Quantum Enhanced Probabilistic Computing in Symmetry-Broken Resonators

This study aims to build a versatile optical fibre system that will serve as a scalable and robust platform for a new analogue computing architecture. It will also provide insights into the quantum dynamics of nonlinear optical systems and the fundamental physics of spontaneous symmetry breaking. The project aims to harness the inherently unbiased nature of protected symmetry-breaking in an optical fibre-ring resonator to successfully realize three related applications:  quantum random number generation (QRNG), the creation of probabilistic bits (P-bits), and a novel photonic Ising machine (PIM).  

The project aims to both significantly increase the bit-generation speed of a previously constructed all-optical truly-random number generator (RNG) and rigorously prove that vacuum fluctuations underpin its randomness. This would deliver a commercially viable generator for advanced cryptographic and statistical applications. To address the need for tunable probability distributions, this team will inject calibrated bias fields into the resonator to generate probabilistic bits (P-bits) with arbitrary state-selection probabilities. It is expected that fields containing, on average, as few as a single photon per pulse may provide quantum-level control of the system’s multi-stability. The combination of intrinsic quantum randomness with programmable probabilistic hardware, opens a powerful route to other applications including quantum-enhanced sensing.

Finally, the study will use the resonator configuration as a photonic Ising machine (PIM). By coupling together many individual pulses through a measurement and feedback system, the team aims to emulate a network of bistable oscillators that collectively solve arbitrary Ising problems. The approach holds promise for tackling important combinatorial tasks exemplified by the travelling salesman problem for applications in logistics and manufacturing or new drug and material searches. In parallel to the ongoing system construction, the team will investigate whether quantum noise correlations below the bifurcation threshold can enable a quantum-parallel search across phase space, enhancing computational performance.

This project is led by Professor Stéphane Coen, together with Professor Miro Erkintalo, Associate Professor Stuart Murdoch and postdoctoral fellow Dr Liam Quinn. They will collaborate with internationally renowned researchers at the French National Research Agency (CNRS) and at the University of Strathclyde, United Kingdom.