Invited talk at KACST
I was invited by Prof. Mohammed Al-Amri to give a seminar at KACST on some of my recent work on photon correlations and their use in metrology, quantum communication, and authentication.
The talk was also an opportunity to present several results obtained within the ARTEMIS project and to discuss how information contained in photon statistics can be used beyond conventional intensity measurements.
Abstract
Photon correlations preserve information about light sources and propagation channels that disappears when a detection record is reduced to an average intensity. I will present several results obtained within ARTEMIS, an EIC Pathfinder project on integrated quantum light sources, and examine how this hidden structure can be used for metrology, quantum communication, and authentication.
For pulsed single-photon emitters diffusing through an observation volume, fluctuations in the emitter number can conceal antibunching and bring the measured second-order correlation close to the Poissonian value. Combining Hanbury Brown–Twiss measurements with fluorescence correlation spectroscopy separates these effects. It allows the emitter population, effective detection efficiencies, and diffusion dynamics to be inferred from the same time-tagged record.
Beyond revealing source dynamics, the electromagnetic environment can shape correlations between emitters. Geometry-controlled environmental memory can return coherence and revive Bell nonlocality.
When correlated photon pairs are distributed to separate detectors, coincidence-time postselection isolates jointly generated photons from accidental detections and background noise, supporting quantum key distribution over noisy links.
Within ARTEMIS, the same use of joint statistics is being explored for optical authentication, using molecular emitters and nanostructured environments to produce fingerprints that extend beyond brightness, spectrum, and lifetime.