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arXiv 2406.14564cond-mat.dis-nncond-mat.mes-hallcond-mat.stat-mechphysics.optics
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一维局域化中的相位分布与单模波导中的相变

Phase distribution in 1D localization and phase transitions in single-mode waveguides

I. M. Suslov

AI总结:

本研究发现一维无序系统中组合相位ψ的分布随电子能量变化会发生相变,虽在电子系统中不可观测,但可通过单模光波导测量验证,同时推导了此前被忽略的相位χ的演化方程并分析其弛豫特性。

摘要:

一维无序系统中的电子局域化通常用随机相位近似来描述,此时传输矩阵中的相位φ和θ的分布被认为是均匀的。在一般情况下,随机相位近似不成立,当系统长度L增加时,演化方程包含三个独立变量,即朗道电阻ρ以及组合相位ψ=θ-φ和χ=θ+φ。相位χ不影响ρ的演化,因此在以往的论文中未被考虑。研究发现,当改变电子能量E时,相位ψ的分布在E_0点表现出一种不寻常的相变,其体现为ψ出现虚部。电阻分布P(ρ)在E_0点没有奇异性,因此这种相变在电子无序系统中看起来是不可观测的。然而,一维局域化理论可直接应用于单模光波导中的波传播。光学方法效率更高,并且提供了测量相位ψ和χ的可能性。一方面,这使得P(ψ)分布中的相变变得可观测,该相变可被视为一维系统中留存的迁移率边的“痕迹”。另一方面,相位χ的可观测性使得推导其演化方程具有实际意义,本文下文将给出该方程。当L趋于无穷大时,分布P(χ)向极限分布P_∞(χ)的弛豫由两个指数项描述,当能量E改变时,这两个指数项的指数函数存在二阶导数的跃变。

英文摘要:

Localization of electrons in 1D disordered systems is usually described in the random phase approximation, when distributions of phases φand θ, entering the transfer matrix, are considered as uniform. In the general case, the random phase approximation is violated, and the evolution equations (when the system length L is increased) contain three independent variables, i.e. the Landauer resistance ρand the combined phases ψ=θ-φand χ=θ+φ. The phase χdoes not affect the evolution of ρand was not considered in previous papers. The distribution of the phase ψis found to exhibit an unusual phase transition at the point E_0 when changing the electron energy E, which manifests itself in the appearance of the imaginary part of ψ. The distribution of resistance P(ρ) has no singularity at the point E_0, and the transition looks unobservable in the electron disordered systems. However, the theory of 1D localization is immediately applicable to propagation of waves in single-mode optical waveguides. The optical methods are more efficient and provide possibility to measure phases ψand χ. On the one hand, it makes observable the phase transition in the distribution P(ψ), which can be considered as a 'trace' of the mobility edge remaining in 1D systems. On the other hand, observability of the phase χmakes actual derivation of its evolution equation, which is presented below. Relaxation of the distribution P(χ) to the limiting distribution P_\infty(χ) at L\to\infty is described by two exponents, whose exponentials have jumps of the second derivative, when the energy E is changed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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