Előadó: Varró Sándor (Wigner FK SZFI, ELI-ALPS)
Előadás címe: Displacement and squeezing transitions in very-high-order multiphoton processes
Dátum: Tuesday, 8 March 2022, 10:00
Helyszín: Bldg 1, auditorium, https://wigner-hu.zoom.us/j/92490328041?pwd=aW9tT005N3JDSWNXcFNrTUZHNUt… Meeting ID: 924 9032 8041 Passcode: 211664
Összefoglaló:
In many recent investigations on light-matter interactions the theorist should possibly use exact solutions of the equations of motion, since perturbation theory does not give satisfactory agreement with the experiments. In quantum electrodynamics and in quantum optics, at the most fundamental level, the equations of motion contain linear and quadratic interaction terms. These terms can often be eliminated by performing the displacement and/or squeezing transformation. On the basis of such a technique, recently we have built up a general scheme for treating very-high-order multiphoton processes, like high-harmonic generation [1]. The transition probabilities are determined by the matrix elements (between photon number eigenstates) of the displacement and squeezing operators, which have to be superimposed according to the photon statistics of the inducing field. In the course of this study, it was a surprise for us that in the enormous literature on 'non-classical states and squeezing', which has accumulated during the last more than eight decades, the matrix elements of the squeezing operator (a special generator of Bogoliubov transformations) have not been published in a compact and usable, classical polynomial form. Recently, we have derived such a compact expression in terms of Gegenbauer polynomials [2], and we have used it to describe the effect of photon statistics on various quantum transitions. Among some illustrative applications of our analytical results, we shall discuss the multiphoton excitations in the field of a 'pedestal' (or 'pre-pulse') stemming from amplified spontaneous emission from a parametric amplifier.
[1] Varró S, Quantum optical aspects of high-harmonic generation. Photonics 8, 269 (2021). [https://doi.org/10.3390/photonics8070269 ].
[2] Varró S, Coherent and incoherent superposition of transition matrix elements of the squeezing operator. J. Phys. Conf. Ser. (2022). E-print: arXiv: 2112.08430 [quant-ph].
Language of the talk: English
