The Decoupling Pulse Sequences And The Simulation Of Solid State Nuclear Magnetic Resonance

Quantum information is an interdisciplinary field based on quantum me-chanics and information science. Quantum computer is a information processor based on quantum mechanics, which is totally different from the principle of tra-ditional computer, with the advantages of many traditional computer did not have, such as processing speed, and capacity for processing information and so on. Now there are dozens of implementation scheme being proposed, in which the Nuclear Magnetic Resonance (NMR) quantum computing has the most research results in quantum computing experiment and theoretical research, has become a promising platform to realize quantum computer. Quantum computing has made significant achievement in liquid NMR due to its simple Hamiltonian form, such as the realization of the basic quantum logic gate, and so on. There are based on the motion of molecules in liquid, leading the good nature of coherence which provides a good test platform for a right quantum computing and the quantum algorithm. But the liquid NMR quantum computing has limitations, such as the nono-scalability of pseudo-pure state preparation; the large ratio of the gate time over the de-coherence time; the difficulty of resetting qubits and so on. And in solid-state NMR system, the system can be highly polarized increasing the sen-sitivity necessary to read out the results of computations; the de-coherence rates can be made slower; coupling between spins is dipolar coupling which is higher, permitting faster operations; there are mechanisms which can be used for dy-namically resetting qubits, thus making it possible to remove information from a system and to implement error-correction efficiently. The biggest disadvantage of solid state NMR is the molecules in solid can’t rotating or moving as in liquid, leading the anisotropic interaction being reserved, leading the main obstacle of quantum computation in solid-state NMR is the influence of the de-coherence. So improving the coherent time is the first condition of quantum computing. We can use the decoupling technology of solid state NMR, such as MAS, Multiple pulse, or combination of both MAS and multiple pulse called CRAMPS to average out various anisotropic interaction, to improve the coherence of solid-state NMR sys-tem, it take a big step to do quantum computing in solid state NMR. This paper firstly introduced the background and theory of quantum computing, the basic knowledge of NMR quantum computing, familiar with the principle of computer simulation of solid nuclear magnetic and SIMPSON, a strong solid nuclear mag-netic simulation software; And then studied the principle of different decoupling method in solid, the advantages and disadvantages of different decoupling method under different circumstances, and the different applicable conditions; further to simple research of recoupling sequence. Based on these, the different sequences are compared, and the computer simulation of a series of results are obtained, such as in heteronuclear decoupling, TPPM decoupling is better than CW de-coupling; in homonuclear decoupling, high MAS speed for SAM decoupling; the LG decoupling sequence is better in static state, and so on. Finally, combining with the technologies of the decoupling and recoupling, applying to the construc-tion of quantum gates on crystal system realized two qubits quantum gate, and MATLAB simulation and SIMPSON simulation which is closer to the experiment verified the theory above.