Cavity Cooling of an Ensemble Spin System

We describe how sideband cooling techniques may be applied to large spin ensembles in magnetic resonance. Using the Tavis-Cummings model in the presence of a Rabi drive, we solve a Markovian master equation describing the joint spin-cavity dynamics to derive cooling rates as a function of ensemble size. Our calculations indicate that the coupled angular momentum subspaces of a spin ensemble containing roughly $10^{11}$ electron spins may be polarized in a time many orders of magnitude shorter than the typical thermal relaxation time. The described techniques should permit efficient removal of entropy for spin-based quantum information processors and fast polarization of spin samples. The proposed application of a standard technique in quantum optics to magnetic resonance also serves to reinforce the connection between the two fields, which has recently begun to be explored in further detail due to the development of hybrid designs for manufacturing noise-resilient quantum devices.

Figure 1

Simulated evolution of the normalized expectation value of $-⟨J_x(t)⟩/J$ for the Dicke subspace of a cavity-cooled spin ensemble. The time axis is scaled by the effective dissipation rate, ${\mathrm{\Gamma }}_s$, for the spin-ensemble given in Eq. (16).