Imaginary Gauge Transformation in Momentum Space and Dirac Exceptional Point
Imaginary Gauge Transformation in Momentum Space and Dirac Exceptional Point
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动量空间中的虚规范变换与狄拉克例外点
DOI：
10.1103/physrevlett.129.243901
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发表时间：
2022
影响因子：
8.6
通讯作者：
Ge, Li
中科院分区：
文献类型：
--
作者：
Rivero, Jose H. D.;Feng, Liang;Ge, Li
虚数规范变换是非厄米集肤效应的核心。在这里，我们证明这种变换也可以在动量空间中执行，这表明某些增益和损耗调制系统在其宇称时间 () 对称相位中相当于具有真实势的埃尔米特系统。我们对动量空间的分析还区分了同一系统中的两种类型的异常点 (EP)。除了增益和损耗不断增加而导致转变的传统类型之外，我们还发现了在混合维度上连接在狄拉克 EP 处的实值能带，其中包括增益和损耗强度的空间维度和合成维度。
An imaginary gauge transformation is at the core of the non-Hermitian skin effect. Here, we show that such a transformation can be performed in momentum space as well, which reveals that certain gain- and loss-modulated systems in their parity-time () symmetric phases are equivalent to Hermitian systems with real potentials. Our analysis in momentum space also distinguishes two types of exceptional points (EPs) in the same system. Besides the conventional type that leads to atransition upon the continuous increase of gain and loss, we find real-valued energy bands connected at a Dirac EP in hybrid dimensions, consisting of a spatial dimension and a synthetic dimension for the gain and loss strength.