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Motivation:
- Single-shot spin readout is an essential part in solid-state quantum computing, which relies on quantum tunneling process.
- Spin readout fidelity depends on the tunneling time that needs to be optimized.
- A comprehensive quantitative theory that can provide design guidance for spin readout devices using a quantum mechanical description is lacking
Approach:
- Multi-scale modeling approach to simulate in-plane spin readout devices.
- Semi-classical approach for the electrostatic solution of the SET island in the framework of Sentaurus TCAD tool
- Large-scale atomistic tight-binding and self-consistent field approach for the donor and the SET wavefunction
- Bardeen’s transfer matrix method for the tunneling time calculation.
Results/Impact:
- Proposed a comprehensive theory based on atomistic modeling for tunneling time calculation in spin readout devices.
- The tunneling time between the qubit and the SET island can vary by 5-6 orders of magnitude with their separation changing by ~10 nm.
- Tunneling time decreases with the donor number increase, and is relatively insensitive to the cluster configuration. It decreases significantly with the bound electron number.
- Tunneling to an excited state of the SET island is roughly similar to that to the ground state, which is followed by a phonon-induced relaxation process. Relative to the tunneling time, the relaxation is longer from a valley state and much shorter from an orbital state
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