Controlling Synthetic Spin-Orbit Coupling in a Silicon Quantum Dot using Magnetic Field Direction

Xin Zhang, Yuan Zhou, Rui-Zi Hu, Rong-Long Ma, Ming Ni, Ke Wang, Gang Luo, Gang Cao, Gui-Lei Wang, Peihao Huang, Xuedong Hu, Hong-Wen Jiang, Hai-Ou Li, Guang-Can Guo, Guo-Ping Guo

Published 2020-12-29Version 1

Tunable synthetic spin-orbit coupling (s-SOC) is one of the key challenges in various quantum systems, such as ultracold atomic gases, topological superconductors, and semiconductor quantum dots. Here we experimentally demonstrate controlling the s-SOC by investigating the anisotropy of spin-valley resonance in a silicon quantum dot. As we rotate the applied magnetic field in-plane, we find a striking nonsinusoidal behavior of resonance amplitude that distinguishes s-SOC from the intrinsic spin-orbit coupling (i-SOC), and associate this behavior with the previously overlooked in-plane transverse magnetic field gradient. Moreover, by theoretically analyzing the experimentally measured s-SOC field, we predict the quality factor of the spin qubit could be optimized if the orientation of the in-plane magnetic field is rotated away from the traditional working point.