Rapid ground-state cooling of a solid-state nanoparticle assisted by a magnetic-field gradient

Abstract

Cooling a solid-state nanoparticle, as a significant prerequisite of the mesoscale quantum sensing, is experimentally challenging. Here we propose an efficient cooling scheme assisted by a strong magnetic-field gradient to cool a nanoparticle down to the ground state of the vibrational degrees of freedom. By combining the Zeeman effect with quantum interference effect, the scheme can accomplish the precooling of the nanoparticle from room temperature to the Doppler cooling limit in several seconds, and can then further cool the precooled nanoparticle to the vibrational ground state within milliseconds. We specify the scheme by exemplifying the nanocrystal of diamond nitrogen-vacancy center suspended in an electromagnetic potential, indicating that this cooling scheme can accomplish the ground-state cooling from room temperature within a few seconds under the condition of currently available techniques. Our work lays a foundation for further three-dimensional cooling of suspended nanoparticles and also for realizing quantum sensing using mesoscopic particles in the future.