Directionality and quantum backfire in continuous-time quantum walks from delocalized states: Exact results
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| author | Ximenes, Jefferson J. Pires, Marcelo A. Villas-Bôas, José M. |
| author_facet | Ximenes, Jefferson J. Pires, Marcelo A. Villas-Bôas, José M. |
| contents | 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_01584 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Directionality and quantum backfire in continuous-time quantum walks from delocalized states: Exact results Ximenes, Jefferson J. Pires, Marcelo A. Villas-Bôas, José M. Quantum Physics Mathematical Physics 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. |
| title | Directionality and quantum backfire in continuous-time quantum walks from delocalized states: Exact results |
| topic | Quantum Physics Mathematical Physics |
| url | https://arxiv.org/abs/2510.01584 |