| Quantum computation is one of the newest application fields of quantum mechanics. Although it was born no more than two decades, the investigation of its properties and functions has developed significantly. Its miraculous properties and powerful functions have been found gradually, which is becoming the impetus to put it forward. Nowadays, scientists are investigating intensively and extensively more theoretical topics of quantum computation and also devising a variety of types of practical setup for demonstrating experimentally as well. The technique of nuclear magnetic resonance (NMR) is one of most promising schemes for realizing quantum computing so far. Therefor, the experimental and theoretical investigation of the NMR quantum computing is chosen as the subject of the present dissertation, which includes a general treatment of preparation of pseudo-pure states, design of quantum logic gates and circuits and read out of the experimental results, as well as demonstrations of several important quantum algorithms and quantum information transmission. The major results of the thesis are as follows.· The pulse sequences for achieving some logic operations of cycles and transpositions of quantum states have been devised. Another quantum circuit of realizing the quantum Toffoli gate has also been proposed.· The density matrices of NMR quantum computing experiments have been successfully reconstructed by using the technique of state tomography and the quantum theories of NMR Fourier spectroscopy.· The scheme of preparing pseudo-pure state by logic labeling has been improved, which can reduce the 'garbage blocks', increase the effective blocks and thus enhance the signal-to-noise ratio. Meanwhile, the pseudo-pure state by the temporal labeling has been prepared experimentally.· The scheme of realizing Hogg's quantum search algorithm with NMR has been proposed and implemented with NMR in two-qubits system experimentally for the first time. The extracted data are in good agreement with the theory.· The pulse sequences for realizing quantum discrete Fourier transforms have been devised and successfully demonstrated in two-qubits system with NMR.· The quantum circuit of implementing quantum dense coding has been designed and experimentally realized with NMR. The experimental results are coincident with the original proposal. |
