Measurement schemes for the spin quadratures on an ensemble of atoms

TL;DR

This paper proposes a simplified multi-pass optical measurement scheme for homodyne tomography of collective atomic spin states, enhancing experimental efficiency in quantum interfaces.

Contribution

It introduces a two-pass light scheme for spin quadrature measurement, simplifying the experimental setup for atomic ensemble quantum state tomography.

Findings

Two-pass scheme effectively measures spin quadratures.

Optical pulses used as phase-shifters to rotate spin quadratures.

Simplifies experimental geometry for quantum measurements.

Abstract

We consider how to measure collective spin states of an atomic ensemble based on the recent multi-pass approaches for quantum interface between light and atoms. We find that a scheme with two passages of a light pulse through the atomic ensemble is efficient to implement the homodyne tomography of the spin state. Thereby, we propose to utilize optical pulses as a phase-shifter that rotates the quadrature of the spins. This method substantially simplifies the geometry of experimental schemes.