Direct Measurement of the Effective Initial Tipping Angle in Superfluorescence

Abstract

We report the first direct measurement of the effective initial tipping angle ${\theta }_0$ in superfluorescence. A coherent pulse of small area $\theta$, resonant on the superfluorescence transition, is injected into a completely inverted sample of cesium atoms and the delay of the out-put pulse is measured as a function of $\theta$. The value of ${\theta }_0$ obtained agrees in essence with $\frac{2}{{\mathrm{}\left(N\right)\mathrm{}}^{\frac{1}{2}}}$. The latter value is predicted by recent theories which consider the quantum initiation of superfluorescence and which take propagation effects into account.