ELFT HÍRADÓ

[<vera.horvath AT eli-alps.hu>]

Előadó: Varró Sándor (ELI ALPS, Wigner FK)
Cím: Multiphoton processes in the field of a ‘pedestal’

Időpont: 2022. március 18., 9 óra
Helyszín: ELI ALPS konferenciaterme, Szeged, Wolfgang Sandner utca 3.

Az előadás kivonata:
The high-intensity light pulses used in mutiphoton experiments come from
amplifiers, and these pulses contain quite strong (unwanted) pre-pulses, or
‘pedestals’. The main source of the pedestal is said to be the amplified
spontaneous emission (ASE) of the amplifying medium. Since the photon
statistics of the ASE is different from that of the main pulse, the study of
multiphoton processes taking place in a pedestal may be interesting, both in
theory and in experiments. This is even so, because in the last couple of
years there has been a growing activity in investigating how, and to what
extent the quantum nature of light manifest itself in strong-field laser-
matter interactions? It seems that quantum optical considerations will receive
an increasing importance in the interpretation of certain experimental results
on high-order processes, like quantum correlations and photon counting
measurements [1-5].
Recently we have worked out a general quantum optical theory of multiphoton
processes [6], which seems to be capable of answering the above question in
several cases. In the present talk we shall briefly explain the main
ingredients of this theory, and deal with the possible role of photon
statistics in high-harmonic generation. On the basis of this general theory
[6], and with the help of our new results on squeezing transitions [7], we
have also calculated the transition probabilities of electron excitation and
scattering in the field of a ‘pedestal’. The larger part of the talk will be
devoted to the discussion of the main characteristics of such multiphoton
processes.

References.
[1] Tsatrafyllis N, Kühn S, Dumergue M, Földi P, Kahaly S, Cormier E, Gonoskov
I A, Kiss B, Varjú K, Varró S and Tzallas P, Sub-cycle quantum electrodynamics
in strongly laser-driven semiconductors. Physical Review Letters 122, 193602
(2019).
[2] Gorlach, A.; Neufeld, O.; Rivera, N.; Cohen, O.; Kaminer, I. The quantum-
optical nature of high harmonic generation. Nat. Commun. 2020, 11, 4598.
[3] Lewenstein, M.; Ciappina, M.F.; Pisanty, E.; Rivera-Dean, J.; Lamprou, T.;
Tzallas, P. The quantum nature of light in high harmonic generation. (2020).
arXiv: 2008.10221.
[4] Földi P, Magashegyi I, Gombkötő Á and Varró S, Describing high-order
harmonic generation using quantum optical models. Photonics 2021, 8, 263.
(2021).
[5] Gombkötő Á, Földi P, Varró S, A quantum optical description of photon
statistics and cross-correlations in high harmonic generation. Physical Review
A 104, 033703 (2021).
[6] Varró S, Quantum optical aspects of high-harmonic generation. Photonics 8,
269 (2021) [https://doi.org/10.3390/photonics8070269 ].
[7] Varró S, Coherent and incoherent superposition of transition matrix
elements of the squeezing operator.  Journal of Physics Conf. Ser. (2022). E-
print: arXiv: 2112.08430 [quant-ph].

A szeminárium angol nyelvű.
Minden érdeklődőt szívesen látunk akár személyesen, akár online.
Link az online csatlakozáshoz:
https://teams.microsoft.com/l/meetup-join/19%3ameeting_NmIwODBjNjItODQ2Mi00ODljLWFmNWYtNzMyNTlmMDUyNmQ3%40thread.v2/0?context=%7b%22Tid%22%3a%22b207389a-c5cb-4cb0-a1ad-227b94e96448%22%2c%22Oid%22%3a%22ce4a2818-27b2-48f1-94cc-3fa41fc44303%22%2c%22IsBroadcastMeeting%22%3atrue%7d&btype=a&role=a