Hanson R, Witkamp B, Vandersypen L M K, van Beveren L H Willems, Elzerman J M, Kouwenhoven L P
Department of NanoScience and ERATO Mesoscopic Correlation Project, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands.
Phys Rev Lett. 2003 Nov 7;91(19):196802. doi: 10.1103/PhysRevLett.91.196802.
We have measured the relaxation time, T1, of the spin of a single electron confined in a semiconductor quantum dot (a proposed quantum bit). In a magnetic field, applied parallel to the two-dimensional electron gas in which the quantum dot is defined, Zeeman splitting of the orbital states is directly observed by measurements of electron transport through the dot. By applying short voltage pulses, we can populate the excited spin state with one electron and monitor relaxation of the spin. We find a lower bound on T1 of 50 micros at 7.5 T, only limited by our signal-to-noise ratio. A continuous measurement of the charge on the dot has no observable effect on the spin relaxation.
我们测量了限制在半导体量子点（一种被提议作为量子比特的结构）中的单个电子自旋的弛豫时间T1。在与定义量子点的二维电子气平行施加的磁场中，通过测量电子穿过量子点的输运，直接观测到了轨道态的塞曼分裂。通过施加短电压脉冲，我们能用一个电子填充激发的自旋态，并监测自旋的弛豫。我们发现在7.5特斯拉时T1的下限为50微秒，这仅受我们的信噪比限制。对量子点上电荷的连续测量对自旋弛豫没有可观测的影响。
