Complete switching of transverse and longitudinal spin-photon coupling in silicon

Abstract

Silicon spin qubits have emerged as one of the most promising platforms for quantum computing. To achieve scalability, the spin-photon coupling in the frame of circuit-QED offers a reliable architecture that garners significant attention. Depending on the coupling mechanisms, spin-photon coupling is categorized into transverse (g_x) and longitudinal (g_z) components, each offering distinct advantages for operation and readout, respectively. In practical scenarios, g_x and g_z often coexist and interfere with each other. To enable on-demand separation of these two couplings, we propose an alternative scheme based on spin-orbit torque (SOT). By employing SOT to switch the magnetization of micromagnets, the symmetry of the stray fields surrounding the spin qubit is modified, naturally isolating g_x and g_z. Furthermore, within this SOT scheme, we demonstrate that the dynamic longitudinal coupling (g ^dy_z ) can also be fully decoupled from g_x through applying appropriate parametric driving. Our results thus pave the way toward scalable silicon spin qubit architectures.