Title: PT-symmetric systems in the quantum regime
Other Titles: PT Symmetriebrechung in Quantensytemen
Language: English
Authors: Huber, Julian 
Qualification level: Diploma
Advisor: Rabl, Peter 
Issue Date: 2016
Huber, J. (2016). PT-symmetric systems in the quantum regime [Diploma Thesis, Technische Universität Wien]. reposiTUm. https://doi.org/10.34726/hss.2016.32662
Number of Pages: 79
Qualification level: Diploma
The phenomenon of PT-symmetric breaking in classical systems with balanced loss and gain is associated with a sharp transition from a purely real to complex eigenvalue spectrum of the underlying dynamical matrix. Over the past years this phenomenon has been extensively studied, for example, using coupled optical modes, where however, the system is always in a large amplitude classical state. In this thesis we study for the first time the effect of PT-symmetry breaking in the quantum regime where the effects of non-linearities and intrinsic quantum noise become important. In the first part we analyze the stationary states of two coupled harmonic oscillators with engineered loss and gain. By applying different numerical techniques to solve the corresponding master equation for this system we observe an unconventional transition from a high-noise symmetric state to a parity-broken lasing state with strongly reduced fluctuations. Moreover, we show that the transition point strongly depends on the quantumness of the system. In the second part we develop numerical techniques for the simulation of extended PT-symmetric spin chains, which we use to demonstrate a crossover from a symmetric to a symmetry broken phase also for finite dimensional quantum systems.
Keywords: Quantenoptik; dissipative Quantensysteme
quantum optics; open quantum systems
URI: https://doi.org/10.34726/hss.2016.32662
DOI: 10.34726/hss.2016.32662
Library ID: AC13285293
Organisation: E141 - Atominstitut 
Publication Type: Thesis
Appears in Collections:Thesis

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