ECAMP 15

Intense laser-matter interaction leads to high harmonic generation (HHG), where the low frequency photons of a driving laser field are converted into photons of higher frequencies. This process has enabled breakthroughs in AMO physics and attosecond science [1]. Until recently, it was described by classical or semi-classical approaches [2], ignoring the quantum nature of light.
Recent investigations conducted using fully quantized approaches have shown how the HHG process can be used for the generation of optical Schrödinger "cat" and entangled light states from the infrared to the extreme-ultraviolet spectral range [3-10].
Here, after a brief introduction, I will focus my talk on the most recent studies concerning the generation of optical "cat" states and their role in nonlinear optics [11]. I will also emphasize the potential of using fully quantum approaches in laser-driven semiconductor crystals to develop non-classical and entangled light states in the VUV spectral region with attosecond pulse duration [12]. Finally, I will briefly discuss some additional representative key approaches developed in the recent past by other groups in this research field [13-19].

References
[1] P. Agostini, F. Krausz and A. L’Huillier Nobel prize in physics 2023
[2] K. Amini, et al., Rep. Prog. Phys. 82, 116001 (2019) (and references herein).
[3] M. Lewenstein, et al., Nat. Phys. 17, 1104 (2021).
[4] J. Rivera-Dean, et al., Phys. Rev. A 105, 033714 (2022).
[5] P. Stammer, et al., PRL 128, 123603 (2022).
[6] J. Rivera-Dean arXiv:2409.02016
[7] P. Stammer arXiv:2410.15503
[8] P. Stammer, et al., PRX Quantum 4, 010201 (2023).
[9] U. Bhattacharya, et al., Rep. Prog. Phys. 86, 094401 (2023).
[10] J. Rivera-Dean et al., PRB 109, 035203 (2024).
[11] Th. Lamprou, et al., PRL 134, 013601 (2025).
[12] A. Nayak et al., Nat. Commun. 16,1428 (2025)
[13] M. E. Tzur, et al., Nat. Photon. 17, 501 (2023).
[14] A. Gorlach, et al., Nat. Phys. 19, 1689 (2023)
[15] J. Heimerl, et al., Nat. Phys. 20, 945 (2024).
[16] D. Theidel, et al., PRX Quantum 5, 040319 (2024).
[17] S. Lemieux, et al., arXiv:2404.05474 (2024).
[18] A. Rasputnyi, et al., Nat. Phys. 20, 1960 (2024).
[19] S. Yi, et al., Phys. Rev. X 15, 011023 (2025).