Phase breaking in ballistic quantum dots: Experiment and analysis based on chaotic scattering

We introduce two methods of extracting the rate of loss of electron phase coherence in ballistic quantum dot microstructures from statistical measures of magnetic-field-induced conductance fluctuation. The first method uses changes in the (magnetic-field) power spectrum of conductance fluctuations upon changing the average conductance through the dot. The second, based on a Hauser-Feshbach–like formula from nuclear physics, relates the phase-breaking rate to the amplitude of the conductance fluctuations. The two methods are then applied to experimental data from GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As quantum dots in the shape of a stadium billiard. Preliminary results give phase-breaking rates that are consistent with those previously found in quasiballistic GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As microstructures.