Nonlinear atomic tunnelling boosted by bright squeezed vacuum
Main Nonlinear light–matter interactions driven by multiple photons enable revolutionary abilities beyond perturbative optics, in contrast to the well-known single-photon process. At the heart of these laser-driven nonlinear processes lies tunnelling ionization 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , which forms the cornerstone of ultrafast science. It not only drives femtochemistry 13 , 14 , 15 , 16 but also serves as the vital first step in high-harmonic generation (HHG) 17 , 18 , 19 , 20 , 21 —the primary mechanism for producing attosecond pulses 22 , 23 , 24 —thereby enabling the direct exploration of electron dynamics on its natural time scale 25 , 26 , 27 , 28 , 29 , 30 , 31 . However, conventional approaches using coherent light enhance tunnelling ionization through brute-force intensity scaling face an inherent limitation: material damage threshold constrains maximum accessible intensity of the laser field. Quantum light, for example, bright squeezed light, breaks this pattern by leveraging intrinsic photon correlations and enhanced amplitude fluctuation 1 , 2 . These quantum properties enable a superior nonlinear boost at low excitation powers, accessing non-classical interaction regimes impossible with coherent light 32 , 33 , 34 .
Nonlinear atomic tunnelling boosted by bright squeezed vacuum. Main Nonlinear light–matter interactions driven by multiple photons enable revolutionary abilities beyond perturbative optics, in contrast to the well-known single-photon process. At the heart of these laser-driven nonlinear processes lies tunnelling ionization 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , which forms the cornerstone of ultrafast science. It not only drives femtochemistry 13 , 14 , 15 , 16 but also serves as the vital first step in high-harmonic generation (HHG) 17 , 18 , 19 , 20 , 21 —the primary mechanism for producing attosecond pulses 22 , 23 , 24 —thereby enabling the direct exploration of electron dynamics on its natural time scale 25 , 26 , 27 , 28 , 29 , 30 , 31 . However, conventional approaches using coherent light enhance tunnelling ionization through brute-fo...