$\eta$ Pairing of Light-Emitting Fermions: Nonequilibrium Pairing Mechanism at High Temperatures

TL;DR

This paper demonstrates that strongly interacting fermionic atoms can develop nonequilibrium $ta$-pairing superfluid correlations at high temperatures due to spontaneous emission, enabling coherent pairing even from uncorrelated initial states.

Contribution

It introduces a novel nonequilibrium pairing mechanism in fermionic systems driven by spontaneous emission, leading to $ta$-pairing correlations at high temperatures.

Findings

Nonequilibrium $ta$-pairing correlations emerge in driven fermionic systems.

Pair correlations can form from an uncorrelated infinite-temperature state.

Experimental feasibility with optical lattice fermions is discussed.

Abstract

Strongly interacting fermionic atoms are shown to develop $\eta$-pairing superfluid correlations in a nonequilibrium steady state in the presence of spontaneous emission of light from atoms. On the basis of the Hubbard model subject to spontaneous decay between internal spin states, we show that prohibition of radiative decay due to the Pauli exclusion principle and destructive interference between doublon-decay processes lead to nonequilibrium $\eta$ pairing. Because of the non-thermal nature of the steady state, pair correlations arise even from a completely uncorrelated infinite-temperature initial state, allowing coherent atom pairs to be formed at high temperatures. Experimental implementation with fermionic atoms in an optical lattice is discussed.