Abstract
In this paper, we investigate how to achieve high-fidelity electron spin transport in a GaAs double quantum dot. Our study examines fidelity loss in spin transport from multiple perspectives. We first study incoherent fidelity loss due to hyperfine and spin-orbit interaction. We calculate fidelity loss due to the random Overhauser field from hyperfine interaction, and spin relaxation rate due to spin-orbit interaction in a wide range of experimental parameters with a focus on the occurrence of spin hot spots. A safe parameter regime is identified in order to avoid these spin hot spots. We then analyze systematic errors due to non-adiabatic transitions in the Landau-Zener process of sweeping the interdot detuning, and propose a scheme to take advantage of possible Landau-Zener-Stückelberg interference to achieve high-fidelity spin transport at a higher speed. At last, we study another systematic error caused by the correction to the electron g-factor from the double dot potential, which can lead to a notable phase error. In all, our results should provide a useful guidance for future experiments on coherent electron spin transport.
Highlights
In universal quantum computing, quantum information inevitably needs to be transferred over finite distances on chip or between chips
Assuming the existence of a double quantum dot (DQD) potential, as illustrated in Fig. 1, changing the interdot detuning via an applied electric field shifts the ground orbital state from one dot to the other, thereby achieving electron transport
We investigated the spin transfer fidelity loss due to incoherent processes caused by the external environments, and found that they can be suppressed if certain conditions are met in the transport
Summary
Quantum information inevitably needs to be transferred over finite distances on chip or between chips. Other important quantum operations, such as error correction and spin readout, involve electron tunneling between quantum dots[30,33,34,35,36,37]. Quantum tunneling of an electron is usually driven by tuning the bias voltage between neighboring quantum dots During such a process, several factors could change the spin state of the electron and reduce the fidelity of spin transfer. The SOI together with the confinement potential causes corrections to the eigen-energies, leading to modification of the effective g-factor, which could be significant if a superposed spin state is being transferred. We study how to achieve high-fidelity spin and charge transfer through electron tunneling in a double dot. We point out that this correction can cause a significant error in the tracking of the phase difference between spin up and down states, and needs to be properly accounted for by mapping out the system parameters accurately during the detuning sweeping process
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