Adding Photonic Entanglement to Superradiance by Using Multilevel Atoms

TL;DR

This paper demonstrates that superradiance from multilevel atoms can produce entangled photonic states in frequency, driven by atomic superposition and internal degeneracies, offering a promising source of entangled photons.

Contribution

It introduces a novel mechanism for generating entangled photons via superradiance in multilevel atomic ensembles, highlighting the role of internal degeneracies and virtual transitions.

Findings

Entangled photonic states are produced in superradiance from multilevel atoms.

Internal degeneracies induce complex virtual transitions creating interatomic correlations.

Steady-state correlations can exhibit beating phenomena due to virtual transitions.

Abstract

We show here that the photonic states emitted by ensembles of multilevel atoms via a superradiance process exhibit entanglement in the modal (frequency) degree of freedom, making this collective emission process a favorable candidate for a fast, bright and deterministic source of entangled photons. This entanglement is driven by two mechanisms: (i) selective excitation of the atomic ensemble to a superposition state and (ii) degeneracies of the optical transitions due to internal structure of the emitting atoms. The latter induces intricate non-radiative virtual transitions in the ensemble, which create interatomic correlations that are imprinted onto the emitted photons. One of the important outcomes of this complexity is the generation of mode-independent entangled multiphoton states. In addition, we study the dynamics of the correlations of the superradiating multilevel atom ensembles, and demonstrate a case where they exhibit beating in steady-state due to the aforementioned virtual transitions.