Efeitos térmicos em fotodiodos de pontos quânticos semicondutores

• Ano de defesa: 2012
• Autor(a) principal: Assunção, Maryzaura de Oliveira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Uberlândia; BR; Programa de Pós-graduação em Física; Ciências Exatas e da Terra; UFU
• Palavras-chave em Português: Pontos quânticos; Fotocorrente; Funções de Green; Efeitos térmicos; Oscilações de Rabi; Green, Funções de; Oscilações; Quantum dots; Photocurrent; Green s functions; Thermal effects; Rabi oscillations; CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: https://repositorio.ufu.br/handle/123456789/15650; https://doi.org/10.14393/ufu.di.2012.315

The recent progress in the manufacturing of semiconductor quantum dots (QD) systems has made possible the coherent control of quantum states in QDs using optical or electrical techniques. Laser pulses have been recently used to coherently coponto quânticontrol the exciton population in QDs. The coherent manipulation of quantum states is a high priority task to the development of quantum information and quantum computation. One particular signature of coherency in quantum systems is the Rabi oscillations, which were recently observed in a few experimental works. Here we theoretically study a system composed of a semiconductor QD, tunnel coupled to electron reservoirs. In the presence of a laser field an electron-hole pair is created in the QD. An external source-drain (bias) voltage allows electrons and holes to tunnel to the reservoirs. The study was developed via the non-equilibrium Green s function technique. We solve numerically a set of coupled differential equations to the retarded and lesser Green functions. This gives the occupation probabilities of the two levels of the QD and the laserinduced photocurrent as a function of time. We focus our attention on the effects of temperature on the Rabi oscillations. Our main findings encompass a thermal activated Pauli blockade of the Rabi oscillations that can be controlled via the reservoirs temperature. We also discussed the effects of this thermal activation of Pauli blockade on the photocurrent. These results suggest that ability to measure temperatures via quantum coherent signals, thus suggesting the possibility of a new quantum-dot based thermometer.