Nonequilibrium Polaritonics - Nonlinear Effects and Optical Switching

具有状态相关噪声的非平衡系统中的稀有跃迁事件：应用于半导体超晶格中的随机电流开关

Rare Transition Events in Nonequilibrium Systems with State-Dependent Noise: Application to Stochastic Current Switching in Semiconductor Superlattices

利用最新的数学进展，给出了非平衡系统中罕见噪声驱动的跃迁事件的几何方法，并将计算最大似然跃迁曲线的算法推广到状态依赖噪声的情况。它被应用到半导体超晶格中的电子输运模型，以研究亚稳态电场分布之间的转换。当施加的电压$V$在$V_th$处的鞍结分叉附近变化时，初始亚稳态的平均寿命$<T>$被示出为像$log<T> \propto |V_th - V|^{3/2}$那样缩放为$V\to V_th$。

通过电子-振动散射模拟金属原子接触的双稳态电流诱导开关

Simulating bistable current-induced switching of metallic atomic contacts by electron-vibration scattering

本文结合DFT与非平衡格林函数方法，研究金属原子接触中由电流诱导振动激发的双稳态开关机制，并以单原子铅接触为例确定了可驱动构型转变的振动模式。

All-optical nonequilibrium pathway to stabilizing magnetic Weyl semimetals in pyrochlore iridates

Nonequilibrium many-body dynamics is becoming one of the central topics of modern condensed matter physics. Floquet topological states were suggested to emerge in photodressed band structures in the presence of periodic laser driving. Here we propose a viable nonequilibrium route without requiring coherent Floquet states to reach the elusive magnetic Weyl semimetallic phase in pyrochlore iridates by ultrafast modification of the effective electron-electron interaction with short laser pulses. Combining \textit{ab initio} calculations for a time-dependent self-consistent reduced Hubbard $U$ con…

二维铁磁器件中的自旋轨道转矩与磁化翻转

Spin-Orbit Torque and Magnetization Switching in 2D Ferromagnetic Devices

通过第一性原理计算研究范德华异质双层Cr3Te4/PtTe2中的非平衡自旋转矩，发现局域自旋感应产生类场转矩主导面内磁各向异性体系的翻转电流，并强调优化NM层自旋霍尔效应和FM层Rashba效应分别对垂直和面内磁各向异性翻转的重要性。

Cavity control of nonlinear phononics

Nonlinear interactions between phonon modes govern the behavior of vibrationally highly excited solids and molecules. Here, we demonstrate theoretically that optical cavities can be used to control the redistribution of energy from a highly excited coherent infrared-active phonon state into the other vibrational degrees of freedom of the system. The hybridization of the infrared-active phonon mode with the fundamental mode of the cavity induces a polaritonic splitting that we use to tune the nonlinear interactions with other vibrational modes in and out of resonance. We show that not only can …

Ultrafast, low-energy, all-optical switch in polariton waveguides

The requirement for optical-electrical-optical conversion of signals in optical technologies is often one of the majors bottleneck in terms of speed and energy consumption. The use of dressed photons (also called polaritons), that allows for intrinsic sizable interactions, could significantly improve the performances of optical integrated elements such as switches or optical gates. In this work we demonstrate the ultrafast switch of a laser coupled into a polaritonic waveguide triggered by an optical pulse resonant with the same dispersion but at a lower energy. Our experiments show two effect…