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arXiv · 2512.08141

The strength of weak coupling

Alastair Kay·Christino Tamon
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Abstract

A paradoxical idea in quantum transport is that attaching weakly-coupled edges to a large base graph creates high-fidelity quantum state transfer. We provide a mathematical treatment that rigorously prove this folklore idea. Our proofs are elementary and build upon the Feshbach-Schur method from perturbation theory. We also show the idea is effective in circumventing Anderson localization in spin chains and finding speedups in hitting times useful for quantum search.

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Alastair Kay, Christino Tamon. 2025-12-09. The strength of weak coupling. https://arxiv.org/abs/2512.08141

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