ENERGY-AVERAGED WEAK-LOCALIZATION IN CHAOTIC MICROCAVITIES

We have fabricated ballistic cavities from a two-dimensional GaAs elec tron gas in which the Fermi energy. can be varied independent of cavit y shape. For each cavity, we have measured the magnetoconductance G(B) of many individual members of an ensemble, with each member labeled b y its Fermi energy. We find that G(B) of a single ensemble member does not always display the minimum at B = 0 which is the signature of wea k localization. By averaging over our ensemble, we have obtained the e nergy-averaged weak-localization effect for each cavity shape. The ave rage result does display the expected minimum at B = 0. We compare our results with recent analytical theories and numerical simulations of weak localization in cavities with chaotic classical scattering and fi nd good quantitative agreement.