Coherent long-distance displacement of individual electron spins

TL;DR

This paper demonstrates the coherent displacement of individual electron spins over 5 micrometers in a quantum dot system, significantly extending spin coherence length and enabling long-range quantum information transfer.

Contribution

It introduces a method for coherently moving electron spins over long distances in quantum dots, preserving coherence and enhancing quantum control capabilities.

Findings

Electron spins displaced coherently over 5 micrometers

Spin coherence length is 8 times longer than without displacement

Displacement achieved at speeds approaching 100 m/s

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 important experimental efforts to control the electron displacement over long distances, keeping the electron spin coherence after transfer remained up to now elusive. Here we demonstrate that individual electron spins can be displaced coherently over a distance of 5 micrometers. This displacement is realized on a closed path made of three tunnel-coupled lateral quantum dots. Using fast quantum dot control, the electrons tunnel from one dot to another at a speed approaching 100 m/s. We find that the spin coherence length is 8 times longer than expected from the electron spin coherence without displacement. Such an enhanced spin coherence points at a process similar to motional narrowing observed in nuclear magnetic resonance experiments6. The demonstrated coherent displacement will enable long-range interaction between distant spin-qubits and will open the route towards non-abelian and holonomic manipulation of a single electron spin.