High-fidelity optical readout of a superconducting qubit using a scalable piezo-optomechanical transducer (Part 2)*

Superconducting qubits have great potential as a scalable platform for quantum computing, but a number of challenges still remain. One challenge is the large volume and thermal loading of microwave cabling passing into and out of dilution refrigerators and the heat dissipation of microwave amplifiers. An alternative approach involves converting the weak microwave readout signal recovered from the qubit into an optical signal.[1] We present here high power, demolition readout of a superconducting transmon qubit with microwave and optical approaches.[2] We show that we can determine the state of the qubit with high fidelity, with less than 200 averages, without a quantum limited amplifier and with minimal optically induced adverse effects on the qubit. Replacement of heat dissipating microwave amplification with optical readout techniques should be possible with minor transducer improvements which will allow for thousands of channels in parallel in contemporary dilution refrigerators.

1. R. Delaney et al. Superconducting-qubit readout via low-backaction electro-optic transduction Nature 606, 489 (2022)

2. T.C. van Thiel et al. High-fidelity optical readout of a superconducting qubit using a scalable piezo-optomechanical transducer https://arxiv.org/abs/2310.06026 (2023)