Research On New Quantum Computation Mode And Physical Realization System

The ultimate goal of quantum computation research is to build a powerful quantum computer, which is a new type computer based on quantum mechanics. It has been proved in theory that a quantum computer can fully simulate the classical computer, and further it can solve specific problems efficiently which classical computer cannot. Quantum computation research has the multidisciplinary character that combines quantum physics, mathematics, material science, and engineering etc. It has become one of the most active areas in physical research, and attracted lots of the most brilliant brains in the world. However, it is still not clear today that the ultimate quantum computer would be built in which mode and in which physical system. Many possible ways are under research.In this thesis we summarize our researches on the new quantum computation mode and new physical realization system. We experimentally simulated the one-way quantum computation mode in nuclear magnetic resonance (NMR) system for the first time, utilizing the liquid-state NMR technologies. We deterministically prepared a four-particle graph state, and demonstrated the Deutsch-Josza algorithm on it in the one-way manner. The results of our experiment verified the feasibility of the one-way mode, and would be helpful to other physical systems for future scalable one-way quantum computation. For the new physical realization system, we concentrate on the endohedral fullerenes. We proposed a scheme to realize the universal quantum gates in endohedral fullerenes. It solved the problem which due to the electron spin 3/2 and its transition degeneracy. Our scheme is a fundamental contribution to the endohedral fullerene based quantum computation. Further, we suggested a new quantum computation proposal based on endohedral fullerenes, in which the electron spins are used as auxiliary. Utilizing these auxiliary spins, it has more convenience in qubit (the nuclear spin) addressing, initialization, quantum gates, and read out, than previous proposals. Besides, we also provided a spin state tomography technology for the endohedral fullerene ensemble, which is feasible for the current electron spin resonance spectrometer with ENDOR (electron-nuclear double resonance) part.We anticipate that the ultimate realization of quantum computer would rely on the integrated system with different computation modes and even different physical realization systems. Our work have shown this distinguish feature in a primary step. The two-qubit gates which we proposed to construct the universal quantum gates in endohedral fullerenes, is not only an essential part of the logic circuit mode, but also could be used to prepare the graph state onto the nuclear spins which is the unique resource of the one-way mode. We also integrated the logic circuit mode and the global control mode in our electron spin assisted endohedral fullerene quantum computation scheme, according to which we solved the addressing problem of the nuclear spins. This reduces largely the technical requirements.