Simulating coherent electron shuttling in quantum dots

Coherent transport of electron spins is required for several proposed large-scale architectures based on quantum dot spin qubits [1,2]. In [1], spin singlets are distributed across neighboring computational nodes by sequential single-electron tunneling through a linear array of quantum dots. We adopt a simplified metal-gate geometry for silicon MOS dots and use the Nextnano software to determine the potential landscape as a function of varying gate voltages, subsequently solving the time-dependent Schrodinger equation in 1D to simulate coherent shuttling. An algorithm is presented that calculates time-dependent voltages that maintain a desired fidelity with the ground state orbital wavefunction. These tools are used to vary the geometrical device parameters to maximize the electron shuttling velocity. We further show that the essential physics can be captured in an effective Hamiltonian model, which allows us to explore how spin-orbit and valley states affect the shuttling fidelity and maximum velocity.

[1] B. Buonacorsi, et al., arXiv:1807.09941 (2018)
[2] R. Li, et al., Science advances 4(7), eaar3960 (2018)