Analog quantum simulation of high-harmonic generation in cavity QED

Abstract

High-harmonic generation (HHG) is the process where an intense laser field drives electron dynamics to emit high-frequency radiation and it stands as the cornerstone of attosecond science. However, because traditional HHG is driven by macroscopic, classical laser fields, exploring the underlying quantum properties of the emitted light—such as squeezing, entanglement, and non-classical photon statistics—remains a formidable experimental challenge. In this thesis, we propose an analog simulator for HHG in a cavity QED architecture, where an atom trapped in an optical tweezer directly mimics an electron bound to a nuclear potential. The driving electric field is simulated by the dispersive force of an optical cavity, which is proportional to the cavity’s oscillating photon number. We show analytically that by combining this optical force with a static bias, the strictly positive cavity photon number mimics the alternating, ultra-intense electric field characteristic of standard HHG. Crucially, the interaction force naturally inherits the quantum character of the cavity field and the external cavity drive, enabling the direct observation of quantum-optical HHG. We numerically verify the underlying classical-analog mapping by solving the Time-Dependent Schrödinger Equation (TDSE) for the atomic wavepacket, confirming that the dynamics exhibit the characteristic HHG emission spectrum. Finally, we detail the experimental feasibility of the platform using state-of-theart Rydberg systems. This work bridges the gap between strong-field physics and quantum optics, offering a fully controllable environment to explore the extreme non-linear dynamics of HHG in the quantum regime.