WEAK-LOCALIZATION AND INTEGRABILITY IN BALLISTIC CAVITIES

We demonstrate the existence of an interference contribution to the average magnetoconductance, GBAR(B), of ballistic cavities and use it to test the semiclassical theory of quantum billiards. GBAR(B) is qualitatively different for chaotic and regular cavities (saturation versus linear increase) which is explained semiclassically by the differing classical distribution of areas. The magnitude of GBAR(B) is poorly explained by the semiclassical theory of coherent backscattering (elastic enhancement factor); interference between trajectories which are not exactly time reversed must be included.