背景辐射中负热容量系统的质量演化讨论及Runge-Kutta法数值模拟

以黑洞为例,在不考虑满足幺正性的情况下得到了在背景辐射中Schwarzschild黑洞的质量随时间变化的微分方程,并对该方程进行了必要的研究和讨论,作为对《新概念物理教程.力学》和《新概念物理教程.热学》中提到的负热容量系统的不稳定性的另一个注释.文章最后用Runge-Kutta法数值模拟了Schwarzschild黑洞的质量演化过程,使广大学生能够更直观地理解这一过程.     

Nonreciprocal Phonon Laser in an Asymmetric Cavity with an Atomic Ensemble

Phonon lasers, as a novel kind of lasers for generating coherent sound oscillation, has attracted extensive attention. Here, we theoretically propose a nonreciprocal phonon laser in a hybrid optomechanical system, which is composed of an asymmetric Fabry–Pérot cavity, an ensemble of N identical two-level atoms, and a mechanical oscillator. The effective driving amplitude related to driving direction leads to an obvious difference in mechanical gain and threshold power, bringing about a nonrecipr...