000087476 001__ 87476
000087476 005__ 20200120113927.0
000087476 037__ $$aTAZ-TFG-2019-2465
000087476 041__ $$aeng
000087476 1001_ $$aRomán Roche, Juan
000087476 24200 $$aEffective theories for the light-matter ultrastrong coupling regime
000087476 24500 $$aTeorías efectivas para el acoplo ultrafuerte entre luz y materia
000087476 260__ $$aZaragoza$$bUniversidad de Zaragoza$$c2019
000087476 506__ $$aby-nc-sa$$bCreative Commons$$c3.0$$uhttp://creativecommons.org/licenses/by-nc-sa/3.0/
000087476 520__ $$aThis End-of-Degree Thesis is structured as follows: In Section 1, we briefly show how the linear cavity array with coupled qubits naturally leads to the spin-boson model, we also analyse the motivation behind the introduction of the Polaron Transform for the study of said model. In Section 2 we apply the PT to a single-qubit system in order to assert its superiority over the RWA in the USC regime. We benchmark it using exact diagonalisation in small-sized systems and characterise both the GS and spontaneous emission. In Section 3 we present a generalisation of the PT for the two-qubit model and apply it successfully, proving that it converges to the single qubit scenario for sufficiently distant qubits. We show that the two-qubit system presents a ferromagnetic Ising ground state, as well as bound excited states that can be described using a simple tight-binding model, and serve as the basis for a proposed lossless state-transfer protocol. Finally, we draw some conclusions from our results and outline possible continuations. Technical details are left for the Appendix, including a link to a public repository where all the code, originally developed for this project, can be found.<br />
000087476 521__ $$aGraduado en Física
000087476 540__ $$aDerechos regulados por licencia Creative Commons
000087476 700__ $$aZueco Láinez, David$$edir.
000087476 7102_ $$aUniversidad de Zaragoza$$bFísica de la Materia Condensada$$cFísica de la Materia Condensada
000087476 8560_ $$f717281@celes.unizar.es
000087476 8564_ $$s185877$$uhttps://zaguan.unizar.es/record/87476/files/TAZ-TFG-2019-2465_ANE.pdf$$yAnexos (eng)
000087476 8564_ $$s4656048$$uhttps://zaguan.unizar.es/record/87476/files/TAZ-TFG-2019-2465.pdf$$yMemoria (eng)
000087476 909CO $$ooai:zaguan.unizar.es:87476$$pdriver$$ptrabajos-fin-grado
000087476 950__ $$a
000087476 951__ $$adeposita:2020-01-20
000087476 980__ $$aTAZ$$bTFG$$cCIEN
000087476 999__ $$a20190627151039.CREATION_DATE