Quantum advantage in transfer of quantum states

TL;DR

This paper demonstrates a clear quantum advantage in the time-optimal transfer of excitations in a lattice, showing quantum systems outperform classical counterparts in speed due to superposition of trajectories.

Contribution

It identifies a specific scenario where quantum advantage is well-defined and rigorously proven, involving multi-trajectory propagation in a lattice with various couplings.

Findings

Quantum transfer is faster than any single classical trajectory.

Superposition of multiple paths accelerates excitation transfer.

The advantage is rigorously proven for a specific lattice model.

Abstract

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.