CO-QLink: Cryogenic Optical Link for Scalable Quantum Computing Systems and High-Performance Cryogenic Computing Systems

TL;DR

This paper presents a cryogenic optical transceiver capable of high-speed, low-power data transmission between 4K cryogenic systems and room temperature, enabling scalable quantum computing and cryogenic computing systems.

Contribution

It introduces a novel 4K heat-insulated optical transceiver with 56Gbps speed and 1.6pJ/b energy efficiency, suitable for large-scale cryogenic applications.

Findings

Achieved 56Gbps data rate at 4K temperature.

Demonstrated successful control and readout of a superconducting quantum computer.

Low power consumption of 1.6pJ per bit.

Abstract

Cryogenic systems necessitate extensive data transmission between room-temperature and cryogenic environments, as well as within the cryogenic temperature domain. High-speed, low-power data transmission is pivotal to enabling the deployment of larger-scale cryogenic systems, including the scalable quantum computing systems and the high-performance cryogenic computing systems fully immersed in liquid nitrogen. In contrast to wireline and microwave links, optical communication links are emerging as a solution characterized by high data rates, high energy efficiency, low signal attenuation, absence of thermal conduction, and superior scalability. In this work, a 4K heat-insulated high-speed (56Gbps) low-power (1.6pJ/b) transceiver (TRX) that achieves a complete link between 4K systems and room temperature (RT) equipment is presented. Copackaged with a PIN photodiode (PD), the RX uses an inverter-based analog front-end and an analog half-rate clock data recovery loop. Connecting to a Mach-Zehnder modulator (MZM), the TX contains a voltage-mode driver with current-mode injection for low-power output-swing-boosting and 3-tap feed-forward equalization (FFE). This link has been demonstrated in the control and readout of a complete superconducting quantum computing system.