Background

Superconducting quantum computers rely on carefully shaped microwave pulses delivered to a cryogenic environment to control and readout the quantum state of each qubit. Presently, these pulses are generated at room temperature and then routed through heavily filtered and attenuated coaxial transmission lines to the qubits held at sub-100 mK temperatures. As these systems continue to scale, the heat load, cost, and complexity of a large number of coaxial microwave signal lines become significant limitations. Photonic links offer a potential scaling solution, due to their large intrinsic bandwidth, low noise, and the low thermal conductivity of optical fibers.

Leveraging the low thermal conductivity and large intrinsic bandwidth of optical fiber enables efficient and massively multiplexed delivery of coherent microwave control pulses at ultra-cryogenic temperature, providing a path towards a million-qubit universal quantum computer.

Technology Overview

Researchers at the University of Colorado - Boulder and the National Institute of Standards and Technology (NIST) have demonstrated the control and readout of a superconducting qubit using microwave signals transmitted over optical fiber and photodetected at 20 mK. This represents the first photonic link to a superconducting qubit and represents the first step in establishing cryogenic photonic links as a viable path towards large-scale quantum information systems with superconducting qubits. This technology is applicable to any system requiring the massive delivery of high-speed electrical signal to ultra-cryogenic temperatures ().

Further Details:

Control and readout of a superconducting qubit using a photonic link

Stage of Development

Technology Readiness Level (TRL): 3.

Benefits

Heat load of an optical fiber is up to 1000x less than the heat load of a coaxial cable with 100x the bandwidth
Allows for the ability to control 10x to 1000x more qubits
Decreased cost

Applications

Quantum computing
Cryogenic detectors (astronomy, imaging)
Classical computing

System for Microwave Signal Delivery to Superconducting Qubits via a Photonic Link