Theory of Silicon Spin Qubit Relaxation in a Synthetic Spin-Orbit Field

Abstract

We develop the theory of single-electron silicon spin qubit relaxation in the presence of a magnetic field gradient. Such field gradients are routinely generated by on-chip micromagnets to allow for electrically controlled quantum gates on spin qubits. We build on a valley-dependent envelope function theory that enables the analysis of the electron wave function in a silicon quantum dot with an arbitrary roughness at the interface. We assume the presence of single-layer atomic steps at a Si/SiGe interface and study how the presence of a gradient field modifies the spin-mixing mechanisms. We show that our theoretical modeling can quantitatively reproduce results of experimental measurements of qubit relaxation in silicon in the presence of a micromagnet. We further study in detail how a field gradient can modify the EDSR Rabi frequency of a silicon spin qubit. While this strongly depends on the details of the interface roughness, interestingly, we find that adding a micromagnet on top of a spin qubit with an ideal interface can even reduce the EDSR frequency within some interval of the external magnetic field strength.

arXiv comment9 pages, 4 figures

References in corpus (26)

• Silicon Quantum Electronics
• A >99.9%-fidelity quantum-dot spin qubit with coherence limited by charge noise
• Computing with spin qubits at the surface code error threshold
• Fast universal quantum control above the fault-tolerance threshold in silicon
• Spin-flip transitions between Zeeman sublevels in semiconductor quantum dots
• Phonon-induced decay of the electron spin in quantum dots
• A Coherent Spin-Photon Interface in Silicon
• Two-qubit silicon quantum processor with operation fidelity exceeding 99%
• Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting
• Precision tomography of a three-qubit donor quantum processor in silicon
• Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells
• Theory of valley-orbit coupling in a Si/SiGe quantum dot
• Probing low noise at the MOS interface with a spin-orbit qubit
• Spin and valley-orbit splittings in SiGe/Si heterostructures
• Spin Splitting in Symmetrical SiGe Quantum Wells
• Large, tunable valley splitting and single-spin relaxation mechanisms in a Si/Si${}_x$Ge${}_{1-x}$ quantum dot
• Spin relaxation in a Si quantum dot due to spin-valley mixing
• Single-Spin Relaxation in a Synthetic Spin-Orbit Field
• Valley dependent anisotropic spin splitting in silicon quantum dots
• Interface induced spin-orbit interaction in silicon quantum dots and prospects for scalability
• Giant anisotropy of spin relaxation and spin-valley mixing in a silicon quantum dot
• Control of valley dynamics in silicon quantum dots in the presence of an interface step
• Electromagnetic control of valley splitting in ideal and disordered Si quantum dots
• Effects of Interface Steps on the Valley Orbit coupling in a Si/SiGe quantum dot
• Controlling Synthetic Spin-Orbit Coupling in a Silicon Quantum Dot with Magnetic Field
• Switching between relaxation hotspots and coldspots in disordered spin qubits