Effect of a voltage probe on the phase-coherent conductance of a ballistic chaotic cavity

The effect of an invasive voltage probe on the phase-coherent conduction through a ballistic chaotic cavity is investigated by random-matrix theory. The entire distribution P(G) of the conductance G is computed for the case that the cavity is coupled to source and drain by two point contacts with a quantized conductance of 2${\mathit{e}}^2$/h, both in the presence (β=1) and absence (β=2) of time-reversal symmetry. The loss of phase coherence induced by the voltage probe causes a crossover from P(G)∝${\mathit{G}}^{\mathrm{-}1+\mathrm{\beta }/2\mathrm{}}$ to a Gaussian centered at G=${\mathit{e}}^2$/h with a β-dependent width.