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Identifier

000449133

Title

Enhanced optical cross section, superradiance and subradiance from strongly interacting atoms

Alternative Title

Ενισχυμένη οπτική διατομή, υπερακτινοβολία και υποακτινοβολία από έντονα αλληλεπιδρώντα άτομα

Author

Τζήμκας-Δακής, Φίλιππος Χ.

Thesis advisor

Petrosyan, David

Reviewer

Κομίνης, Ιωάννης
Μακρής, Κωνσταντίνος

Abstract

This thesis lies in the broader area of Quantum Optics. The subject focuses in the radiation properties of atomic ensembles with subwavelength interatomic distances driven by coherent laser radiation and strongly interacting with each other via the free-space dipole-dipole interaction. We study large two-dimensional arrays of atoms under the single excitation approximation, exploring their collective behavior with enhanced effective cross section for interaction with light. We then suggest ways of exploiting collective atomic response to create mirrors, lenses and deflectors for weak beams of light. We developed a numerical method to efficiently describe the many-body dissipative system of closely-spaced atoms using a Monte-Carlo stochastic wavefunction approach adapted to account for cooperative decay of multiply-excited states of the system. We apply this method to various geometries of atomic positions in order to study superradiant and subradiant emission of the photons and calculate their correlations revealing the photon bunching and anti- bunching. To better understand the laser-excitation spectrum of the system and the correlations of the emitted photons, we diagonalize the effective non-Hermitian Hamiltonian and deduce the various excitation and collective decay paths that the system explores during the continuous driving. Our studies are relevant to the recent quest to tailor the cooperative radiative properties of periodic arrays of atoms serving as phased-array optical antennas with unique properties, including the highly efficient and directional photon emission, absorption and reflection. But in order to go beyond the previous studies, we do not truncate the Hilbert space of the system to a single or a few- excitation sub-space, which permits us to reveal the non-linear regime of the cooperative atom-light interaction.

Language

English

Subject

Atomic array

Atomic lens

Atomic mirror

Density matrix

Dipole dipole interaction

Monte carlo

Αλληλεπίδραση διπόλου-διπόλου

Διατομή σκέδασης

Κάτοπτρο ατόμων