Why is it difficult?

Creating a large-scale quantum computer relies on connecting millions of quantum units called qubits with each other and the processor. The quantum machine depends on the coupling of qubits to create a building block for quantum computing analogous to logic gates made of transistors in the classical domain. It is hard to connect these millions of qubits because laying millions of wires would increase the size and complexity of the computing machines while risking the cryogenic sub-10 milli-Kelvin temperatures required for these machines. Even the current wireless technology cannot be miniaturized to a small scale while posing an even higher risk of cross-talks. Photonics is also a potential candidate due to low loss connectivity, but no practical systems have been developed for small-scale photonics.

What is the impact?

The technological innovation that solves the wiring problem in a quantum machine would bring a tremendous improvement in quantum information processing. It will bring more flexibility in controlling a group of qubits and allow packing millions of qubits into a small form factor. Such improvements will reduce the size of a quantum computer and improve the portability of these devices similar to today’s general-purpose classical computers.