Semiclassical theory of quantum chaotic transport: Phase-space splitting, coherent backscattering, and weak localization

We investigate transport properties of quantized chaotic systems in the short-wavelength limit. We focus on noncoherent quantities such as the Drude conductance, its sample-to-sample fluctuations, shot noise, and the transmission spectrum, as well as coherent effects such as weak localization. We show how these properties are influenced by the emergence of the Ehrenfest time scale tau(E). Expressed in an optimal phase-space basis, the scattering matrix acquires a block-diagonal form as tau(E) increases, reflecting the splitting of the system into two cavities in parallel, a classical deterministic cavity (with all transmission eigenvalues either 0 or 1) and a quantum mechanical stochastic cavity. This results in the suppression of the Fano factor for shot noise and the deviation of sample-to-sample conductance fluctuations from their universal value. We further present a semiclassical theory for weak localization which captures nonergodic phase-space structures and preserves the unitarity of the theory. Contrarily to our previous claim [Phys. Rev. Lett. 94, 116801 (2005)], we find that the leading off-diagonal contribution to the conductance leads to the exponential suppression of the coherent backscattering peak and of weak localization at finite tau(E). This latter finding is substantiated by numerical magnetoconductance calculations.