Nonclassical cutoff fluctuations in squeezed-light-driven high-harmonic generation
Year: 2026
Type: article
Abstract: In the conventional description of strong-field high-harmonic generation (HHG), the atom is treated quantum mechanically while the driving laser is represented by a classical field. Quantum fluctuations of the driver can become relevant in nanoscale interaction geometries, where tight spatial confinement can raise the vacuum-field amplitude to ∼ 10 − 2 of the mean driving-field amplitude. In this regime, fluctuations of a squeezed driver can imprint its quadrature statistics on HHG observables. To model this interaction, we sample the positive Wigner function of the driving field and solve the time-dependent Schrödinger equation for each sampled field realization. Within a single-mode Gaussian framework, we show that amplitude squeezing suppresses the shot-to-shot variance of the HHG cutoff below the coherent-state standard quantum limit (SQL) at the same mean field. To leading order in the vacuum-to-driver field ratio, the normalized variance follows e − 2 r , where r is the squeezing parameter, independently of the absolute vacuum-field amplitude. At stronger squeezing, quadratic coupling of the antisqueezed quadrature to the field modulus competes with this suppression, yielding a variance minimum near r opt ≈ 1.55 for the parameters studied. A sub-SQL cutoff variance thus indicates subvacuum noise in the quadrature probed by the cutoff, suggesting that shot-resolved HHG cutoff measurements could witness driving-field nonclassicality.
Source: Physical Review Research
DOI: 10.1103/ffdj-mz2y
Institutions: Griffith University, University of Southern Queensland
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,625
Funder: Australian Research Council
OpenAlex ID: W7162098800