Dynamical detection of dipole-dipole interactions in dilute atomic gases

Abstract: Recent experiments study the dipole-dipole interaction in extremely dilute, thermal atomic vapors using optical spectroscopy. At such densities, the atoms are coupled only very weakly, which makes the detection of signatures of their interaction an experimental challenge. To discriminate collective effects from an intense single-scattering background, these experiments employ ultrafast spectroscopies. To this end, ultrafast spectroscopy is useful because it can separate the total fluorescence intensity from a sample into contributions from the factorizing single-atom response and signals that arise from interacting atoms, by virtue of their different dependence on the phase of the classical driving fields. The interpretation of the spectroscopic signals requires a firm theoretical understanding of the scattering dynamics in the cloud. Otherwise, a reliable attribution of the extracted signal to interaction effects rather than to single-atom responses is impossible.

Thus, we will here situate these experiments at the interface between two fields: ultrafast spectroscopy on the one hand, which is typically employed to study signals that originate from ensembles uncoupled scatterers with a rich internal structure, such as biological molecules, and the physics of multiple scattering of light in dilute atomic clouds on the other hand, which has been studied extensively at very low temperatures in the weak-localization regime.

In this thesis, we take first steps at reconciling the theoretical foundations and methods of both fields. We adapt a quantum optical open system treatment, which was used before to study the steady state of photon scattering, to the inherently time-dependent spectroscopic technique. Fully analytical results for the fluorescence signals are obtained, which enable a deeper understanding of the spectroscopic signals in terms of the exchange of transverse photons, i.e. the retarded dipole-dipole interaction. We verify the analytical procedure through a numerical simulation.

Our model captures the qualitative results of the experiments, and yields a rough quantitative agreement of relative signal strengths. We use our insight into the radiative processes to review ambiguities that emerged in the discussion of the experimental works

Angaben zum Objekt

• Standort: Deutsche Nationalbibliothek Frankfurt am Main
• Umfang: Online-Ressource
• Ausgabe: Revised version, 3. May 2021
• Sprache: Englisch
• Anmerkungen: Universität Freiburg, Masterarbeit, 2021

Klassifikation und Themen

• Schlagwort: Quantenoptik

Beteiligte, Orts- und Zeitangaben

• Ereignis: Veröffentlichung
• (wo): Freiburg
• (wer): Universität
• (wann): 2021
• Urheber: Ames, Benedikt
• Beteiligte Personen und Organisationen: Buchleitner, Andreas ; Carnio, Edoardo ; Shatokhin, Vyacheslav N.

Weitere Informationen

• DOI: 10.6094/UNIFR/194824
• URN: urn:nbn:de:bsz:25-freidok-1948242
• Rechteinformation: Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Letzte Aktualisierung: 25.03.2025, 13:55 MEZ