Beijing Computational Science Research Center, Beijing 100084, China and Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China.
Phys Rev Lett. 2013 Aug 23;111(8):086805. doi: 10.1103/PhysRevLett.111.086805.
A semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC) can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external ac electric field, an effect called electric-dipole spin resonance. Here we develop a theory that can apply in the strong SOC regime. We find that there is an optimal SOC strength η(opt)=√2/2, where the Rabi frequency induced by the ac electric field becomes maximal. Also, we show that both the level spacing and the Rabi frequency of the spin-orbit qubit have periodic responses to the direction of the external static magnetic field. These responses can be used to determine the SOC in the nanowire.
具有强自旋轨道耦合（SOC）的半导体纳米线量子点可用于实现自旋轨道量子比特。与自旋量子比特相比，自旋轨道量子比特可以对外加交流电场做出响应，这种效应称为电偶极自旋共振。在这里，我们发展了一种适用于强 SOC 情形的理论。我们发现，存在一个最优的 SOC 强度 η（opt）=√2/2，此时由交流电场引起的拉比频率达到最大值。此外，我们还表明，自旋轨道量子比特的能级间隔和拉比频率都对外加静态磁场方向具有周期性响应。这些响应可用于确定纳米线中的 SOC。
