Control and readout of a superconducting qubit using a photonic link

TL;DR

This paper introduces a photonic link using optical fiber for controlling and reading out superconducting qubits, aiming to scale quantum processors to millions of qubits by reducing complexity and heat load.

Contribution

It presents a novel optical fiber-based method for microwave signal delivery, enabling high-fidelity qubit control and readout at cryogenic temperatures, facilitating scalable quantum computing.

Findings

Successful demonstration of high-fidelity qubit control and readout

Photonic link reduces thermal load and complexity in quantum processors

Potential for massively multiplexed control of large qubit arrays

Abstract

Delivering on the revolutionary promise of a universal quantum computer will require processors with millions of quantum bits (qubits). In superconducting quantum processors, each qubit is individually addressed with microwave signal lines that connect room temperature electronics to the cryogenic environment of the quantum circuit. The complexity and heat load associated with the multiple coaxial lines per qubit limits the possible size of a processor to a few thousand qubits. Here we introduce a photonic link employing an optical fiber to guide modulated laser light from room temperature to a cryogenic photodetector, capable of delivering shot-noise limited microwave signals directly at millikelvin temperatures. By demonstrating high-fidelity control and readout of a superconducting qubit, we show that this photonic link can meet the stringent requirements of superconducting quantum information processing. Leveraging the low thermal conductivity and large intrinsic bandwidth of optical fiber enables efficient and massively multiplexed delivery of coherent microwave control pulses, providing a path towards a million-qubit universal quantum computer.