Long-Distance Entanglement of Soliton Spin Qubits in Gated Nanowires

TL;DR

This paper demonstrates how soliton-like charge states in gated nanowires can be used to achieve ultrafast entanglement and quantum gate operations between distant electron spin qubits, with exact quantum calculations.

Contribution

It introduces a method to realize ultrafast entangling gates between distant spin qubits using soliton-mediated transport in nanowires, with detailed quantum simulations.

Findings

Soliton-like charge states enable long-distance spin entanglement.

Ultrafast SWAP and $\

maximally entangled spin states can be generated over long distances.

Abstract

We investigate numerically charge, spin, and entanglement dynamics of two electrons confined in a gated semiconductor nanowire. The electrostatic coupling between electrons in the nanowire and the charges in the metal gates leads to a self-trapping of the electrons which results in soliton-like properties. We show that the interplay of an all-electrically controlled coherent transport of the electron solitons and of the exchange interaction can be used to realize ultrafast SWAP and entangling $\sqrt{\text{SWAP}}$ gates for distant spin qubits. We demonstrate that the latter gate can be used to generate a maximally entangled spin state of spatially separated electrons. The results are obtained by quantum mechanical time-dependent calculations with exact inclusion of electron-electron correlations.