Photonics circuit shown to handle quantum information

The team showed that a multimode interference device (MMI) — a basic photonic circuit frequently used in classical optics — can be adapted to handle quantum information.

‘We can ride on the back of the existing telecommunications industry through the fibres that are already in the ground. The photonic devices we are using are pretty well established. What we’re doing is reconfiguring them and making them work in a quantum regime,’ said Prof Jeremy O’Brien of Bristol University.

Quantum computing has been muted for some time now. It exploits the notion that a unit of information can represent both a one and a zero state simultaneously. The potential power of quantum computing comes from the possibility of performing a mathematical operation on both states simultaneously.

While O’Brien believes that a full-scale quantum computer is at least several decades away, the underlying technology has tangible applications in the medium term in things such as secure communications and metrology — the ability to model chemical and energy reactions with supreme precision.