Playing Quantum Billiard in Ferroelectrics

1. Playing Quantum Billiard in Ferroelectrics VolkmarDierolf, Lehigh University, DMR 1008075 Quantum Scattering events such as Raman scattering in ordered crystalline solids obey energy and momentum conservation laws for the involved quantum particles (photons and phonons), just as in the collision between the que and object balls in pool billiard. In pool, this situation becomes more complicated as soon as the banks are involved. In an upcoming Optics Letter, Stone and Dierolf could show that in a ferroelectric material, the domain wall plays the role of the bank such that phonons bounce of the domain wall and propagate sidewise although the photon bounces straight back. This interesting fundamental observation was made possible be highest spectral resolution in an confocal microscope and a favorable circumstance in the material, namely that in lithium niobate and tantalate the phonon’s energy depends on propagation directions. “Rules of the Game” Regular (center of table) At domain wall (bank shot) Domain wall (“bank”) Experimental Manifestation