Excited state spectra at the superfluid-insulator transition out of paired condensates

TL;DR

This paper investigates the excitation spectra during the superfluid-insulator transition in systems with paired particles, revealing the critical dynamics governed by impurity models and providing insights relevant to ultracold atoms and high-temperature superconductors.

Contribution

It introduces a novel impurity-based framework to analyze excitation spectra at the superfluid-insulator transition involving paired condensates.

Findings

Critical exponents derived via renormalization group analysis.

Dynamics controlled by a quantum impurity problem.

Applications to ultracold atoms and cuprate materials.

Abstract

We describe gapped single-particle and collective excitations across a superfluid to insulator quantum phase transition of particles (bosons or fermions) in a periodic potential, with an even number of particles per unit cell. We demonstrate that the dynamics is controlled by a quantum impurity problem of a localized particle interacting with the bulk critical modes. Critical exponents are determined by a renormalization group analysis. We discuss applications to spin oscillations of ultracold atoms in optical lattices, and to the electronic phases in the cuprate and related compounds.