| This thesis consists of two parts. First we discuss how dephasing affects the distribution of the dc current pumped through a chaotic quantum dot. In our theoretical model, dephasing is introduced by the addition of a voltage probe. The probability density and variance of the pumped current are calculated, for several amounts of dephasing. We derive a simple formula for the variance in the limit of large dephasing. While dephasing eventually suppresses the dc current through the dot, we also find that, for a quantum dot with single-mode point contacts, a small amount of dephasing actually decreases the likelihood of a zero pumped current.; In the second part we analyze the effects of spin-orbit coupling on electronic transport through a quantum dot fabricated in a GaAs heterostructure. We take into account spin-orbit coupling that is due to the lack of inversion symmetry in the GaAs crystal (Dresselhaus spin-orbit coupling) and to the electric field confining the electrons to the two dimensional electron gas (Rashba spin-orbit coupling). We also consider the effects of a perpendicular and parallel magnetic field. We argue that spin-orbit effects may become important in the presence of a large parallel magnetic field B∥, even if they are negligible for B∥ = 0.; Using random matrix theory the average and the covariance of the conductance are calculated, for general values of spin-orbit coupling and magnetic field, in the limit of a large number of conducting channels. The conditions for the presence weak (anti-)localization are studied. Our results agree well with detailed experiments performed by Zumbühl et al., who used our expressions to fit their data.; We predict an increase in conductance fluctuations at finite perpendicular field due to spin-orbit coupling. We study the correlation of the conductance in perpendicular field, in the presence of spin-orbit coupling and a parallel field. We obtain conditions for asymmetry between the conductance at opposite fields B⊥ and −B ⊥, for which both non-zero spin-orbit coupling and a parallel magnetic field are necessary. The case of spatially non-uniform spin-orbit coupling is considered, leading to a proposal for tunable spin-orbit coupling in a quantum dot. |
