Co-qlink: 56Gbps Cryogenic Optical Link Achieves 1.6pJ/b Data Transmission for Scalable Quantum Computing Systems

The increasing complexity of quantum and cryogenic computing demands efficient data transfer between extremely cold operating environments and room-temperature control systems, a challenge that traditional wired connections struggle to meet. Zheng Chang, Siqi Zhang, Wenqiang Huang, et al. address this critical need with a novel optical communication link, dubbed CO-QLink, which achieves a data rate of 56 gigabits per second while consuming minimal power. This breakthrough transceiver establishes a complete connection between 4 Kelvin cryogenic systems and standard room-temperature equipment, overcoming limitations of existing technologies through the use of innovative signal processing and a compact design. By eliminating thermal conduction and offering superior scalability, CO-QLink paves the way for larger, more powerful quantum computers and advanced cryogenic systems, and has already been successfully demonstrated in the control and readout of a complete superconducting quantum system.

Cryogenic systems require extensive data transmission both between room-temperature and cryogenic environments, and within the cryogenic temperature domain itself. High-speed, low-power data transmission is pivotal to enabling the deployment of larger-scale cryogenic systems, including scalable quantum computing systems and high-performance cryogenic computing systems fully immersed in liquid nitrogen. Optical communication links are emerging as a solution, offering high data rates, high energy efficiency, low signal attenuation, absence of thermal conduction, and superior scalability. This work presents a 4K heat-insulated high-speed optical link designed for cryogenic environments, demonstrating a viable pathway towards overcoming the data transmission bottlenecks currently limiting the performance of advanced cryogenic systems.

Cryogenic to Room-Temperature Optical Communication Link

This research details the development of an optical link designed to address the growing need for high-bandwidth, low-latency communication in quantum computing systems. As quantum computers scale up, efficiently transferring data out of the extremely cold (4K) environment to room-temperature control and processing systems becomes a significant bottleneck. The researchers have created an optical link that operates reliably between 4K and room temperature, enabling high-speed data transfer with improved efficiency and reach compared to existing solutions. This system functions reliably at 4 Kelvin, a crucial requirement for interfacing with superconducting qubits, and achieves high data rates, long communication distances, and low latency. This research represents a significant step towards building practical, scalable quantum computing systems. By solving the data egress problem, this optical link paves the way for larger quantum processors, seamless integration of quantum processors with classical computing resources, and potentially enables remote access and control of quantum computers.

Cryogenic Optical Link Achieves 56Gbps Data Transfer

Scientists have developed a groundbreaking cryogenic optical link, capable of high-speed, low-power data transmission between room-temperature and cryogenic environments, as well as within cryogenic systems. This achievement addresses a critical need for larger-scale cryogenic systems, including those used in advanced quantum computing and high-performance computing applications. The system delivers a data rate of up to 56Gbps while maintaining a remarkably low power consumption of 1. 6pJ/b, demonstrating significant improvements in energy efficiency for cryogenic data transfer. The core of this innovation lies in a fully integrated transceiver, incorporating both optical and electrical components operating at 4K, the extremely low temperature required for many quantum systems.

Experiments reveal that the system successfully establishes a complete data link between 4K cryogenic systems and room-temperature equipment, enabling bidirectional communication. The transmitter integrates a device to serialize data and modulate it onto a laser beam, while the receiver utilizes a specialized photodiode and a custom-designed receiver chip to accurately decode data. This innovative link has been successfully demonstrated in the control and readout of a complete superconducting quantum system, paving the way for scalable, high-performance quantum computing architectures.

Cryogenic Optical Link for Scalable Quantum Computing

This work demonstrates a 56 Gigabit-per-second optical transceiver capable of operating within and between cryogenic environments, specifically at 4 Kelvin. This achievement represents the first direct optical link for scalable quantum computing systems, enabling communication across multiple dilution refrigerators, and has been successfully integrated into a practical quantum computing system for control and readout. The transceiver achieves high data rates with energy efficiencies significantly outperforming existing wireline and microwave links. The developed system addresses a critical need for high-speed, low-power data transmission in increasingly complex cryogenic setups, essential for scaling quantum computing and high-performance cryogenic applications. While the system currently achieves a link reach exceeding 5 meters, future research directions include exploring further optimization of energy efficiency and investigating techniques to minimize heat dissipation, ultimately paving the way for even larger and more interconnected cryogenic systems.