Fullerene Molecules Antiferromagnetic Quantum Computing Structure

Due to the special structure of C60, it has been widely studied since its discovery in the 1980s. Subsequently, a new direction fullerene, which includes endohedral and doped fullerenes, and its ramification carbon nanotube etc, is developed,. Now fullerene is applied to medical science, chemistry, as well as solid-state physics. For example, fullerene has been utilized as superconducting material, optical switch of three-dimensions, lubricating material etc.Traditionally, anti-ferromagnetic properties of fullerenes and their ramifications are not systematically studied in physics. Both the experimental and theoretical works show that there exists the anti-ferromagnetism for C60, and the ground state energy is given. In this research, we have studied the magnetism of C82 by using the Heisenberg model for spin sub-system. According to the symmetrical structure of the molecule C82 and the mode of the bond of the three nearest atoms of each atom ,we develop a matrix of 82*82. Using the formulated 82*82 matrix, we calculate the eigenvalue. The minimal eigenvalue of the matrix is corresponding to the ground state energy of the sub-spin system of C82 fullerene moleculeand the minimal energy is E=82 2 2 ( 2 =-2.794).In this thesis, we also try to explore how to overcome the decoherence in quantum computer. Decoherence has been a leading research area in quantum computing, because the critical interaction of quantum system with the corresponding environment, such as, electron spin relaxation in semiconductor QD via interaction with nuclear spins. Furthermore, the master equation with Markovian approximation is used to investigate the electron spin relaxation process for the system A@Ceo at low temperature. Our calculation shows that at very low temperature, the process of the electron spin interaction with the nuclear spin is reasonable to use Markovian approximation. At lower magnetic field the polarization decayis observed in exponential form, and transverse decay time is 2 times longitudinal one. For a kind of A@C60 (A=14N,15N,31P) endohedral fullerenes, the decay time is around 10-100ns. The decay time is of the order of h/ A , which is similar to the other results. For astrong external magnetic field, i.e. B A/2g B , longitudinal polarization strongly depends on the external magnetic field, and the decay time is suppressed.