Quantum computing promises a radically new way to solve classically intractable problems, with superconducting quantum processors as one of the leading platform. However, the required millikelvin temperatures and the finite cooling capacity of individual dilution refrigerator limit the number of qubits that can be hosted in a single system. Consequently, future large-scale quantum computers are expected to consist of multiple cryogenic modules, each containing one or more quantum processors, interconnected through quantum links.
We realize a modular cryogenic microwave link spanning distances of up to 30 meters that connects, through a quantum communication channel, two quantum processors housed in separate dilution refrigerators. We developed the cryogenic architecture through thermal modelling and iterative prototype development, resulting in optimized material selection, radiation shielding, heat transport, and compensation of thermal expansion. The assembled system reaches operating temperatures below 50 millikelvin along the entire link and supports continuous operation for about six months.
Utilizing this cryogenic link, we successfully generated remote entanglement and conducted non-local quantum experiments across the two quantum processors. These results prove the viability of meter-scale cryogenic microwave networks for distributed, large scale quantum computing.
 

Keywords
Cryogenic engineering|Quantum communication|Modular architecture|Dilution refrigerators|Superconducting circuits