  We investigate the two-terminal nonlinear conductance of a Coulomb-blockaded
quantum dot attached to chiral edge states. Reversal of the applied magnetic
field inverts the system chirality and leads to a different polarization
charge. As a result, the current--voltage characteristic is not an even
function of the magnetic field. We show that the corresponding magnetic-field
asymmetry arises from single-charge effects and vanishes in the limit of high
temperature.
