Banca de DEFESA: CARLOS HENRIQUE DA SILVA VIEIRA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : CARLOS HENRIQUE DA SILVA VIEIRA
DATE: 15/12/2023
TIME: 08:30
LOCAL: Online
TITLE:

Experimental Investigations on Fluctuations, Uncertainties and Limits in Quantum Thermodynamics

PAGES: 150
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUBÁREA: Física Geral
SUMMARY:

Currently, we are witnessing the emergence and accelerated development of the era known as NISQ (Noisy Intermediate-Scale Quantum Technologies), in which quantum computers, quantum communication systems, and quantum sensors begin to be commercialized and attract large governments and corporations. On the other hand, thermodynamics establishes fundamental limits to the operating regimes and energy exchanges in different technologies, including technologies emerging from quantum theory. In the latter case, non-equilibrium dynamics, energy fluctuations, and randomness are present and play a fundamental role.
The area of research that has focused on these topics from both a theoretical and experimental point of view has been called Quantum Thermodynamics. Modern techniques for manipulating quantum systems allow us to experimentally access microscopic states and individual systems, explaining the role of information theory in different protocols, in addition to introducing new and perspectives to experimental techniques and possible technological applications. In this context, for example, it is possible to create different flavors of Maxwell's demons in the laboratory and explore the role of quantum coherence and non-classical correlations in carrying out processes that would be impossible in the classical scenario (related to the so-called quantum advantage).
In small non-equilibrium quantum systems, quantities such as work, heat and entropy production acquire a stochastic character and are associated with probability distributions governed by fluctuation theorems or relations. In this thesis, we present some original experimental contributions to the area of quantum thermodynamics using spin qubits in nuclear magnetic resonance (NMR). The first contribution focuses on verifying detailed fluctuation theorems in a quantum setting that has a control and feedback process. Although there are theoretical studies regarding these relationships, to the best of our knowledge, our work represents the first experimental verification of such relationships in the quantum regime. The second contribution focuses on experimentally testing the robustness of a set of inequalities, which establish connections between the fluctuations of thermodynamic quantities and entropy production during a given protocol, known as thermodynamic uncertainty relations (TURs). In this case we consider again a process involving control and feedback. Finally, we present an experimental investigation regarding Nernst's heat theorem, related to a formulation of the third law and the limits imposed by thermodynamics for initializing a quantum device in its fundamental state. We argue that consequences arising from the limits imposed by the third law should have a substantial impact on the development of new quantum technologies and need to be addressed in future investigations.

We hope that the results developed in this thesis add some contribution to advance our understand about energy fluctuations and limits imposed by the thermodynamic description of systems in the quantum regime.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1544235 - ROBERTO MENEZES SERRA
Membro Titular - Examinador(a) Interno ao Programa - 3065679 - BRENO MARQUES GONCALVES TEIXEIRA
Membro Titular - Examinador(a) Externo à Instituição - CAMILLE LOMBARD LATUNE
Membro Titular - Examinador(a) Externo à Instituição - ROBERTO SILVA SARTHOUR JUNIOR - CBPF
Membro Titular - Examinador(a) Externo à Instituição - THIAGO RODRIGUES DE OLIVEIRA - UFF
Membro Suplente - Examinador(a) Interno ao Programa - 1838185 - FERNANDO LUIS DA SILVA SEMIAO
Membro Suplente - Examinador(a) Externo à Instituição - NORTON GOMES DE ALMEIDA - UFG
Membro Suplente - Examinador(a) Externo à Instituição - SÉRGIO RICARDO MUNIZ - USP