Estudo da primeira lei da termodinâmica para um sistema quântico de dois níveis acoplado com um ambiente térmico

Abstract

In this dissertation, a review of the concepts of quantum mechanics is presented, dealing with two-level systems (qubits) as part of a composite system, using the density matrix formalism. Using the method of Kraus operators, we study the evolution of systems subject to noise caused by the environment, such as in the case of the generalized amplitude damping channel. In order to be able to analyze the information obtained, a general review of Shannon and von Neumann entropies and their properties is made. A quantum view of thermodynamics is also presented, emphasizing the first and second laws of classical thermodynamics. The study focuses on studying the energetic processes that occur when a qubit is coupled to a thermal environment. The evolution of the composite system is described through a unitary transformation, and the thermodynamic properties of the qubit are analyzed through a more general definition of the first law of quantum thermodynamics, in which the role of quantum coherence is highlighted.