Beyond Hubbard: the role of correlated hopping interaction in superconductors and quantum dot devices

TL;DR

This paper explores how correlated hopping interactions influence superconducting phase transitions near Mott insulators and affect transport properties in quantum dot devices, revealing signatures in conductance changes.

Contribution

It introduces the impact of correlated hopping interactions beyond the Hubbard model on superconductivity and quantum dot transport, highlighting their role in phase transitions and conductance signatures.

Findings

Correlated hopping drives the superconducting phase transition.

CH modifies spectral properties near the Mott transition.

Conductance changes reveal the presence and sign of CH interaction.

Abstract

We investigate the role of strong Coulomb interactions beyond the standard Hubbard model in two distinct physical contexts. First, we analyze the superconducting phase transition occurring near the Mott metal-insulator transition. Second, we study transport properties of artificial nano-scale structures containing quantum dots coupled to external electrodes. In both cases, we focus on the impact of the correlated (assisted) hopping (CH) interaction. For superconductors, CH acts as a driving mechanism for the phase transition and modifies the spectral properties of the system. We present the evolution of the spectral function as the system approaches the Mott-type transition under varying model parameters. In quantum-dot-based devices, CH influences the tunneling amplitude between the dot and metallic leads. We demonstrate that the characteristic changes in the conductance of a normal metal-quantum dot-normal metal structure provide a clear signature of the presence and sign of CH interaction.