Quantum computers promise to solve computational problems that are intractable by even the most powerful supercomputers. Since quantum processors must typically operate at cryogenic temperatures, several research groups and companies from all over the world are currently developing cryogenic electronics to drive and read out the quantum devices. However, a large amount of data still must be transmitted from the room-temperature control electronics to the cryogenic system and viceversa.

Optical communication for quantum computing

High-speed data could be transmitted using a coaxial wire and a classical wireline transceiver. However, such a transceiver would dissipate significant power and the coaxial wire would conduct heat that could also leak into the refrigerator, thus possibly warming up the cryogenic refrigerator hosting the quantum processor and causing malfunctions. Furthermore, the high-frequency signal could generate electromagnetic interference that would disrupt the quantum operation. As an alternative, this project will explore high-speed data transfer through an optical fiber, which would offer very high speed with high power efficiency, low thermal leakage through the optical fiber, and no electromagnetic interference.

Challenges ahead

To realize the vision of a high-speed cryogenic optical link, several challenges must be overcome. For instance, the proper electro-optical transducers must be identified and their cryogenic behavior must be analyzed. An optimal communication scheme must be devised, eventually exploiting the asymmetry of the link with one node at room temperature, where virtually unlimited resources are available, and one cryogenic node constrained in terms of power dissipation and volume. Finally, cryogenic electronics with high power efficiency must be designed and experimentally demonstrated. Bringing all those elements together we will advance toward the development of a large-scale quantum computer capable of addressing real-life problems.