Reducing quantum control for spin-spin entanglement distribution

TL;DR

This paper introduces a robust protocol for generating stationary entanglement between remote spins via scattering of mediators, effective even with classical mediators and without complex control or feedback, applicable across various physical systems.

Contribution

The authors propose a novel entanglement distribution scheme that does not require mediator initialization, post-selection, or feedback, and works efficiently with classical mediators.

Findings

Protocol generates two-qubit singlet states without mediator initialization.

Scheme is resilient to non-optimal coupling and dephasing effects.

Classical mediators can enhance efficiency over quantum mediators.

Abstract

We present a protocol that sets maximum stationary entanglement between remote spins through scattering of mobile mediators without initialization, post-selection or feedback of the mediators' state. No time-resolved tuning is needed and, counterintuitively, the protocol generates two-qubit singlet states even when classical mediators are used. The mechanism responsible for such effect is resilient against non-optimal coupling strengths and dephasing affecting the spins. The scheme uses itinerant particles and scattering centres and can be implemented in various settings. When quantum dots and photons are used a striking result is found: injection of classical mediators, rather than quantum ones, improves the scheme efficiency.