Space and cooling limitations restrict the number of usable qubits. However, researchers believe connecting two qubits in separate dilution refrigerators using an optical fiber is now possible.

“The infrastructure is available, and we can now build the first simple quantum computing networks,” says Arnold.

While the ISTA physicists have made significant progress in developing superconducting quantum hardware, more work is needed. Their prototype has limited performance, especially in terms of optical power. Nevertheless, it proves that a fully optical readout of superconducting qubits is possible, and further advancements will depend on the industry.