High-harmonic generation by a bright squeezed vacuum

• DOI: 10.1038/s41567-024-02659-x
• Publication Date: 2024-10-02T10:02:19Z
• Authors: Andrei Rasputnyi; Zhaopin Chen; Michael Birk; Oren Cohen; Ido Kaminer; Michael Krüger; Denis Seletskiy; Maria Chekhova; Francesco Tani

AbstractHigh-harmonic generation has been driving the development of attosecond science and sources. More recently, high-harmonic generation in solids has been adopted by other communities as a method to study material properties. However, so far high-harmonic generation has only been driven by classical light, despite theoretical proposals to do so with quantum states of light. Here we observe non-perturbative high-harmonic generation in solids driven by a macroscopic quantum state of light, a bright squeezed vacuum, which we generate in a single spatiotemporal mode. The process driven by a bright squeezed vacuum is considerably more efficient in the generation of high harmonics than classical light of the same mean intensity. Due to its broad photon-number distribution, covering states from 0 to 2 × 1013 photons per pulse, and strong subcycle electric field fluctuations, a bright squeezed vacuum gives access to free carrier dynamics within a much broader range of peak intensities than accessible with classical light.