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oai:recercat.cat:2117/3282192026-01-18T05:32:29Zcom_2072_1033col_2072_452950

The imaginary part of the high-harmonic cutoff Pisanty, Emilio Ciappina, Marcelo F. Lewenstein, Maciej Àrees temàtiques de la UPC::Física Radiation high-harmonic generation Radiació High-harmonic generation the emission of high-frequency radiation by the ionization and subsequent recombination of an atomic electron driven by a strong laser eld is widely understood using a quasiclassical trajectory formalism, derived from a saddle-point approximation, where each saddle corresponds to a complex-valued trajectory whose recombination contributes to the harmonic emission. However, the classi cation of these saddle points into individual quantum orbits remains a high-friction part of the formalism. Here we present a scheme to classify these trajectories, based on a natural identi cation of the (complex) time that corresponds to the harmonic cuto . This identi cation also provides a natural complex value for the cuto energy, whose imaginary part controls the strength of quantum-path interference between the quantum orbits that meet at the cuto . Our construction gives an e cient method to evaluate the location and brightness of the cuto for a wide class of driver waveforms by solving a single saddle-point equation. It also allows us to explore the intricate topologies of the Riemann surfaces formed by the quantum orbits induced by nontrivial waveforms. Peer Reviewed Postprint (published version) 2020-07-22 Article Pisanty, E.; Ciappina, M.F.; Lewenstein, M. The imaginary part of the high-harmonic cuto. "Journal of Physics: Photonics", 22 Juliol 2020, vol. 2, núm. 34013, p. 1-21. https://hdl.handle.net/2117/328219 10.1088/2515-7647/ab8f1e eng https://iopscience.iop.org/article/10.1088/2515-7647/ab8f1e FIS2016-79508-P info:eu-repo/grantAgreement/MINECO//SEV-2015-0522/ES/AGR-INSTITUTO DE CIENCIAS FOTONICAS/ info:eu-repo/grantAgreement/EC/H2020/833801/EU/NOvel Quantum simulators – connectIng Areas/NOQIA IU16-011424 info:eu-repo/grantAgreement/AEI/Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020/PCI2019-111828-2/ES/SIMULADOR CUANTICO DE ATOMO MAGNETICO/ 10.13039 501100011033 http://creativecommons.org/licenses/by-nc-nd/3.0/es/ Open Access Attribution-NonCommercial-NoDerivs 3.0 Spain 21 p. application/pdf IOP