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Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)

Entangled Bright States of Light via with Matter-Light-Correlations in Harmonic Generation

Ihar Babushkin, Sili Yi, Olga V. Smirnova, Misha Ivanov

Published Jun 23, 2025• 0 citations
Publisher

Abstract

Attosecond science operates with strong optical fields, with a lot of photons generated in harmonics; because of this, attosecond light pulses are often believed classical (coherent) states. Even if recent experiments shattered this view [1], [2], it is unclear yet, what resources can be used to make such states quantum.
DOI
10.1109/cleo/europe-eqec65582.2025.11111222

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Non-classical and entangled light states are of fundamental interest in quantum mechanics and they are a powerful tool for the emergence of new quantum technologies. The development of methods that can lead to the generation of such light states is therefore of high importance. Recently, it has been demonstrated that intense laser-matter interactions can serve towards this direction. Specifically, it has been shown how the use of fully quantized approaches in intense laser-matter interactions and the process of high harmonic generation, can lead to the generation of high photon-number non-classical and entangled states from the far-infrared (IR) to the extreme-ultraviolet (XUV). Here, after a brief introduction on the fundamentals, we summarize the operation principles of these approaches and discuss the recent developments and future directions of non-classical light engineering using strong light fields with the potential application in ultrafast and quantum information science. These findings represent an important step in the development of novel quantum nonlinear spectroscopy methods, based on the interplay between the quantum properties of light and those of quantum matter.
At the fundamental level, full description of light-matter interaction requires quantum treatment of both matter and light. However, for standard light sources generating intense laser pulses carrying quadrillions of photons in a coherent state, the classical description of light during intense laser-matter interaction has been expected to be adequate. Here, we show how nonlinear optical response of matter can be controlled to generate dramatic deviations from this standard picture, including generation of several squeezed and entangled harmonics of the incident laser light. In particular, such nontrivial quantum states of harmonics are generated as soon as one of the harmonics induces a transition between different laser-dressed states of the material system. Such transitions generate an entangled light-matter wave function, which can generate quantum states of harmonics even in the absence of a quantum driving field or material correlations. In turn, entanglement of the material system with a single harmonic generates and controls entanglement between different harmonics. Hence, nonlinear media that are near resonant with at least one of the harmonics appear to be quite attractive for controlled generation of massively entangled quantum states of light. Our analysis opens remarkable opportunities at the interface of attosecond physics and quantum optics, with implications for quantum information science.