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arxiv: 2604.05915 · v1 · submitted 2026-04-07 · 🪐 quant-ph · cond-mat.mes-hall· physics.optics

Quantum advantage in transfer of quantum states

Andrei Stepanenko , Kseniia Chernova , Maxim Gorlach This is my paper

Pith reviewed 2026-05-10 20:10 UTC · model grok-4.3

classification 🪐 quant-ph cond-mat.mes-hallphysics.optics
keywords quantum advantagestate transferquantum latticemulti-path propagationexcitation transferquantum superpositionquantum speedup
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The pith

Quantum particles transfer excitations faster by exploring multiple trajectories simultaneously than any single classical path allows.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper establishes that in a lattice with nearest-neighbor and longer-range couplings, a quantum particle can move an excitation from one site to another in less time than required by any individual trajectory. This occurs because the particle propagates along several paths at once through superposition and interference. A sympathetic reader would care since the result supplies a concrete, provable case of quantum advantage in a basic transport setting without needing large-scale entanglement or complex algorithms. The authors focus on time-optimal transfer and show that the quantum minimum time is set by the collective effect of paths rather than the properties of any one route.

Core claim

In the time-optimal transfer of excitations in the lattice involving both nearest-neighbor and longer-range couplings, 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.

What carries the argument

Multi-trajectory quantum propagation via superposition, which lets the excitation reach the target via effective interference across paths instead of being limited to one fixed route.

If this is right

  • The minimal achievable transfer time is strictly shorter than the duration of the fastest individual path.
  • The advantage remains even when longer-range couplings are included in the lattice Hamiltonian.
  • Any classical process restricted to a single trajectory cannot reach the quantum speed.
  • The speedup defines a specific, verifiable niche for quantum advantage in excitation transport.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • This multi-path mechanism could guide designs for faster quantum routing in lattice-based communication networks.
  • Small-scale experiments in trapped-ion or photonic systems could directly measure the predicted time reduction.
  • The result may link to broader questions about quantum speed limits and information propagation in many-body systems.

Load-bearing premise

Classical transfer must follow exactly one fixed trajectory at a time without using any parallel exploration or optimization over multiple routes.

What would settle it

An explicit calculation or numerical simulation in the same lattice model showing that the fastest single classical trajectory achieves a transfer time equal to or shorter than the quantum time would disprove the advantage.

Figures

Figures reproduced from arXiv: 2604.05915 by Andrei Stepanenko, Kseniia Chernova, Maxim Gorlach.

Figure 1
Figure 1. Figure 1: FIG. 1 [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3 [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
read the original 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.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 0 minor

Summary. The manuscript studies time-optimal transfer of excitations on a lattice with both nearest-neighbor and longer-range couplings. It claims to prove that the quantum property of simultaneous propagation along multiple trajectories yields a strictly shorter transfer time than along any single classical trajectory, thereby establishing a clear quantum advantage.

Significance. If the central claim is rigorously established with a properly justified classical baseline, the result would supply a simple, falsifiable example of quantum advantage in a basic state-transfer task. This could clarify the boundaries of quantum superiority in lattice dynamics without requiring large-scale entanglement or error correction.

major comments (1)
  1. [Abstract] Abstract: the claim that quantum transfer is faster than 'any particular trajectory' is load-bearing, yet the manuscript does not derive why a classical model is restricted to a single fixed trajectory. A classical agent could instead select the single fastest available hop (permitted by the longer-range couplings) or optimize over an ensemble of paths, potentially achieving comparable or shorter times without superposition. No section demonstrates that such classical strategies are disallowed or slower.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their careful reading of the manuscript and for identifying an important point of clarification regarding the classical baseline. We address this comment below and will revise the manuscript accordingly to strengthen the presentation.

read point-by-point responses

  1. Referee: [Abstract] Abstract: the claim that quantum transfer is faster than 'any particular trajectory' is load-bearing, yet the manuscript does not derive why a classical model is restricted to a single fixed trajectory. A classical agent could instead select the single fastest available hop (permitted by the longer-range couplings) or optimize over an ensemble of paths, potentially achieving comparable or shorter times without superposition. No section demonstrates that such classical strategies are disallowed or slower.

    Authors: We thank the referee for highlighting the need to make the classical baseline explicit. In our model, a classical trajectory corresponds to a deterministic, single path followed by the excitation, as a classical particle lacks the ability to propagate in superposition. The time associated with any such trajectory is the propagation time along the sequence of couplings defining that path. Our central result derives a strict upper bound on the minimal quantum transfer time that is shorter than the time required along any individual classical trajectory. This includes the trajectory that employs the single fastest (longest-range) hop, as well as any other single path. The speedup arises because the quantum state evolves coherently along multiple paths simultaneously, with interference enabling the target site to be reached in less time than the shortest single-path classical time. A classical agent choosing the fastest hop is simply selecting one particular trajectory (the minimal-time one), which our bound already shows is outperformed by the quantum dynamics. An ensemble of paths in the classical setting reduces to a probabilistic choice among single trajectories; the effective transfer time remains bounded below by the shortest individual trajectory time and cannot benefit from coherent superposition. We will add a dedicated subsection defining the classical model, contrasting it with the quantum case, and explicitly comparing against the strategies mentioned (fastest-hop selection and path ensembles). We will also refine the abstract to emphasize that the quantum time is strictly less than the minimum over all single classical trajectories. revision: yes

Circularity Check

0 steps flagged

No circularity detected; proof is self-contained

full rationale

The paper claims to prove quantum advantage via simultaneous propagation over multiple trajectories yielding shorter transfer time than any single classical trajectory. No equations, fitted parameters, self-citations, or ansatzes appear in the abstract or provided text that reduce the central claim to a definition or input by construction. The classical comparison is explicitly scoped to single fixed trajectories as a modeling premise, not derived from the quantum result itself. This constitutes a standard external benchmark rather than a self-referential loop, leaving the derivation independent and non-circular.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review yields no explicit free parameters, axioms, or invented entities; standard quantum mechanics is presupposed but not detailed.

pith-pipeline@v0.9.0 · 5416 in / 927 out tokens · 37069 ms · 2026-05-10T20:10:47.179216+00:00 · methodology

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Reference graph

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