The structure and dynamics of liquids at very high temperature have been little explored because they are too hot to handle, difficult to contain, and chemically too aggressive to warrant the survival of most examination tools. Accordingly, containerless levitation techniques have been developed for such investigations. I will review some of the levitation techniques and outline their exotic advantages: (1) creating a “naked” very hot liquid to be investigated by different probes, (2) undercooling liquids down to several hundred degrees below their equilibrium freezing point and (3) exploring the domains of two co-existing liquids. A special attention will be given to levitation techniques combined with neutron and x-ray techniques as well as experimental results obtained on various materials.

Pseudoscalar particles are ubiquitous in models of New Physics and could mediate the interactions of dark matter with the visible sector. Although direct detection experiments are fairly inefficient in constraining such scenarios, they can be tested through a combination of collider, cosmological and astrophysical probes. I will discuss the interplay between these observables in a simple pseudoscalar-mediated dark matter model and comment upon how these constraints evolve within UV-complete New Physics scenarios. Time permitting, I will also briefly discuss alternative ideas about the generation of the dark matter abundance in the Universe which imply a radically different phenomenology at the LHC.

It is demonstrated that topological surface states (TSS) are all around a SnTe bulk sample. It is accomplished by measuring the Shubnikov-de Haas and the de Haas-van Alphen effects for a magnetic field tilted with respect to the [100] crystal direction. The oscillatory magnetization of TSS is calculated taking into account that the bulk SnTe provides a large reservoir of holes. A very good description of experiments is obtained.

In this talk, I will give an overview of recent advances and explicit calculations for the entropy of certain black hole solutions in four-dimensional supergravity theories. Exact results are made available for such black holes thanks to the Quantum Entropy Function formalism and supersymmetric localization, which I will review. Applying this method exhibits some striking connections between the exact entropy of supersymmetric black holes and the mathematics of modular and Jacobi forms. In particular, for the case of 1/4-BPS black holes in the N=4 theory, supergravity organizes the corrections to the area-law (or Bekenstein-Hawking entropy) in a number-theoretic way, and it can be argued that these corrections are related to the ones appearing in the study of mock modular forms.

This thesis deals with energy management in open quantum systems. Three different systems are under study in the limit of weak system–environment coupling, and their dynamics is described by Markovian quantum master equations. In the first part of the talk, the derivation of such equation is briefly discussed in a specific case, and several notions of quantum thermodynamics are introduced. In the second part, a quantum system embedded in an out-of-thermal-equilibrium electromagnetic field is investigated. It is composed of a three-level atom playing the role of an absorption quantum thermal machine, as well as N two-level atoms (‘qubits’), with N = 1, . . . , 6, which are the target bodies. It is demonstrated that the machine is able to perform significant thermal tasks on the qubits, even when their number is increased. Moreover, it is pointed out that due to qubit–qubit interactions, the tasks delivered by the machine are distributed throughout the system of interacting qubits, such that in some cases the temperature of the qubits which are completely decoupled from the machine can still be considerably affected by it. This task-distribution mechanism is investigated by means of the correlations between different subparts of the system. In addition, the tuning of thermal tasks is discussed. In the third part, energy transport is investigated along atomic chains (between 2 and 7 atoms) embedded in blackbody radiation around room temperature. It is shown that the transport efficiency can reach remarkable values, exceeding 100% and reaching 1400% in some configurations. Moreover, when the efficiency is amplified, the transport range is also considerably increased. Finally, the fourth part also deals with energy transport in atomic chains. The quantum system is located at the interface of a photonic topological insulator (PTI), supporting a unidirectional surface-plasmon-polariton (SPP) immune to backscattering. The SPP propagates along the chain and assists energy transport. Comparison is made between reciprocal and unidirectional SPPs in terms of transport efficiency, and it is shown that the latter can yield an efficiency larger by one order of magnitude. In addition, several practical aspects stemming from PTIs are highlighted, including the robustness of
energy transport in the presence of defects on the SPP path.

Thesis committee:
Mário G. SILVEIRINHA, Professeur associé, Université de Lisboa (Rapporteur)
Guido PUPILLO, Professeur, Université de Strasbourg (Rapporteur)
Angela VASANELLI, Professeur, Université Paris-Diderot (Examinatrice)
David DEAN, Professeur, Université de Bordeaux (Examinateur)
Mauro ANTEZZA, Maître de conférence, Université de Montpellier (Directeur de thèse)
Riccardo MESSINA, Chargé de recherche, Université de Montpellier (Co-encadrant)