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

Stephen Powell·Subir Sachdev
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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.

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Stephen Powell, Subir Sachdev. 2006-09-27. Excited state spectra at the superfluid-insulator transition out of paired condensates. https://doi.org/10.1103/physreva.75.031601

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