Please use this identifier to cite or link to this item: https://scholarbank.nus.edu.sg/handle/10635/235776
Title: (A) REDUCED DENSITY MATRIX GENERATION ALGORITHMS IN SINGLE-PARTICLE-EXACT DENSITY FUNCTIONAL THEORY, (B) QUANTUM DYNAMICAL SIMULATION OF A TRANSVERSAL STERN-GERLACH INTERFEROMETER, (C) OPEN QUANTUM SYSTEM PROCESS TOMOGRAPHY
Authors: MIKOLAJ PARANIAK
ORCID iD:   orcid.org/0000-0003-1713-4032
Keywords: density functional theory, stern--gerlach interferometer simulation, open quantum dynamics, quantum process tomography, single-particle-exact DFT
Issue Date: 19-Aug-2022
Citation: MIKOLAJ PARANIAK (2022-08-19). (A) REDUCED DENSITY MATRIX GENERATION ALGORITHMS IN SINGLE-PARTICLE-EXACT DENSITY FUNCTIONAL THEORY, (B) QUANTUM DYNAMICAL SIMULATION OF A TRANSVERSAL STERN-GERLACH INTERFEROMETER, (C) OPEN QUANTUM SYSTEM PROCESS TOMOGRAPHY. ScholarBank@NUS Repository.
Abstract: (A) A central problem arising in single-particle-exact density functional theory is the generation of reduced single-particle density matrices from a suitable class. We present one solution to this problem, prove its correctness and discuss its applications. (B) We revisit the question of the reversibility of the Stern--Gerlach apparatus. In the original proposal, evolution of an atomic beam split by the Stern--Gerlach apparatus was to be reversed by placing suitably oriented magnets, generating a reverse magnetic field. Previous theoretical works showed that this is difficult to accomplish experimentally. We supplement theoretical insights with an exact wave function simulation of the transversal Stern--Gerlach interferometer dynamics, presenting firm evidence in favor of its fundamental irreversibility. (C) We study the problem of characterizing the dynamics of an open quantum system. We model the system-environment dynamics with a time-discretized, joint evolution channel, developing an extension of quantum state tomography to characterize relevant parts of the environment influencing the system, in a simplified scenario where the joint evolution channel is known. In the general case, when nothing is known about the system-environment interaction, we develop a numerical scheme to characterize the effective evolution of the system under the influence of noise.
URI: https://scholarbank.nus.edu.sg/handle/10635/235776
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