论文标题
通过两级系统的光激发产生的声子量子状态的熵动力学
Entropy Dynamics of Phonon Quantum States Generated by Optical Excitation of a Two-Level System
论文作者
论文摘要
在量子物理学中，两个原型模型系统由于其广泛的应用而脱颖而出。这些是两级系统（TLS）和谐波振荡器。前者通常是限制电荷或自旋系统的理想模型，后者是晶格振动的理想模型，即声子。在这里，我们将这两个系统融合在一起，这导致了许多引人入胜的物理现象。实际上，我们考虑了TLS的不同光激励和衰减场景，重点是将单个声子模式的生成动力学与TLS耦合。特别强调系统的不同部分的熵，主要是声子。虽然没有任何衰减，但整个系统始终处于纯状态，导致熵消失，但单个部分之间的复杂相互作用导致各自的纠缠熵和它们的非平凡动态。考虑到TLS的衰减会导致完整系统的非呈现熵及其动态中的其他方面。我们证明，熵行为的所有方面都可以追溯到状态的纯度，并通过相位空间中的声子函数进行了说明。
In quantum physics, two prototypical model systems stand out due to their wide range of applications. These are the two-level system (TLS) and the harmonic oscillator. The former is often an ideal model for confined charge or spin systems and the latter for lattice vibrations, i.e., phonons. Here, we couple these two systems, which leads to numerous fascinating physical phenomena. Practically, we consider different optical excitations and decay scenarios of a TLS, focusing on the generated dynamics of a single phonon mode that couples to the TLS. Special emphasis is placed on the entropy of the different parts of the system, predominantly the phonons. While, without any decay, the entire system is always in a pure state, resulting in a vanishing entropy, the complex interplay between the single parts results in non-vanishing respective entanglement entropies and non-trivial dynamics of them. Taking a decay of the TLS into account leads to a non-vanishing entropy of the full system and additional aspects in its dynamics. We demonstrate that all aspects of the entropy's behavior can be traced back to the purity of the states and are illustrated by phonon Wigner functions in phase space.
