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Bertacco, Giovanni Francesco (2018) Functional integration methods for Rabi-coupled quantum gases. [Magistrali biennali]

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In the first part of the thesis we investigate properties of multicomponent quantum Bose gas with a Rabi coupling, using theoretical methods based on functional integration. At very low temperatures beyond-mean-field contribution crucially affect the equation of state of many-body systems. We derive the equation of state of the gas including the quantum fluctuations. The divergent zero-point energy of gapless and gapped elementary excitations of the uniform system is properly regularized obtaining a meaningful analytical expression for the beyond-mean-field equation of state in the weak Rabi coupling approximation. In the case of attractive inter-particle interaction we show that the quantum pressure arising from Gaussian fluctuations can prevent the collapse of the mixture with the creation of a self-bound droplet. In the second part we study the effects of Rabi coupling along the BCS-BEC crossover of a Feshbach resonance for a two-spin-component Fermi gas. Results such as the gap equation, the number equation and the critical temperature in the mean-field approximation have been obtained. In the last part we include quantum fluctuations contributions in the previous calculations in order to investigate the phase diagram of the system.

Item Type:Magistrali biennali
Corsi di Diploma di Laurea:Scuola di Scienze > Fisica
Uncontrolled Keywords:Functional-integration, Rabi-coupling, ultracold-atoms, quantum-gas
Subjects:Area 02 - Scienze fisiche > FIS/03 Fisica della materia
Codice ID:61176
Relatore:Salasnich, Luca
Correlatore:dell'Anna, Luca
Data della tesi:September 2018
Biblioteca:Polo di Scienze > Dip. Fisica e Astronomia "Galileo Galilei" - Biblioteca
Tipo di fruizione per il documento:on-line per i full-text

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