Sistemas para manipulação quantica em estado solido / Towards an implementation of quantum manipulation in solid states
AUTOR(ES)
Thiago Pedro Mayer Alegre
DATA DE PUBLICAÇÃO
2008
RESUMO
This thesis proposes and implements a system for quantum information processing, focusing primarily on the associated instrumentation. The basic physical aspects for computation, such as the associated energy and Shannon s entropy, were revisited. InAs:GaAs quantum dots were elected as the physical system of choice for this implementation; in particular, the spin degree of freedom of the trapped electrons was utilized. Therefore, the electronic properties of the quantum dots, as well the g-tensor and the polarization degree, were investigated as a function of the temperature and magnetic field. It was possible to describe the electronic properties within the effective mass formalism, assuming a parabolic lateral confinement. Since the spin degree of freedom was elected as the basis for the quantum computation, a system for spin paramagnetic resonance was devised. The choice for not using a commercial system was made. Instead, a connectorized setup was designed, permitting the semiconductor material to be within a chip, and additionally allowing for focusing the microwave magnetic field above the device. Basically, this chip consisted of a half-wavelength microstrip cavity. A second microstrip cavity with two input ports was also designed to allow the arbitrary control of microwave polarization delivered to the sample. Finally, the quantum state read-out was demonstrated through an optical technique on Nitrogen-Vacancy complexes in diamond. The high sensitivity of the system allows for single spin detection. The selectivity for the optical and spin transitions was characterized and manipulated, using the resonant cavity experimental setup. As a perspective, experiments exploring integration issues on the system are shown
ASSUNTO(S)
linhas de transmissão em fita quantum dots qubit nitrogen-vacancy microstrip ressonancia paramagnetica eletronica nitrogenio-vacancia qubit pontos quanticos computação quantica quantum computation electron paramagnetic resonance
