Conference Agenda

Optical microcavities have emerged as a powerful platform for investigating fundamental aspects of non-relativistic quantum mechanics, owing to recent advances in controlling the transverse state of light in these systems. We recently employed this platform to explore a long-standing question in quantum tunnelling. While quantum tunnelling has been studied since the early days of quantum mechanics, certain aspects—particularly the duration of tunnelling events—remain contentious.

In our experiment, we examine the motion of two-dimensional photons within a system of two coupled waveguide potentials, imprinted as a height profile on one of the cavity mirrors. In this system, the transfer of population between the waveguides serves as a clock, allowing us to measure particle speeds along the waveguide axis.

Applying this technique to exponentially decaying quantum states at a reflective potential step, we establish an energy-speed relationship for tunnelling particles. Our results reveal that lower-energy particles exhibit higher measured speeds within the potential step. These findings contribute to the discourse on tunnelling times and, independently, serve as a test of Bohmian trajectories in quantum mechanics. Regarding the latter, our observed energy-speed relationship is found to be inconsistent with the particle dynamics predicted by the guiding equation in Bohmian mechanics.

Second-order nonlinear optical materials with high refractive index and wide transparency range are of high demand for various photonic applications. Here, we present nanostructures fabricated in wafer-bonded crystalline aluminum indium phosphide (AlInP). The nanostructures exhibit strong enhancement of second-harmonic generation due to higher-order anapole excitations. Our results illustrate the potential of AlInP for nonlinear nanophotonics.

Terahertz technologies offer unique advantages for communication, sensing, and imaging, yet integrated platforms struggle to perform efficiently in this range. Thin-film lithium niobate, a nonlinear photonic platform, enables compact, broadband, and high-speed terahertz sources through efficient frequency conversion. In this talk, I present our progress on developing sub-terahertz continuous-wave sources on lithium niobate chips, aiming to bridge the gap between electronic and photonic systems for next-generation terahertz integration.

We have observed for the first time a parametric down conversion process within a solitonic waveguide. This feature ensures an optimal mode-overlapping between the interacting waves. Moreover, the excited photorefractive nonlinearity enables a phase-locking regime that allows the temporal overlapping of the interacting pulses too. A broadband PDC is then possible within a waveguide without special needs for phase-matching and temporal sinchronisation.

Traditionally, the resolution of optical microscopes is limited to about half the wavelength used. Single-Molecule Localization Microscopy (SMLM) achieves super-resolution by isolating blinking fluorophores across multiple acquisition frames, reaching resolutions down to single nanometers. However, high-density samples present challenges, as overlapping point spread functions (PSFs) limit accurate localization with conventional, e.g. sCMOS, detectors. Single-Photon Avalanche Diode (SPAD) arrays offer new quantum correlation-enhanced techniques to improve detection sensitivity and emitter density resolution in SMLM. Here, we demonstrate a photon-correlation-based approach for multi-emitter fitting and high-density SMLM in a scanning configuration.

A 23-pixel SPAD array with integrated time-correlated photon counting is used as the detector in a fluorescence confocal-scanning microscope. Crucially, fluorophores are single-photon emitters. The photon arrival times are used to compute the second-order quantum correlation of the signal, which is directly related to the number of emitters in the scanning location. This information makes it possible to locate fluorophores with overlapping point spread functions, consequently, SPAD arrays provide the ability to image in high emitter densities, which enables faster data acquisition and dynamic imaging.