A bipartite spin system is proposed for which a fast transfer from one defined state into another exists. For sufficient coupling between the spins, this implements a bit-flipping mechanism which is much faster than that induced by tunneling. The states correspond in the semiclassical limit to equilibrium points with a stability transition from elliptic-elliptic stability to complex instability for increased coupling. The fast transfer is due to the spiraling characteristics of the complex unstable dynamics. Based on the classical system we find a universal scaling for the transfer time, which even applies in the deep quantum regime. By investigating a simple model system, we show that the classical stability transition is reflected in a fundamental change of the structure of the eigenfunctions.
@article{arxiv.2303.16171,
title = {Fast Bit-Flipping based on a Stability Transition of Coupled Spins},
author = {Maximilian F. I. Kieler and Arnd Bäcker},
journal= {arXiv preprint arXiv:2303.16171},
year = {2023}
}