Quantum technology: Quantum computing goes virtual

A method for generating multimode entangled states of photons is shown in this week’s Nature Communications. The scheme relies on linear optics networks, allowing for versatility and rapid switching in real time, which could be exploited in quantum computing.

Quantum technologies rely on entanglement between particles in order to carry out functions. Larger quantum computers of quantum communications resources will require ever larger amounts of entangled particles. In most photon-based schemes, this requires multiple detectors and many optical components to create the entanglement between different sub-divided light beams. Seiji Armstrong and colleagues remove these complications by generating entanglement between different spatial regions of a single light beam. A pair of multi-pixel detectors is used to capture these different parts in one measurement, and a computer processes the information through programmed networks that emulate those for multiple beam setups. The authors demonstrate entanglement between up to eight modes of the beam and create cluster states for up to four modes.

The approach is scalable to large numbers of entangled modes and because the networks are virtual, they can be altered rapidly to optimise their output or switch their functionality.