Teorías efectivas para el acoplo ultrafuerte entre luz y materia

Román Roche, Juan
Zueco Láinez, David (dir.)

Universidad de Zaragoza, CIEN, 2019
Departamento de Física de la Materia Condensada, Área de Física de la Materia Condensada

Graduado en Física

Resumen: This End-of-Degree Thesis is structured as follows: In Section 1, we briefly show how the linear cavity array with coupled qubits naturally leads to the spin-boson model, we also analyse the motivation behind the introduction of the Polaron Transform for the study of said model. In Section 2 we apply the PT to a single-qubit system in order to assert its superiority over the RWA in the USC regime. We benchmark it using exact diagonalisation in small-sized systems and characterise both the GS and spontaneous emission. In Section 3 we present a generalisation of the PT for the two-qubit model and apply it successfully, proving that it converges to the single qubit scenario for sufficiently distant qubits. We show that the two-qubit system presents a ferromagnetic Ising ground state, as well as bound excited states that can be described using a simple tight-binding model, and serve as the basis for a proposed lossless state-transfer protocol. Finally, we draw some conclusions from our results and outline possible continuations. Technical details are left for the Appendix, including a link to a public repository where all the code, originally developed for this project, can be found.

Tipo de Trabajo Académico: Trabajo Fin de Grado