Observability of the Coulomb Blockade in Single Tunnel Junctions

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

Physica B 165&166, 977–978 (1990) DOI: 10.1016/S0921-4526(09)80074-4

The finite temperature I-V-characteristic of a normal tunnel junction coupled to its electromagnetic environment is calculated. It is shown that due to quantum fluctuations of the charge the Coulomb gap is only observable provided the impedance Z(ω) of the environment exceeds the resistance quantum RQ=h/2e2. The observability of the Coulomb blockade in single junctions is severely limited by finite temperature effects. Apart from general results for an environment with arbitrary impedance, detailed predictions are presented for a case of practical interest where the leads attached to the junction may be represented through a series inductance and a shunt capacitance.