Dispersive measurement of spin shot noise in a Bose--Einstein condensate

TL;DR

This paper demonstrates precise dispersive measurement of spin shot noise in a Bose--Einstein condensate using polarization rotation, enabling better understanding of quantum spin fluctuations and improving measurement precision for atomic sensors.

Contribution

It provides the first confirmative measurement of spin shot noise in a BEC using dispersive probing with polarization rotation at optimal detunings.

Findings

Achieved spin shot noise level measurement in a BEC of rubidium atoms.

Used two-color probe with power stabilization to suppress excess noise.

Opened new avenues for studying quantum spin fluctuations in spinor BECs.

Abstract

We report dispersive spin shot noise measurement of a Bose--Einstein condensate (BEC). While dispersive probing has been used for quantum spin noise measurement of thermal and cold gases for decades, confirmative measurement of spin shot noise, i.e.,\ the linear dependence of the spin variance on the number of atoms in a BEC has been lacking. Here, we demonstrate precise spin noise measurement of a BEC of rubidium atoms at the spin shot noise level by polarization rotation using a two-color probe at optimal detunings, with power balance stabilization to suppress probe-induced excess spin noise. This work opens the possibility for the unexplored study of quantum spin fluctuations in multi-component or spinor BECs and offers an approach to improve spin measurement precision, which is relevant to atomic spin-based sensors.