A wireless terahertz cryogenic interconnect that minimizes heat-to-information transfer

Abstract

The development of practical quantum computers probably requires error-protected quantum processors with thousands of logical qubits. Reaching this scale potentially involves millions of physical qubits and scaled interconnects. The interconnects need to connect qubits operating at cryogenic temperature with a controller at a high-temperature stage. Conventional coaxial cables introduce conductive heat loads, and thus, optical interconnects using low-thermal-conductivity fibre links have been explored. However, each absorbed photon in the low-temperature stage involves considerable heating, as well as effects such as quasiparticle excitations. Here we report a wireless terahertz cryogenic interconnect that is based on complementary metal–oxide–semiconductor technology and minimizes the heat-to-information transfer ratio. Our architecture consists of integrated wideband transceivers operating at a carrier frequency of 260 GHz, a hot-to-cold ingress based on passive cold field-effect transistor terahertz detector and a cold-to-hot egress using ultralow-power backscatter modulation at the cold reservoir. Our terahertz quantum interconnect technology could potentially provide high-capacity reconfigurable multichannel cryo-interconnects that operate near the fundamental limits of information transfer.