Quantum computers are theoretically capable of running calculations exponentially faster than classical computers, and can be made by exploiting atoms, superconductors, diamond crystals and more.
Once linked, these systems would talk to each other by sending and receiving photons.
The photons would encode quantum states but, unlike the voltages and currents interpreted by a classical computer chip, they cannot be transmitted via copper wires.
What’s more, quantum rules require that a single photon must essentially carry a spread of frequencies, rather than a single frequency.
For different components to talk to each other using photons, the spread of the sender’s photons must therefore be converted to the spread that the receiver can handle.
Finally, the photon is translated into another frequency that the receiving component can read. Only part of the system has been built so far: the researchers have managed to convert infrared photons to a visible wavelength – while leaving their quantum state intact – with a success rate of about 75 per cent.