Abstract
We demonstrate a coherent spin shuttle through a GaAs/AlGaAs quadruple-quantum-dot array. Starting with two electrons in a spin-singlet state in the first dot, we shuttle one electron over to either the second, third, or fourth dot. We observe that the separated spin-singlet evolves periodically into the m = 0 spin-triplet and back before it dephases due to nuclear spin noise. We attribute the time evolution to differences in the local Zeeman splitting between the respective dots. With the help of numerical simulations, we analyze and discuss the visibility of the singlet-triplet oscillations and connect it to the requirements for coherent spin shuttling in terms of the inter-dot tunnel coupling strength and rise time of the pulses. The distribution of entangled spin pairs through tunnel coupled structures may be of great utility for connecting distant qubit registers on a chip.
Highlights
Single electron spins in semiconductor quantum dots have been proposed as a candidate qubit platform that may allow scalable quantum information processing.[1, 2]
Since ΔEzi;j is different for different pairs of dots, the frequency of the S-T0 oscillations is dependent on the location of the two electrons
The key requirement for a coherent spin shuttle in the presence of differences in Zeeman splitting between the dots in the array, is that the motion through the array be adiabatic with respect to the inter-dot tunnel couplings for the spin phase to be preserved
Summary
Single electron spins in semiconductor quantum dots have been proposed as a candidate qubit platform that may allow scalable quantum information processing.[1, 2] Recent progress in semiconductor quantum-dot structures have shown long single-spin coherence times and high-fidelity coherent operations.[3,4,5,6,7] linear arrays have been successfully scaled to triple and quadruple dots,[8,9,10,11,12] and 2 × 2 arrays have been demonstrated as well.[13] there are practical limitations to the size of tunnel-coupled quantum dot arrays in one or two dimensions. Coherent long-distance displacement of individual electron spins. arXiv:1701.01279)
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