title: Emergent phenomena in two-dimensional Fermi systems
creator: Anantha Murthy, Puneet
subject: ddc-530
subject: 530 Physics
description: In this thesis, I present the experimental exploration of emergent effects in a twodimensional gas of ultracold atoms. First, I describe a novel method to measure the momentum distribution of a strongly interacting gas. Using this technique, we map out the phase diagram of the 2D BEC-BCS crossover and measure the critical temperature for  superfluidity. We observe, for the first time, the Berezinskii–Kosterlitz–Thouless phase transition in a Fermi gas that is characterized by algebraic decay of phase correlations. In a second experiment, we investigate fermion pairing in the normal phase using radio-frequency spectroscopy. We observe a crossover from two-body to many-body pairing at remarkably high temperatures, thus answering  a long-standing question concerning the existence of a pseudogap in this system. In the next experiment, we address the question of scale-invariance breaking, also known as a quantum anomaly, in the dynamics of a 2D Fermi superfluid. We observe a striking manifestation of this quantum anomaly in the momentum-space dynamics of the system, which demonstrates that short-range fermionic interactions have a  strong influence on long-range coherence in the system. By revealing the intriguing effects emerging from the interplay between fermionic statistics, strong interactions and reduced dimensionality, this thesis advances our general understanding of many-body quantum systems.
date: 2018
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/24730/1/PMThesis_FINAL_PRINT.pdf
identifier: DOI:10.11588/heidok.00024730
identifier: urn:nbn:de:bsz:16-heidok-247303
identifier:   Anantha Murthy, Puneet  (2018) Emergent phenomena in two-dimensional Fermi systems.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/24730/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng