High-Fidelity, Scalable Quantum-Classical Control Interface using Photonics

Quantum computing (QC) has been hailed as the next big leap for the digital age; however, state-of-the-art QC devices have yet to surpass classical computers. One bottleneck is in the number of quantum operations that can be done within a qubit lifetime, also known as the "circuit depth". The circuit depth on current hardware is limited to 10-100 operations due to uncontrolled coupling to the classical environment, infidelities in the qubit operations and the gate operation time.
Effective control signal generation is essential to extending the circuit depth by improving classical control over the quantum system. To address this need, we propose an RF-photonic implementation of a QC control interface, via high-fidelity, scalable quantum drive signal generation and fiber optic transport of this signal to the qubit. By increasing the signal dynamic range and bandwidth, the time per quantum gate operation can be reduced, thus widening the circuit depth bottleneck. Additionally, replacing RF cabling with optical fiber reduces waste heat and thermalization issues, improving scalability to larger qubit systems. We show experimental results from a single-channel system and discuss its extension to a multi-channel system via simulations.