GTIIT-STU optics seminar

Title: Spontaneous Emission Phenomena studied by the Complex Scaling Method of Nonhermitian Quantum Mechanics

Speaker: Prof. Milan Šindelka

Chemistry Department, GTIIT

Abstract

Spontaneous emission (SE) is usually treated theoretically by employing the master equation approach of quantum dissipation theory of open systems. In this talk, another compelling viewpoint of SE will be highlighted. Namely, the SE will be interpreted as decay of a Feshbach type resonance of quantum scattering theory. Scattering resonances belong into the domain of Nonhermitian Quantum Mechanics (NHQM), and their properties are often studied by taking advantage of the Complex Scaling Method (CS). NHQM formulation of the SE problem requires an adequate implementation of the CS on momenta of the outgoing photons (emitted due to SE). The underlying mathematical formulation will be sketched in the first part of the presentation.

The second part will focus on application of the above mentioned NHQM formalism on the problem of a quantum harmonic oscillator coupled to an electromagnetic bath in the dipole approximation. An analytic nonperturbative NHQM solution of the corresponding SE problem will be presented, based upon the concept of nonhermitian normal modes.

The third part will futher extend the developed formalism on an intriguing problem of SE from electronic autoionizing metastable states. A novel NHQM approach will be presented, enabling an unified cohesive treatment of the SE phenomenon competing with the ionization phenomenon.

[1] Spontaneous Emission from Electronic Metastable Resonance States

Amir Sivan, Milan Šindelka, Meir Orenstein, and Nimrod Moiseyev, Phys. Rev. Lett. 135, 163001 (2025)

[2] Spontaneous emission from nonhermitian perspective: Complex scaling of the photon coordinates

Milan Šindelka and Daniel Šimsa, Molecular Physics 117, 1989 (2019).