Kavli Institute of Nanoscience, TU Delft, 2600 GA Delft, The Netherlands.
Nat Commun. 2011 Nov 22;2:556. doi: 10.1038/ncomms1561.
Artificial molecules containing just one or two electrons provide a powerful platform for studies of orbital and spin quantum dynamics in nanoscale devices. A well-known example of these dynamics is tunnelling of electrons between two coupled quantum dots triggered by microwave irradiation. So far, these tunnelling processes have been treated as electric-dipole-allowed spin-conserving events. Here we report that microwaves can also excite tunnelling transitions between states with different spin. We show that the dominant mechanism responsible for violation of spin conservation is the spin-orbit interaction. These transitions make it possible to perform detailed microwave spectroscopy of the molecular spin states of an artificial hydrogen molecule and open up the possibility of realizing full quantum control of a two-spin system through microwave excitation.
仅包含一个或两个电子的人工分子为在纳米尺度设备中研究轨道和自旋量子动力学提供了一个强大的平台。这些动力学的一个著名例子是微波辐照引发的两个耦合量子点之间的电子隧穿。到目前为止，这些隧穿过程一直被视为电偶极子允许的自旋守恒事件。在这里，我们报告说，微波也可以激发不同自旋态之间的隧穿跃迁。我们表明，违反自旋守恒的主要机制是自旋轨道相互作用。这些跃迁使得对人工氢分子的分子自旋态进行详细的微波光谱学研究成为可能，并为通过微波激发实现双自旋系统的完全量子控制开辟了可能性。
