NON EQUILIBRUM QUANTUM INFORMATION-THERMODYNAMICS : THEORY AND PHOTONIC SIMULATIONS

Abstract

The assertion information, rather than being an abstract notion, is entirely a physical quantity has fostered tantalizing exertions to find behaviours outside the remit of conventional thermodynamics. Many efforts have been given to refine technology for quantum computing, and enhance thermodynamic effi ciencies of refrigerators and heat engines in the quantum regime. Despite em bodying a tempting avenue for theoretical insight and technological progress, the field of quantum information-thermodynamics is however far from being a fully developed framework. In the set of key missing grounds, the lack of a self-consistent formulation of irreversibility at the quantum level, and a more pronunced matching between theory and experiments represent one of the cen tral issues to be solved. This thesis aims at bridging some of these aspects by inspecting specific non-equilibrium thermodynamic phenomena through the identification of figures of merit which can be grasped experimentally. Au fond, the investigation has been addressed towards three principal topics covering the dynamical properties of quantum states during thermalization, quantum measurements, and quantum simulation: the latter naturally encapsulate most of the scenarios conceived in the current state of art. Thermalizing dynamics of quantum systems have been shown to be prominent testbeds to assess the way extremely thermodynamic peculiarities are influenced by quantum quirks when approaching their equilibrium configurations: the attention has been de voted to the investigation of single-qubit thermalization dynamics through the introduction of methods able to uncover some profound implications of Lan dauer’s principle. A clear example of this is represented by the exploitation of geometrical tools able to bridge different aspects concerning the thermal ization speed of evolution, irreversibility, and the erasure of information. The common ground shared by information and thermodynamics has pushed the attention towards quantum measurements topics where exertions aimed at de terminin the minimal thermodynamic cost for their realization have been fo cused. The wide spectrum of available quantum measurements have been also investigated from a different point of view which is based on aspects lying at the heart of quantum mechanics. The theoretical efforts in acquiring experi mentally suitable figures of merit has strongly motivated the design of experi mental setups able to simulate the considered dynamics, and to investigate the information-thermodynamics of fundamental quantum processes. Photonic based platforms have been demonstrated to be particularly valid for such a purpose, as they pledge the high degrees of control required for experimental satisfactory studies of quantum information-thermodynamics.