Coherent long-distance displacement of individual electron spins

H Flentje,A D Wieck,T Meunier,P.-A Mortemousque,R Thalineau,C Bäuerle,A Ludwig

doi:10.1038/s41467-017-00534-3

Abstract

Controlling nanocircuits at the single electron spin level is a possible route for large-scale quantum information processing. In this context, individual electron spins have been identified as versatile quantum information carriers to interconnect different nodes of a spin-based semiconductor quantum circuit. Despite extensive experimental efforts to control the electron displacement over long distances, maintaining electron spin coherence after transfer remained elusive up to now. Here we demonstrate that individual electron spins can be displaced coherently over a distance of 5 µm. This displacement is realized on a closed path made of three tunnel-coupled lateral quantum dots at a speed approaching 100 ms−1. We find that the spin coherence length is eight times longer than expected from the electron spin coherence without displacement, pointing at a process similar to motional narrowing observed in nuclear magnetic resonance experiments. The demonstrated coherent displacement will open the route towards long-range interaction between distant spin qubits.

Highlights

Controlling nanocircuits at the single electron spin level is a possible route for large-scale quantum information processing
While it is clear that the spin degree of freedom of an electron is an interesting building block for processing and storing quantum information[1–6], important questions concerning the system scalability remain to be addressed before building a large-scale spin-based quantum processor
The problem reduces to the ability to transfer quantum information on a chip

Summary

Introduction

Controlling nanocircuits at the single electron spin level is a possible route for large-scale quantum information processing. In this context, individual electron spins have been identified as versatile quantum information carriers to interconnect different nodes of a spin-based semiconductor quantum circuit. We demonstrate that individual electron spins can be displaced coherently over a distance of 5 μm This displacement is realized on a closed path made of three tunnel-coupled lateral quantum dots at a speed approaching 100 ms−1. Even though electron and spin transfer have been demonstrated, the technology of moving quantum dots at the single electron level is not yet controlled well enough to investigate coherence properties[12]. Displacement-induced spin-flip processes are revealed with the dependence of the coherence time with the externally applied magnetic field and limit the distance over which electron spin coherence can be preserved

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Results

Conclusion