Linear and nonlinear susceptibilities of a decoherent two-level system
Linear and nonlinear susceptibilities of a decoherent two-level system
复制标题
退相干二能级系统的线性和非线性磁化率
DOI：
10.1103/physrevb.61.4636
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发表时间：
2000
影响因子：
3.7
通讯作者：
G. Levine
中科院分区：
文献类型：
--
作者：
G. Levine
计算了一个二能级系统向退相干态跃迁时的线性和非线性动力学极化率。类似于超导的Goverer-Tinkham-Ferrell求和规则，线性极化率中的谱权重从有限频率的共振不断地转移到接近零的频率，对应于热力学极限中的对称性破缺。由于这个原因，本模型(Mermin模型)的行为与自旋-玻色子模型有很大不同。与双光子吸收相对应的三阶非线性极化率作为环境耦合的函数具有意想不到的非单调行为，在模型的退相干阶段达到最大。线性极化率和非线性极化率都可以用通用形式表示。
The linear and nonlinear dynamical susceptibilities of a two level system are calculated as it undergoes a transition to a decoherent state. Analogously to the Glover-Tinkham-Ferrell sum rule of superconductivity, spectral weight in the linear susceptibility is continuously transferred from a finite frequency resonance to nearly zero frequency, corresponding to a broken symmetry in the thermodynamic limit. For this reason, the behavior of the present model (the Mermin model) differs significantly from the spin-boson model. The third order nonlinear susceptibility, corresponding to two-photon absorption, has an unexpected non-monotonic behavior as a function of the environmental coupling, reaching a maximum within the decoherent phase of the model. Both linear and nonlinear susceptibilities may be expressed in a universal form.