Single photon detector measurement of a membrane transducer in a dilution refrigerator

Bidirectional microwave-to-optical frequency transducers will allow superconducting qubit nodes to be connected via networks of fiber optic cables. Transducers based on MHz-frequency Si3N4 membranes are promising platforms for this operation, and have demonstrated field-high bidirectional throughputs with close to single photon added noise [1]. However, for either heralded transduction or optical non-Gaussian mechanical state preparation, these membranes must be connected to an optical nonlinear resource like a single photon detector. I will present on technical improvements to measure a 5 MHz mechanical resonator in a dilution refrigerator while filtering the signal for single photon detention. Additionally, I will show noise thermometry of that device using the single photon detectors. 

[1] M. D. Urmey, S. Dickson, K. Adachi, S. Mittal, L. G. Talamo, A. Kyle, N. E. Frattini, S.-X. Lin, K. W. Lehnert, C. A. Regal, High-throughput electro-optic upconversion and downconversion with few-photon added noise, arXiv preprint arXiv:2507.09873 (2025).