Probability distributions of transport observables in quantum dots: crossover between universal ensembles

We study the effect on the probability distributions of the conductance and shot-noise power of breaking time-reversal symmetry in quantum dots with ideal contacts and small number of scattering channels. The distributions were found numerically by employing the Landauer–Büttiker scattering approach and random-matrix theory and are presented as a function of the number of propagating channels and the symmetry breaking parameter. Universal broad distributions are found throughout the crossover region.