CHARGE FLUCTUATIONS UNDER THE COULOMB-BLOCKADE CONDITIONS

We study the Coulomb blockade in a quantum dot connected to a bulk lead by a single-mode quantum point contact. If the transmission coefficient of the contact is close to unity, the ground state energy and the average charge in the dot have small corrections oscillating as functions of gate voltage. These oscillations can be observed by measuring the capacitance between the gate and the lead. Near the points where the dot charge is half-integer the capacitance shows a non-analytic behavior identical to the non-Fermi-liquid susceptiblity of a two-channel spin-1/2 Kondo model.