26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Symmetry broken optical resonators as sources of probabilistic bits

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral ANZOS | Photonics and Optics (ANZCOP)

Speaker

Stephane Coen (Department of Physics, University of Auckland)

Description

Conventional computing architectures rely on deterministic bits, ensuring consistent and repeatable operations. This paradigm can however be inefficient when modelling systems in which randomness plays a fundamental role. In contrast, probabilistic bits (P-bits), which fluctuate between binary states according to a controllable probability distribution, provide an attractive alternative for probabilistic computing and stochastic algorithms.

Here, we experimentally demonstrate a novel platform for all-optical P-bit generation based on polarization symmetry breaking in an externally driven passive Kerr resonator. Information is encoded in the polarization state of ultrashort pulses circulating in an optical fibre ring. The resonator is operated in a symmetry-protected regime where a roundtrip-to-roundtrip polarization flip cancels system asymmetries, producing a natively unbiased probability distribution. This distribution can then be very finely and reproducibly biased by injecting a weak phase-modulated optical field that is orthogonally polarized to the driving.

In our experiments, the resonator simultaneously holds 124 optical pulses, each representing an independent P-bit. Once the bias is established, the ensemble is sampled from a binomial distribution with a desired success likelihood every time the driving laser frequency is swept across resonance, enabling the generation of arbitrarily long P-bit sequences. Measurements show that the probability of obtaining a binary value of 1 follows an ideal sigmoidal dependence on the applied phase modulation amplitude, demonstrating that the circulating optical pulses can function as all-optical stochastic binary neurons. We further demonstrate experimental control over the sigmoid response through the bias optical power, down to fewer than three photons per bias pulse. This sensitivity, enabled by the symmetry protection, provides precise tuning of the generated P-bit distribution.
These experimental results establish a scalable photonic probabilistic computing platform based entirely on standard telecommunications components, offering compatibility with existing optical technologies while enabling straightforward scaling through higher repetition rates or longer resonators.