A nanomechanical-circuit QED analogue of the Unruh effect*

In the Unruh Effect (UE), a uniformly accelerating detector is predicted to `see' thermal photons in the vacuum. A longstanding challenge is to demonstrate the UE in tabletop experiments. However, impracticably high accelerations are required in order to produce a measurable thermal photon signal. An alternative approach is to consider condensed matter analogues, where the governing quantum dynamics closely maps onto that of the genuine UE, but which are more easily realised in experiment. We consider a feasible UE analogue involving two coupled superconducting circuit microwave resonators, one playing the role of the photon detector, the other the vacuum cavity. The coupling is via a GHz mechanically oscillating film bulk acoustic resonator, with its fundamental dilatational frequency matching the microwave resonators' fundamental frequencies, functioning effectively as a non-degenerate parametric amplifier with mechanical pump. We show how the resulting photon pair production from vacuum can be verified through available quantum limited linear detection techniques.