Spin-orbital Kondo decoherence by environmental effects in capacitively coupled quantum dot devices

TL;DR

This paper investigates how environmental electromagnetic noise affects the coherence and performance of a capacitively coupled double quantum-dot device used for quantum computing, focusing on the spin-orbital Kondo effect.

Contribution

It provides a detailed analysis of the impact of environmental impedance on the Kondo effect and device coherence, including a phase diagram and energy scale calculations.

Findings

Environmental impedance critically influences low-energy properties.

The phase diagram reveals regimes of coherent and decoherent transport.

Kondo temperature scales are affected by environmental factors.

Abstract

Strong correlation effects in a capacitively coupled double quantum-dot setup were previously shown to provide the possibility of both entangling spin-charge degrees of freedom and realizing efficient spin-filtering operations by static gate-voltage manipulations. Motivated by the use of such a device for quantum computing, we study the influence of electromagnetic noise on a general spin-orbital Kondo model, and investigate the conditions for observing coherent, unitary transport, crucial to warrant efficient spin manipulations. We find a rich phase diagram, where low-energy properties sensitively depend on the impedance of the external environment and geometric parameters of the system. Relevant energy scales related to the Kondo temperature are also computed in a renormalization-group treatment, allowing to assess the robustness of the device against environmental effects.