DIRECT MEASUREMENT OF THE EFFECTIVE INITIAL TIPPING ANGLE IN SUPERFLUORESCENCE

We report the first direct measurement of the effective initial tipping angle 0 in superfluorescence. A coherent pulse of small area, 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. The value of 0 obtained agrees in essence with 2(N)12. The latter value is predicted by recent theories which consider the quantum initiation of superfluorescence and which take propagation effects into account. © 1979 The American Physical Society.