Approaching multichannel Kondo physics using correlated bosons: Quantum phases and how to realize them

TL;DR

This paper explores how multichannel Kondo physics can be realized with correlated bosons, analyzing phase diagrams and phase transitions in systems involving ultracold atoms or superconducting nanowires coupled to quantum dots.

Contribution

It introduces physical setups for realizing multichannel Kondo effects with bosonic systems and maps out their phase diagrams including critical points and phase transitions.

Findings

Multichannel Kondo states are stable over a wide parameter range.

Two nontrivial phase transitions are identified involving Kondo screening and correlations.

A self-dual multicritical point where phase transitions coalesce.

Abstract

We discuss how multichannel Kondo physics can arise in the setting of a localized level coupled to several bosonic Tomonaga-Luttinger liquid leads. We propose one physical realization involving ultracold bosonic atoms coupled to an atomic quantum dot, and a second, based on superconducting nanowires coupled to a Cooper-pair box. The corresponding zero-temperature phase diagram is determined via an interplay between Kondo-type phenomena arising from the dot and the consequences of direct inter-lead hopping, which can suppress the Kondo effect. We demonstrate that the multichannel Kondo state is stable over a wide range of parameters. We establish the existence of two nontrivial phase transitions, involving a competition between Kondo screening at the dot and strong correlations either within or between the leads (which respectively promote local number- and phase-pinning). These transitions coalesce at a self-dual multicritical point.