Effect of the Electromagnetic Environment on the Coulomb Blockade in Ultrasmall Tunnel Junctions

M. H. Devoret, D. Esteve, H. Grabert, G.-L. Ingold, H. Pothier und C. Urbina

Phys. Rev. Lett. 64, 1824–1827 (1990) DOI: 10.1103/PhysRevLett.64.1824

The current-voltage characteristic of an ultrasmall tunnel junction is calculated for arbitrary frequency dependence of the impedance presented to the junction by its electromagnetic environment. It is shown that the Coulomb blockade of tunneling is washed out by quantum fluctuations of the charge on the junction capacitor except for ultrahigh-impedance environments. Two simple cases where the environment can be treated as an inductor or resistor are examined in detail. Effects of finite temperatures are discussed.