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arXiv · 1909.03933

Landau-Zener Formula in a "Non-Adiabatic" regime for avoided crossings

Takuya Watanabe·Maher Zerzeri
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Abstract

We study a two-level transition probability for a finite number of avoided crossings with a small interaction. Landau-Zener formula, which gives the transition probability for one avoided crossing as $e^{-\pi\frac{\varepsilon^{2}}{h}}$, implies that the parameter $h$ and the interaction $\varepsilon$ play an opposite role when both tend to $0$. The exact WKB method produces a generalization of that formula under the optimal regime $\frac{h}{\varepsilon^2}$ tends to~0. In this paper, we investigate the case $\frac{\varepsilon^2}{h}$ tends to 0, called "non-adiabatic" regime. This is done by reducing the associated Hamiltonian to a microlocal branching model which gives us the asymptotic expansions of the local transfer matrices.

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Takuya Watanabe, Maher Zerzeri. 2019-09-09. Landau-Zener Formula in a "Non-Adiabatic" regime for avoided crossings. https://arxiv.org/abs/1909.03933

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