Quantum Optomechanics of a Bose-Einstein Antiferromagnet

We investigate the cavity optomechanical properties of an antiferromagnetic Bose-Einstein condensate, where the role of the mechanical element is played by spin-wave excitations. We show how this system can be described by a single rotor that can be prepared deep in the quantum regime under realizable experimental conditions. This system provides a bottom-up realization of dispersive rotational optomechanics, and opens the door to the direct observation of quantum spin fluctuations.

Figure 1

Average roton occupation number $\overline{n}$ as a function of scaled static detuning for $T=2\mu \mathrm{K}$ and 500 pK, $U_0=2\pi \times 100\mathrm{Hz}$, $\gamma =2\pi \times 50\mathrm{kHz}$, ${\kappa }_L=2\pi \times 3\mathrm{MHz}$.