Tomografia de estados de pares de fótons Stokes e anti­Stokes oriundos do espalhamento inelástico de luz no diamante e violação de desigualdade de Bell

• Ano de defesa: 2023
• Autor(a) principal: Tiago Abreu Freitas
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; Brasil; ENG - DEPARTAMENTO DE ENGENHARIA ELÉTRICA; Programa de Pós-Graduação em Engenharia Elétrica; UFMG
• Palavras-chave em Português: Informação quântica; Espalhamento Raman; Correlação Stokes e anti- Stokes; Emaranhamento; Engenharia elétrica; Raman, Efeito de
• Link de acesso: http://hdl.handle.net/1843/63539

The last decades have been marked by intense research on the evolution of computer and communication systems. Within this context, quantum computing has been one of the areas that generated large interest and effort from researchers due, to the immense potential offered. Quantum information research has been through numerous evolutionary stages, and photonic transport is one of the most promising methods for information processing. Within the context of the use of photons for information transportation, Raman spectroscopy, which consists of an optical spectroscopy technique based on the inelastic scatter of light, where the scattered photons carry information from the vibration structure of the medium, is presented as an exciting way for coding and transportation of quantum information. In this work, we explore the phenomenon of correlated Stokes- anti-Stokes (SaS) Raman scattering, analyzing the quantum character of the phenomenon. The implementation of the experimental apparatus was performed for the measurement of the correlation of the photons generated in this phenomenon in diamond, confirming its quantum character and optimizing the phenomenon for a complete analysis of the process in order to confirm that besides being correlated, the pair of SaS photons would also be entanglement. Initially, we studied the dependence on phenomenon efficiency with different lasers (continuous, ps, and fs pulsed, and different wavelengths) and the dependence on the correlation function with the Raman shift. These studies have shown that the best configuration for the study regarding the possible entanglement of the process would be using the fs laser in 785nm. In the following steps, state tomography measurements were performed to completely characterize the polarization state of the SaS pair. During this study, it was possible to observe the influence of the crystallographic orientation of the diamond on the SAS polarization state, which directly influences the generation of entanglement. Finally, Bell’s inequality measurements of the CHSH type were performed to confirm the entanglement in polarization of the SaS state.