Decoherence and Dephasing in Kondo Tunneling through Double Quantum Dots

TL;DR

This paper investigates how charge fluctuations and dynamical gauge fluctuations cause decoherence and dephasing in Kondo tunneling through double quantum dots with even occupation, highlighting the role of SO(5) symmetry.

Contribution

It introduces a detailed analysis of decoherence and dephasing mechanisms in Kondo tunneling in DQDs, emphasizing the impact of dynamical gauge fluctuations and SO(5) symmetry.

Findings

Charge fluctuations induce transitions within the spin multiplet.

Decoherence and dephasing are caused by dynamical gauge fluctuations.

Different mechanisms affect ground state decoherence and finite temperature dephasing.

Abstract

We describe the mechanism of charge-spin transformation in a double quantum dot (DQD) with even occupation, where a time dependent gate voltage v(t) is applied to one of its two valleys, whereas the other one is coupled to the source and drain electrodes. The Kondo tunneling regime under strong Coulomb blockade may be realized when the spin spectrum of the DQD is formed by the ground state spin triplet and two singlet excitations. Charge fluctuations induced by v(t) result in transitions within the spin multiplet characterized by the SO(5) dynamical symmetry group. In a weakly non-adiabatic regime the decoherence, dephasing and relaxation processes affect Kondo tunneling. Each of these processes is caused by a special type of dynamical gauge fluctuations, so that one may discriminate between the decoherence in the ground state of a DQD and dephasing at finite temperatures.