# Modeling the pseudogap metallic state in cuprates: quantum disordered pair density wave

## TL;DR

This paper proposes a quantum-disordered pair density wave model as an effective description of the pseudogap metal in cuprates, explaining experimental observations like ARPES spectra and mid-infrared absorption.

## Contribution

It introduces a novel quantum-disordered PDW state with a small-pocket Fermi liquid and bosonic Mott insulator, providing new insights into the pseudogap phase.

## Key findings

- Electron spectral function shows a step function background consistent with ARPES data.
- Optical excitation across the boson gap explains mid-infrared absorption features.
- Model predicts a small insulating gap for charge 2e bosons.

## Abstract

We present a way to quantum-disorder a pair density wave, and propose it to be a candidate of the effective low-energy description of the pseudogap metal which may reveal itself in a sufficiently high magnetic field that suppresses the d-wave pairing. The ground state we construct is a small-pocket Fermi liquid with a bosonic Mott insulator in the density-wave-enlarged unit cell. At low energy, the charge density is mainly carried by charge 2e bosons, which develop a small insulating gap. As an intermediate step, we discuss the quantum disordering of a fully gapped superconductor and its excitation spectrum. In order to illustrate the concepts we introduce, we introduce a simplified 1D model which we solve numerically. We discuss a number of experimental consequences. The interplay between the electron and the small-gap boson results in a step function background in the electron spectral function which may be consistent with existing ARPES data. Optical excitation across the boson gap can explain the onset and the magnitude of the mid-infra-red absorption reported long ago.