论文标题
来自Anharmonic Phon子的预测和观察
Prediction and Observation of Intermodulation Sidebands from Anharmonic Phonons
论文作者
论文摘要
一种类似于最近用于光学机械模型的量子Langevin模型，用于预测跨调节声子侧带（IPS）。从头开始计算岩石NABR中的Anharmonic声子，将这些光谱特征显示为“多体效应”。在300K处的NABR晶体上的现代非弹性中子散射测量显示，从预测的上IPS处高声子能量处的扩散强度。新特征的横向光学（TO）部分源自横向声（TA）和声子之间的声子调制。纵向光（LO）光谱特征源自TA模式和晶格模式之间的三频耦合。伴侣下IPS被证明是“内在局部模式”。与热浴的相互作用扩大并重新分布IPS对的光谱重量。这些侧带是非谐度和量子噪声的探针，它们源自NABR中的声子之间的相互作用。
A quantum Langevin model, similar to models used recently for optomechanics, was used to predict intermodulation phonon sidebands (IPS). Ab initio calculations of anharmonic phonons in rocksalt NaBr showed these spectral features as "many-body effects". Modern inelastic neutron scattering measurements on a crystal of NaBr at 300K revealed diffuse intensity at high phonon energy from a predicted upper IPS. The transverse optical (TO) part of the new features originates from phonon intermodulation between the transverse acoustic (TA) and TO phonons. The longitudinal optical (LO) spectral features originate from three-phonon coupling between the TA modes and the TO lattice modes. The partner lower IPS proves to be an "intrinsic localized mode". Interactions with the thermal bath broaden and redistribute the spectral weight of the IPS pair. These sidebands are a probe of anharmonicity and quantum noise, which originate from interactions between the phonons in NaBr.
