodiode. The second is the derivation of a conditional stochastic master equation relating the evolution of the condensate density matrix to the measurement record. We comment on applications of this formalism to metrology and many-body studies.