Towards quantum magnetomechanics – chip-based magnetic levitation of a superconducting microsphere

Magnetically-levitated superconducting microparticles make a promising system for probing quantum physics in unexplored high-mass regimes of ~1μg~10¹⁸amu [1]. We show initial steps in this direction. We trap a superconducting microparticle and aim to prepare its COM motion in quantum states. Our particle acts as an ideal diamagnet and is confined in a passive magnetic trap formed by superconducting currents. We use all-magnetic trapping, detection and feedback to avoid several limitations of optical levitation. Our system [2,3] is well isolated from the surroundings, in a dilution refrigerator at temperatures <100mK. Our magnetic trap’s and detection coils are microfabricated on a chip, which enables flexible control of the trapping potential, high and stable detection efficiencies and the potential to scale-up our system to an array of magnetically-levitated inertial sensors.



Our immediate goal is to cool a magnetically-levitated particle to the ground state, and from there to study quantum states of motion. To this end, we also aim to couple the particle's motion to a flux-tunable superconducting microwave resonator - which offers a higher read-out sensitivity – and facilitates access to the rich toolbox of optomechanical control protocols.