Networks of coupled photon Bose-Einstein condensates: when condensation becomes a computation

Despite large advances in both algorithms and computer technology, even typical instances of computationally hard problems are too difficult to be solved on today’s computers.

Unconventional computational devices that break with the usual paradigms of digital electronic computers can help to overcome these limitations.

In this project, a network of coupled photon Bose-Einstein condensates will be developed and used as experimental platform to perform ultrafast simulations of classical spin systems. Specifically, the network will be capable of solving the ground-state problem in spin glasses (disordered magnets).

The latter constitutes a well-known combinatorial problem that can be mapped mathematically to many other computationally hard problems in machine learning, logistics, computer chip design and DNA sequencing.

In a proof-of-principle experiment, I aim to demonstrate that the proposed spin glass simulator performs this computationally hard optimisation problem significantly faster than any other computer today.

I have pioneered the Bose-Einstein condensation of photons in optical microcavities, which has enabled us to investigate this genuine quantum-mechanical effect with all-optical methods.

In a recent work of my group, we experimentally demonstrate controllable phase relations between photon Bose-Einstein condensates in an optical microcavity. The investigated device realises an optical analogue of a Josephson junction.

Similar to a transistor for electronics, a controllable photonic Josephson junction represents the key component for ultrafast optical spin glass simulation and, thus, is the crucial basis for the proposed project. The BEC-NETWORKS project will be the main research project of my research group at the University of Twente.