Developments in magneto-mechanics using a cantilever coupled to a SQUID*

Tools provided by cavity optomechanics enable near quantum-limited motion control of macroscopic mechanical systems through interaction with light. Historically, in microwave optomechanics, the coupling between a microwave cavity and a mechanical resonator has been provided by a moving capacitance. However, this approach is ultimately limited by the capacitor gap, providing single-photon coupling of the order of g₀/2π ~ 300 Hz, often requiring a large intracavity photon number to enhance the total coupling rate (g = g₀√n). Further increasing this coupling would enable many applications such as the preparation of non-Gaussian mechanical states or more efficient quantum information processing.

In this talk, I will present the progress made at M1 Quantum Lab toward reaching single-photon strong coupling using magneto-mechanical devices based on inductive (i.e., flux-mediated) coupling. Using this approach, devices have demonstrated a single-photon coupling rate increase by more than an order of magnitude compared to the capacitive approach [1,4]. It can further be enhanced by increasing the non-linearity of the microwave cavity, by engineering the magnetic flux, or by changing the nature of the mechanics. The modular nature of our devices allows independent optimization of all three elements. Results related to the effects of each are presented.