Johnson A C, Petta J R, Taylor J M, Yacoby A, Lukin M D, Marcus C M, Hanson M P, Gossard A C
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Nature. 2005 Jun 16;435(7044):925-8. doi: 10.1038/nature03815. Epub 2005 Jun 8.
The spin of a confined electron, when oriented originally in some direction, will lose memory of that orientation after some time. Physical mechanisms leading to this relaxation of spin memory typically involve either coupling of the electron spin to its orbital motion or to nuclear spins. Relaxation of confined electron spin has been previously measured only for Zeeman or exchange split spin states, where spin-orbit effects dominate relaxation; spin flips due to nuclei have been observed in optical spectroscopy studies. Using an isolated GaAs double quantum dot defined by electrostatic gates and direct time domain measurements, we investigate in detail spin relaxation for arbitrary splitting of spin states. Here we show that electron spin flips are dominated by nuclear interactions and are slowed by several orders of magnitude when a magnetic field of a few millitesla is applied. These results have significant implications for spin-based information processing.
被限制的电子的自旋，当其最初沿某个方向取向时，在一段时间后会失去该取向的记忆。导致自旋记忆这种弛豫的物理机制通常涉及电子自旋与其轨道运动或核自旋的耦合。之前仅针对塞曼或交换分裂自旋态测量了被限制电子自旋的弛豫，其中自旋 - 轨道效应主导弛豫；在光谱学研究中已观察到由于原子核导致的自旋翻转。利用由静电门定义的孤立砷化镓双量子点和直接时域测量，我们详细研究了自旋态任意分裂情况下的自旋弛豫。在此我们表明，电子自旋翻转主要由核相互作用主导，并且当施加几毫特斯拉的磁场时，自旋翻转会减慢几个数量级。这些结果对基于自旋的信息处理具有重要意义。
