$\eta$--paired superconducting hidden phase in photodoped Mott insulators

TL;DR

This paper demonstrates that a metastable $ta$-pairing superconducting phase can be induced in a strongly repulsive fermionic Hubbard model through photodoping, with distinctive optical signatures that can be observed experimentally.

Contribution

It introduces a novel method to realize $ta$-pairing superconductivity via photodoping and explores its properties and experimental signatures.

Findings

The $ta$-pairing phase is induced by photodoping doublons and holes.

The phase exhibits ideal metallic optical conductivity with a delta function at zero frequency.

Distinct optical features, including negative conductivity at high frequencies, serve as experimental fingerprints.

Abstract

We show that a metastable $\eta$--pairing superconducting phase can be induced by photodoping doublons and holes into a strongly repulsive fermionic Hubbard model. The doublon-hole condensate originates from an intrinsic doublon-hole exchange interaction and does not rely on the symmetry of the half-filled Hubbard model. It extends over a wide range of doublon densities and effective temperatures. Different non-equilibrium protocols to realize this state are proposed and numerically tested. We also study the optical conductivity in the superconducting phase, which exhibits ideal metallic behavior, i.e., a delta function at zero-frequency in the conductivity, in conjunction with a negative conductivity at large frequencies. These characteristic optical properties can provide a fingerprint of the $\eta$-pairing phase in pump-probe experiments.