Josef Rammensee

Semiclassical Treatment of Interference Phenomena in Bosonic Quantum Many-Body Systems

Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften (Dr. rer. nat.) der Fakultät für Physik der Universität Regensburg.
The major goal of the semiclassical theory is to understand and treat quantum systems in the re-gime of large quantum numbers using information from its corresponding classical limit. Here, quantum phenomena can be addressed through a path integral perspective, i.e. the weighted in-terference of phases accumulated along classical trajectories. While this formalism has successfully explained interference phenomena in, for instance, mesoscopic quantum single-particle systems, recent extensions of the semiclassical approach allow now to tackle interacting quantum many-body systems.

This thesis contributes to the ongoing series of applications of semiclassical techniques to bosonic quantum many-body systems. Its first topic deals with the out-of-time-order correlator (OTOC), the expectation value of the squared commutator of two local operators at different times, which can directly probe the presence of chaos in the classical limit of a quantum many-body system. This work presents a comprehensive theoretical analysis of the dynamical behavior of the OTOC and highlights its connection to the key properties defining classical chaos. The second topic considers the coherent transport of cold bosonic atoms through an Aharonov-Bohm ring structure with a dis-order potential. For such systems, it is well known that non-interacting particles display Al'tshuler-Aronov-Spivak oscillations in the disorder-averaged transmission probability as a function of the encircled flux. Including interaction, numerical studies indicate an inversion of peaks seen in the profile of the oscillations, for which this thesis provides a semiclassical understanding.
Beigaben:div. Grafiken
Einbandart:Broschur klebegebunden
Format:17 x 24 cm
Gewicht:465 g
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