Directionality and quantum backfire in continuous-time quantum walks from delocalized states: Exact results

• URL: http://arxiv.org/abs/2510.01584v1
• Date: Thu, 02 Oct 2025 02:05:07 GMT
• Title: Directionality and quantum backfire in continuous-time quantum walks from delocalized states: Exact results
• Authors: Jefferson J. Ximenes, Marcelo A. Pires, José M. Villas-Bôas,
• Abstract summary: We derive analytical results for continuous-time quantum walks from a new class of initial states with tunable delocalization.<n>We provide closed-form equations for key observables, revealing three notable findings.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We derive analytical results for continuous-time quantum walks from a new class of initial states with tunable delocalization. The dynamics are governed by a Hamiltonian with complex hopping amplitudes. We provide closed-form equations for key observables, revealing three notable findings: (1) the emergence of directed quantum transport from completely unbiased initial conditions; (2) a quantum backfire effect, where greater initial delocalization enhances short-time spreading but counterintuitively induces a comparatively smaller long-time spreading after a crossing time $t_{\mathrm{cross}}$; and (3) an exact characterization of survival probability, showing that the transition to an enhanced $t^{-3}$ decay is a fine-tuned effect. Our work establishes a comprehensive framework for controlling quantum transport through the interplay between intermediate initial delocalization and Hamiltonian phase.

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