High-fidelity optical readout of a superconducting qubit using a scalable piezo-optomechanical transducer (Part 1)*

Optimizing space in a cryostat is becoming more relevant with the increasing number of superconducting qubits in a system. Microwave-to-optics transduction would reduce the heatload and size of in-and output channels by substituting coaxial cables with multiplexed optical fibres. We demonstrate readout of superconducting qubits using a compact, fully integrated piezo-optomechanical transducer. The design couples a silicon photonic cavity to a piezoelectric lithium niobate block, which is subsequently coupled to a tunable superconducting resonator.[1] Microwave-to-optics conversion with efficiency up to 1.1% is achieved with 6 µW of optical power. With this device, a multishot readout fidelity of >99% is achieved with as few as 200 averages.[2] Our results show the potential to integrate thousands of optical readout devices into the dilution refrigerator. The transducer is highly scalable due to its footprint of less than 0.15 mm² and its modular connection to the qubit.

1. M.J. Weaver et al. An integrated microwave-to-optics interface for scalable quantum computing Nature Nanotechnology (2023)

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)