Mesoscopic quantum transport: Resonant tunneling in the presence of a strong Coulomb interaction

Abstract

Coulomb blockade phenomena and quantum fluctuations are studied in mesoscopic\nmetallic tunnel junctions with high charging energies. If the resistance of the\nbarriers is large compared to the quantum resistance, transport can be\ndescribed by sequential tunneling. Here we study the influence of quantum\nfluctuations. They are important when the resistance is small or the\ntemperature very low. A real-time approach is developed which allows the\ndiagrammatic classification of ``inelastic resonant tunneling'' processes where\ndifferent electrons tunnel coherently back and forth between the leads and the\nmetallic island. With the help of a nonperturbative resummation technique we\nevaluate the spectral density which describes the charge excitations of the\nsystem. From it physical quantities of interest like current and average charge\ncan be deduced. Our main conclusions are: An energy renormalization leads to a\nlogarithmic temperature dependence of the renormalized system parameters. A\nfinite lifetime broadening can change the classical picture drastically. It\ngives rise to a strong flattening of the Coulomb oscillations for low\nresistances, but in the Coulomb blockade regime inelastic electron cotunneling\npersists. The temperature where these effects are important are accessible in\nexperiments.\n

Keywords

Affiliated Institutions

• Karlsruhe Institute of Technology DE

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