Polarisation rotation of slow light with orbital angular momentum in ultracold atomic gases

Abstract

We consider the propagation of slow light with an orbital angular momentum (OAM) in a moving atomic medium. We have derived a general equation of motion and applied it in analysing propagation of slow light with an OAM in a rotating medium, such as a vortex lattice. We have shown that the OAM of slow light manifests itself in a rotation of the polarisation plane of linearly polarised light. To extract a pure rotational phase shift, we suggest to measure a difference in the angle of the polarisation plane rotation by two consecutive light beams with opposite OAM. The differential angle $\Delta {\alpha }_{\ell }$ is proportional to the rotation frequency of the medium ${\omega }_{\mathrm{rot}}$ and the winding number $\ell$ of light, and is inversely proportional to the group velocity of light. For slow light the angle $\Delta {\alpha }_{\ell }$ should be large enough to be detectable. The effect can be used as a tool for measuring the rotation frequency ${\omega }_{\mathrm{rot}}$ of the medium.

5 pages, 1 figure

References in corpus (1)

• Pump-probe measurement of atomic parity violation in caesium with a precision of 2.6%

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