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arXiv · 2608.20119

Geometric Control of Cat States in High Harmonic Generation

Arti Gaharwar·Rocío Borrego-Varillas·Marcelo F. Ciappina·Anna G. Ciriolo·Javier Rivera-Dean·Philipp Stammer·Paraskevas Tzallas·Emilio Pisanty·Maciej Lewenstein
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Abstract

High-harmonic generation (HHG) provides a powerful platform for exploring the interaction between intense laser fields and matter on ultrafast timescales. Beyond its conventional description in terms of emitted radiation and electron dynamics, a fully quantum treatment of HHG reveals that the nonlinear light-matter interaction can modify the quantum state of the driving field itself, establishing correlations between the fundamental and harmonic modes. This perspective opens new possibilities for using HHG as a tool to engineer and control nonclassical states of light. In this work, we investigate the geometric properties of optical Schroedinger cat states generated in HHG via conditioning and post-selection. By analyzing the coherent-state displacements induced by different structured driving fields, we characterize the resulting phase-space evolution and the associated geometric phases of the generated quantum states. Particular emphasis is placed on how the polarization and spatial-mode structure of the driving light influence the geometry and evolution of displaced coherent states. Our results demonstrate that structured light offers a versatile means of controlling the geometric dynamics of HHG-generated cat states across the parameter space. Furthermore, we discuss the prospects for realizing genuinely topological optical cat states by exploiting more complex structured light configurations.

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Arti Gaharwar, Rocío Borrego-Varillas, Marcelo F. Ciappina, Anna G. Ciriolo, Javier Rivera-Dean, Philipp Stammer, Paraskevas Tzallas, Emilio Pisanty, Maciej Lewenstein. 2026-08-20. Geometric Control of Cat States in High Harmonic Generation. https://arxiv.org/abs/2608.20119

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