Huang Zhen, Sadiek Gehad, Kais Sabre
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA.
J Chem Phys. 2006 Apr 14;124(14):144513. doi: 10.1063/1.2192778.
We study the time evolution of a single spin coupled by exchange interaction to an environment of interacting spin bath modeled by the XY Hamiltonian. By evaluating the spin correlator of the single spin, we observed that the decay rate of the spin oscillations strongly depends on the relative magnitude of the exchange coupling between the single spin and its nearest neighbor J(') and coupling among the spins in the environment J. The decoherence time varies significantly based on the relative coupling magnitudes of J and J('). The decay rate law has a Gaussian profile when the two exchange couplings are of the same order J(') approximately J but converts to exponential and then a power law as we move to the regimes of J(')>J and J(')<J. We also show that the spin oscillations propagate from the single spin to the environmental spins with a certain speed. The effect of varying the anisotropic parameter, external magnetic field, and temperature on the decaying rate of the spin state is also discussed.
我们研究了一个通过交换相互作用与由XY哈密顿量建模的相互作用自旋浴环境耦合的单自旋的时间演化。通过评估单自旋的自旋关联函数，我们观察到自旋振荡的衰减率强烈依赖于单自旋与其最近邻之间的交换耦合J(')以及环境中自旋之间的耦合J的相对大小。退相干时间根据J和J(')的相对耦合大小而显著变化。当两个交换耦合具有相同量级J(')≈J时，衰减率定律具有高斯分布，但当我们进入J(')>J和J(')<J的区域时，它会转变为指数分布，然后是幂律分布。我们还表明，自旋振荡以一定速度从单自旋传播到环境自旋。此外，还讨论了改变各向异性参数、外部磁场和温度对自旋态衰减率的影响。
