Phase Modulation of Atomic de Broglie Waves

Cesium atoms prepared in a state of well-defined total energy have been reflected from a vibrating mirror, causing the matter waves to be phase modulated. The mirror is an evanescent light wave whose intensity is modulated in time at a frequency $\nu$ in the range 0 to 2 MHz; the atoms are reflected at normal incidence. The resulting beam consists of a “carrier” plus various sidebands corresponding to de Broglie waves propagating at different velocities. The precision and flexibility of this technique make it a promising tool in atom optics.