Light-matter interaction in optomechanical systems is the foundation for ultra-sensitive detection schemes measuring displacements, accelerations, and forces. In addition, this interaction enables the generation of phononic and photonic quantum states as well as entangled states of photons and phonons. Electromechanical systems implement optomechanics using microwave circuits. They have demonstrated ground state cooling, electromechanically induced transparency, and squeezing. However, most electromechanical devices realize the coupling in form of a mechanically compliant capacitance resulting in interaction rates of up to 280 Hz. This is far below the so-called vacuum strong-coupling regime that would unleash the full potential of the intrinsically nonlinear electromechanical interaction. However, early proposals and experiments suggest that inductive coupling schemes have the potential to reach the vacuum strong-coupling regime. In my talk I demonstrate an electromechanical coupling based on a partly suspended SQUID and observe a maximum coupling rate of 1.62 kHz. This allows for sub-aN/√Hz force-sensitivity using a single-photon ultra-low-power readout.
Host: M. Aspelmeyer