Distinct Modes of Quantum Information Transfer in Power–Law Long-Range Spin Networks

We identify different regimes of quantum state transfer in long-range coupled spin-12 systems, where naturally occurring power–law interactions enable rapid, high-fidelity transfer with minimal engineering. Across a broad range of interaction profiles, from effectively nearest-neighbour coupling to Coulomb interactions, we show how long-range connectivity fundamentally reshapes the mechanisms underlying information propagation within such systems. For effectively short-range interactions, transfer follows familiar ballistic transfer dynamics: an initially localised excitation spreads across many eigenmodes concentrated within the approximately linear region of the spectrum, enabling robust wavepacket motion. In contrast, increasing long-distance interactions via lowering the power–law exponent α (α=1−2) drives a striking transformation, where the initial state becomes confined to progressively fewer eigenmodes, ultimately reducing the dynamics to the coherent participation of only a few states corresponding to the highest eigenenergies. This spectral localisation gives rise to emergent long-range oscillations between distant sites, revealing a distinct—and faster—transfer mechanism arising from the intrinsic structure of long-range quantum interactions rather than from full-system engineering pathways.