COULOMB OSCILLATIONS IN PARTIALLY OPEN QUANTUM DOTS

We report tunneling measurements of the Coulomb blockade in a single q uantum dot at zero magnetic field and dilution refrigerator temperatur es with weak tunneling from the dot to one lead (the 'closed' lead, co nductance G(closed)) and strong tunneling to the other lead (the 'open ' lead, conductance G(open)). We observe suppression of the Coulomb os cillations with G(open) approximate to 2e(2)/h, and then see the oscil lations return for G(open) > 2e(2)/h. The oscillations show a striking ly lower threshold temperature at G(open) approximate to 2e(2)/h than for greater or lesser G(open). (C) 1996 Academic Press Limited