Optical Linear Absorption of a Two Level System

In this code, differential equation for optical polarization is solved.

The optical polarization of a two level system obeys a differential equation , dp/dt= i/h(wR)p + i/h mu E - gamm P
, where wR is the resonant frequency, E is the electric field and gamm is a dephasing constant. Here E is a Gaussian
enveloped chirp signal while other parameters can be easily changed. The differential equation is solved via 4th order Runge Kutta method to get p(t) and its linear absorption spectra P(omega) is plotted.