Pranshu Dave | Searcharxiv

arXiv2026

Optical design for implementing non-collinear circularly polarized high harmonic generation in an enhancement cavity

We introduce an original optical cavity design intended to efficiently output-couple extreme ultraviolet (XUV) light produced via cavity-enhanced high harmonic generation (CE-HHG). It supports the amplification of oppositely circularly polarized modes, crossing with a small angle in the high finesse cavity, where circularly polarized HHG scheme (NCP-HHG) will be implemented. We present an analytical model, numerical simulations, and experimental results obtained with a low-power continuous (CW) laser, demonstrating the strong potential of the cavity as an efficient XUV output coupling method. In particular, it is well suited for producing the 7th harmonic (H7) from an Ytterbium frequency comb at 8.4 eV, which is of particular interest for precision nuclear spectroscopy of Thorium.

physics.optics↗

arXiv2026

Quantum optical photoelectron interferometry

We present a general theoretical framework for multiphoton processes driven by quantum light fields, establishing a direct link between photon statistics and photoelectron observables. Our results show that the autocorrelation and cross-correlation functions, which quantify the underlying photon statistics, are directly mapped onto the resulting photoelectron spectra. Although our framework is broadly applicable, we demonstrate specifically in the example of reconstruction of attosecond beating by interference of two-photon transitions (RABBIT) the influence of the light statistical properties. In this approach, the amplitude, contrast and phase of the oscillations of the sideband signal as a function of pump-probe delay reveal the quantum nature of light. We analyze these observables across several quantum configurations, including correlated infrared and harmonic modes, as well as the uncorrelated case with non-classical harmonic statistics, thereby establishing a general framework for quantum-light RABBIT spectroscopy. We compare the analytical theory with numerical simulations for the case of classical harmonics and an infrared field in a squeezed coherent state, obtaining excellent agreement. Our results reveal how the interplay between classical and quantum correlations dictates the coherence of the photoemission process, providing a new window into the quantum-optical foundations of attosecond science.

quant-ph↗