From classical to quantum nature of high harmonic generation

Wednesday, January 17, 2024 - 3:00pm

SpeakerHamed Merdji, Ecole Polytechnique

Program Description:

I will review my recent progresses in high harmonic generation (HHG) in semiconductors, stepping from its classical nature to the recent evidence of its non-classical properties. First, I will first present classical high-harmonic generation in semiconductor and show how a strong laser polarization dependence can be used to gate isolated attosecond pulses. I will also present how semicondcutor nanostructuration can be use to taylor and boost the HHG process. In the last part of the seminar, I will show how high-harmonic generation can potentially generate non-classical states of light. Evidence of the quantum nature of HHG is demonstrated in several semiconductors (Si, ZnO GaAs) excited by a femtosecond mid-infrared fiber laser (Theidel et al, submitted to Nature, in review). By investigating single- and double beam intensity cross-correlation, we observe two-mode squeezing in the generated harmonic radiation, with a transition from Super-Poissonian to Poissonian photon statistics. The measured violation of the Cauchy-Schwarz inequality realizes a direct test of multipartite entanglement in high-harmonic generation.

In conclusion, semiconductor HHG is a new platform that can classically produce tailored structured light on nanometer and attosecond space/time scales. Furthermore, HHG can produce non-classical states of light with unique features such as multipartite broadband entanglement or multimode squeezing, a key resource for future quantum information technology.





From classical to quantum nature of high harmonic generation
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