The Dynamics Of A Double-dot Charge Qubit Embedded In A Suspended Phonon Cavity

Nowadays, a great deal of attention is focused on the study of quantum infor-mation science and physical implementation of quantum computation. Among thevarious proposals and schemes, a promising candidate is the solid-state qubit basedon a single or more electrons in a semiconductor double quantum dot. According tothe hot issue, we theoretically investigate the dynamics of a double dot charge qubitthat is embedded inside a suspended semiconductor slab. To solve the Hamiltonianof the system, we use a perturbation treatment based on a unitary transformation withwhich more accurate results can be achieved compared with those obtained throughBorn-Markov approximation. The phonon-induced decoherence is analyzed in detailafter a derivation of phonon spectral density. It is shown that due to the inhibition ofthe electron-phonon coupling in the confined structure of the slab, the quality factor ofthe charge qubit in cavity is two orders of magnitude higher than that in the bulk case.Furthermore, a robust qubit can be obtained.In addition, we also do some research work about the dynamics of a coherentlydriven localized exciton in a semiconducting single-wall carbon nanotube, and com-pare the results obtained through our method and Born-Markov approximation. Ob-vious disparity is shown in the comparison. It demonstrates that our method exhibitsmore advantages when dealing with models such as semiconducting single-wall car-bon nanotube (SWNT) because the exciton-phonon coupling of SWNT is relativelylarge and our method is more suitable in this case.In addition, we investigate the related properties of the SWNT double quantumdot qubit embedded in a phonon cavity. At the end of the thesis, we also derive and dis-cuss the coherent oscillation population effect in semiconductor quantum dot. Hope-fully, our work can be instructive and helpful for the related research such as the qubit manipulations, the decoherence mechanisms in quantum dot systems and the design,fabrication and application of novel nano-devices in the future.