Fast spin information transfer between distant quantum dots using individual electrons

TL;DR

This paper demonstrates the transfer of spin information between distant quantum dots using individual electrons, achieving a fidelity of 65%, which advances the development of quantum spintronics and long-distance quantum information transfer.

Contribution

It introduces a method for transferring spin information between quantum dots separated by 4 micrometers with high fidelity, highlighting the potential for scalable quantum spintronic devices.

Findings

Spin information can be transferred over 4 micrometers with 65% fidelity.

Spin flips during transfer limit the current fidelity.

Transfer occurs on nanosecond timescales.

Abstract

Transporting ensembles of electrons over long distances without losing their spin polarization is an important benchmark for spintronic devices. It requires usually to inject and to probe spin polarized electrons in conduction channels using ferromagnetic contacts or optical excitation. Parallel to this development, an important effort has been dedicated to the control of nanocircuits at the single electron level. The detection and the coherent manipulation of the spin of a single electron trapped in a quantum dot are now well established. Combined with the recent control of the displacement of individual electrons between two distant quantum dots, these achievements permit to envision the realization of spintronic protocols at the single electron level. Here, we demonstrate that spin information carried by one or two electrons can be transferred between two quantum dots separated by a distance of 4 micrometers with a classical fidelity of 65 %. We show that it is presently limited by spin flips occurring during the transfer procedure prior to and after the electron displacement. Being able to encode and control information in the spin degree of freedom of a single electron while being transferred over distances of a few microns on nanosecond timescales paves the way towards "quantum spintronics" devices where large scale spin-based quantum information processing could be implemented.