Coulomb blockade at almost perfect transmission

TL;DR

This paper investigates Coulomb blockade phenomena in a quantum dot with near-perfect transmission, revealing persistent oscillations and Kondo-like behavior even at high transmission levels, with specific thermodynamic singularities.

Contribution

It demonstrates that Coulomb blockade oscillations persist at almost perfect transmission and identifies Kondo-like non-analytic behavior in thermodynamic properties.

Findings

Coulomb blockade oscillations exist below unity transmission.

Thermodynamic characteristics show non-analytic behavior at half-integer charge points.

Capacitance exhibits periodic logarithmic singularities as a function of gate voltage.

Abstract

We study the equilibrium properties of a quantum dot connected to a bulk lead by a single-mode quantum point contact. The ground state energy and other thermodynamic characteristics of the grain show periodic dependence on the gate voltage (Coulomb blockade). We consider the case of almost perfect transmission, and show that the oscillations exist as long as the transmission coefficient of the contact is less than unity. Near the points where the dot charge is half-integer the thermodynamic characteristics show a non-analytic behavior identical to that of the two-channel spin-1/2 Kondo model. In particular, at any transmission coefficient the capacitance measured between the gate and the lead shows periodic logarithmic singularities as a function of the gate voltage.