A. Stepanenko

K. Chernova

M. Gorlach

Simultaneous propagation along multiple paths speeds excitation transfer in long-range lattices, proving an evident quantum advantage.

A decisive advantage of quantum over classical systems is widely sought but hard to prove unambiguously. Considering time-optimal excitation transfer in lattices with nearest-neighbor and long-range couplings, we show that the quantum superposition of trajectories strictly reduces transfer time. The result is a rigorous demonstration of quantum superiority, with an explicit, provable margin over classical strategies.

Quantum advantage, broadly understood as the ability of quantum systems to significantly outperform their classical counterparts, underpins current interest to quantum technologies and is a topic of active investigation. In many situations, its existence is subject to debate, and the areas of supremacy of large-scale quantum systems are not well defined. Here, we uncover a novel niche where quantum advantage can be clearly defined and proven. We study a time-optimal transfer of excitations in the lattice involving both nearest-neighbor and longer-range couplings. We prove that the quantum-mechanical property of a particle to propagate along several trajectories simultaneously speeds up the transfer process, which takes a shorter time compared to any particular trajectory and thus provides a clear example of quantum advantage.

Multi-path transfer

Quantum advantage in transfer of quantum states