Nb SQUIDs for the detection of the motion of macroscopic mechanical oscillators

Macroscopic mechanical oscillators can be used to investigate fundamental questions in macroscopic quantum physics and for quantum sensing applications. Such systems, however, suffer from decoherence effects, e.g. due to parasitic coupling to the environment or light absorption. Levitating solid-state objects, like a superconducting particle in a magnetic trap or a cantilever with a superconducting strip, offer a unique approach to the realization of nano- or even micro-sized quantum systems with potentially minimal decoherence. In combination with cryogenic temperatures, the coherence times in the quantum mechanical ground state can be increased significantly. To gain information on position and oscillatory behavior, a dc SQUID is employed. The results of numerical simulations and experimentally determined SQUID design performance will be presented. To optimize magnetic coupling between oscillator and SQUID, we performed numerical simulations based on London equations and evaluated various SQUID designs in order to optimize the expected magnetic flux signal originating from the mechanical oscillators. The results of the numerical simulations and experimentally determined SQUID performance will be presented.