Parity-dependent Kondo effect in ultrasmall metallic grains

We study the Kondo effect in an ultrasmall metallic grain, i.e. small enough to have a discrete energy-level spectrum, by calculating the susceptibility chi of the magnetic impurity. Our quantum Monte Carlo simulations, and analytic solution of a simple model, show that the behavior changes dramatically depending on whether the number of electrons in the grain is even or odd. We suggest that the measurements of chi provide an effective experimental way of probing the grain's number parity.