The thesis is devoted to applications of the anti de Sitter/Conformal field theory correspondence (AdS/CFT, also called holography) to various problems in different areas of theoretical physics. We... Show moreThe thesis is devoted to applications of the anti de Sitter/Conformal field theory correspondence (AdS/CFT, also called holography) to various problems in different areas of theoretical physics. We make use of AdS/CFT to get insights into the physics of superconductors, quark-gluon plasma, and to study properties of quantum field theories on non-causal backgrounds. In the first part of the thesis we construct a holographic model of a Bardeen-Cooper-Schrieffer-like superconductor and demonstrate that the Cooper instability of Fermi-liquids can be naturally described in holographic terms. We show that both the superconducting phase and the BEC/BCS crossover appear naturally. In the second part we address the problem of quark-gluon plasma formation in heavy ion collisions. We study the effect of finite chemical potential on this process and calculate physical properties of the resulting deconfined state. The third part is dedicated to study of evolution of a quantum system with violated causality. Using AdS/CFT we can map the complicated and poorly defined non-causal quantum dynamics onto a classical spacetime with closed timelike curves. Doing that we have derived the Green's function of the QFT and demonstrated that evolution of a quantum system can be consistent and non-pathological even at broken causality. Show less
Topological superconductors are a novel type of superconductors that carry Majorana particles at their boundary. These surface states are equal superpositions of electrons and holes, and hence are... Show moreTopological superconductors are a novel type of superconductors that carry Majorana particles at their boundary. These surface states are equal superpositions of electrons and holes, and hence are their own anti-particles. There has been a recent surge of theoretical and experimental effort to realize these special particles in the lab. While first observations support the theoretical predictions, fail-safe experimental evidence for Majoranas is still needed. Part of the challenge is that due to their vanishing charge they are not easily detected electrically. The topic of this thesis is the proposal and study of electrical signatures of Majoranas that are present in spite of their charge neutrality. By applying scattering and random matrix theory we first examine their generic properties. With the tool of numerical simulations we then put our predictions to test on realistic systems. Show less
We investigate the detection mechanism in superconducting single photon detectors via quantum detector tomography. We find that the detection event is caused by diffusion of quasiparticles from the... Show moreWe investigate the detection mechanism in superconducting single photon detectors via quantum detector tomography. We find that the detection event is caused by diffusion of quasiparticles from the absorption spot, combined with entrance of a vortex. Moreover, we investigate the behaviour of superconducting single photon detectors in an external magnetic field. Show less
