Precise control of spin-orbit coupling in a textured liquid crystal microcavity

Abstract

Controlling both orbital momentum and spin simultaneously in physics can enable various important applications and phenomena in condensed matter physics, quantum simulators and quantum information processing. One of the interesting examples in recent years is liquid crystal cavities, allowing precise tuning of cavity mode dispersion and in consequence realisation of photonic spin-orbit coupling (SOC) Hamiltonians by applying an external voltage. In particular, it is possible to observe the optical equivalent of the Rashba-Dresselhaus effect known from solid-state physics. In this work, we demonstrate a precise control of spin in localized optical cavity modes due to emerging photonic Rashba-Dresselhaus SOC. For this purpose we developed an electrically tunable optical cavity filled with birefringent liquid crystal (LC) and FIB-etched Gaussian-shaped defects on the dielectric mirrors. The Rashba-Dresselhaus regime has been observed in zero dimensional states of single Gaussian defects at room temperature. Localized states with well-defined orbital momentum acquired considerably high spin polarization emitting elliptically polarized light with sigma+ and sigma- components in opposite directions. Our work is a first step into textured liquid crystal cavities where interactions between spin and orbital degrees of freedom in synthetic quantum Hamiltonians with arbitrary potential landscapes can be investigated.