Coherent manipulation of spin wave vector for polarization of photons in an atomic ensemble

TL;DR

This paper demonstrates precise control of spin wave components in an atomic ensemble, enabling polarization manipulation of emitted photons for quantum information processing.

Contribution

It introduces a method for coherent rotation of spin wave components using Raman transitions and magnetic pulses, advancing quantum control techniques in atomic ensembles.

Findings

Achieved ~96% fidelity in Ramsey fringe measurements.

Demonstrated controllable coherent rotations of spin waves.

Mapped spin wave manipulations into orthogonal photon polarizations.

Abstract

We experimentally demonstrate the manipulation of two-orthogonal components of a spin wave in an atomic ensemble. Based on Raman two-photon transition and Larmor spin precession induced by magnetic field pulses, the coherent rotations between the two components of the spin wave is controllably achieved. Successively, the two manipulated spin-wave components are mapped into two orthogonal polarized optical emissions, respectively. By measuring Ramsey fringes of the retrieved optical signals, the \pi/2-pulse fidelity of ~96% is obtained. The presented manipulation scheme can be used to build an arbitrary rotation for qubit operations in quantum information processing based on atomic ensembles.