Phonon-induced pairing in quantum dot quantum simulator

TL;DR

This paper investigates how phonon interactions induce pairing in a quantum dot system modeled by the Hubbard-Holstein Hamiltonian, revealing a transition from Mott insulator to polaronic states with pairing.

Contribution

It demonstrates the phase diagram of a four-quantum-dot system coupled to phonons, highlighting phonon-induced pairing and phase transitions in a quantum simulation context.

Findings

Transition from Mott insulator to polaronic state

Emergence of pairing correlations

Breaking of translational symmetry

Abstract

Quantum simulations can provide new insights into the physics of strongly correlated electronic systems. A well studied system, but still open in many regards, is the Hubbard-Holstein Hamiltonian, where electronic repulsion is in competition with attraction generated by the electron-phonon coupling. In this context we study the phase diagram of four quantum dots in a suspended carbon nanotube and coupled to its flexural degrees of freedom. The system is described by a Hamiltonian of the Hubbard-Holstein class, where electrons on different sites interact with the same phonon. We find that the system presents a transition from the Mott insulating state to a polaronic state, with the appearance of pairing correlations and the breaking of the translational symmetry. Our study shows that this system thus constitutes a relevant example of a correlated system that could be studied by experimental realization.