Suppressing Si Valley Excitation and Valley-Induced Spin Dephasing for Long-Distance Shuttling

Area of Science:

• Quantum Computing
• Condensed Matter Physics
• Materials Science

Background:

• Electron spin shuttling in silicon quantum dots is crucial for quantum computing.
• Errors during shuttling can arise from spin and valley degree of freedom entanglement.
• Scalable and high-fidelity transport is a key challenge in silicon-based quantum devices.

Purpose of the Study:

• To present a scalable protocol for suppressing errors during electron spin shuttling.
• To enable fast and high-fidelity quantum transport in silicon quantum dots.
• To ensure spin and valley degrees of freedom remain unentangled during shuttling.

Main Methods:

• Mapping the valley Hamiltonian to a Landau-Zener problem to model nonadiabatic dynamics.
• Optimizing the shuttling velocity profile over small path segments.
• Utilizing a virtual z rotation to compensate for spin phase accumulation.

Main Results:

• The protocol ensures reliable return of the valley state to the ground state.
• Spin phase accumulation becomes predictable and is compensated efficiently.
• Error suppression is minimal in time cost and complexity, independent of shuttle distance.
• Achieved maximum velocities are orders of magnitude higher than current experimental speeds.

Conclusions:

• The presented protocol offers a chip-scale solution for high-fidelity quantum transport.
• This method significantly advances silicon spin-based quantum computing.
• The approach minimizes errors and enhances the reliability of quantum operations.