Incorporating single-photon counting with an efficient electro-optic transducer (parts II)

A sufficiently efficient and low-noise transducer linking microwave and optical frequencies would enable entanglement between superconducting quantum registers separated by long distances. In the presence of inevitable transmission losses, single-photon detection can be leveraged to trade success probability for improved fidelity of such entanglement. We present the experimental incorporation of optical photon counting with a high-efficiency transducer. This transducer links microwave and optical fields via simultaneous coupling to the same mechanical mode of a MHz-frequency silicon nitride membrane. We demonstrate the implementation of single-photon detection to characterize the transducer while operated with its mechanical mode close to the ground state. Part II of this presentation focuses on the addition of this capability with the electro-optic transducer.