Zero-threshold correlated-photon laser with a single trapped atom in a bimodal cavity

TL;DR

This paper proposes a theoretical scheme for generating entangled photon pairs with zero threshold using a single atom in a bimodal cavity, highlighting the roles of coherent and incoherent pumping in entanglement and amplification.

Contribution

It introduces a novel bimodal cavity setup with a single atom that enables entangled photon-pair generation without a threshold, emphasizing the interplay of coherent and incoherent processes.

Findings

Entangled photon pairs are generated only with low incoherent pump levels and coherent drives.

Incoherent pumping can amplify cavity fields and entangled pairs when combined with coherent drives.

Strong-coupling cavity QED exhibits oscillations in HBT functions indicating complex quantum dynamics.

Abstract

We demonstrate theoretically the feasibility of correlated entangled photon-pair generation with vanishing threshold in a bimodal cavity setup that uses a single V-type three level atom pumped by dual incoherent sources and driven by two coherent fields. The photon-pair is shown to be entangled only for low levels of the incoherent pumps and owes its origin solely to the coherent drives. Our results show that the dual incoherent pumping with no coherent drive can lead to amplification of the cavity fields with strong inter-mode antibunching but no entanglement. Though only coherent drives with no incoherent pumping can produce entangled photon-pairs, the entangled cavity fields can not be amplified beyond a certain limit using only coherent drives. However, the use of even small incoherent pumping in the presence of the coherent drives can amplify the generated entangled photon-pairs significantly. We analyse our results in terms of an interplay between coherent and incoherent processes involving cavity-dressed states. Both the inter- and intra-mode HBT functions exhibit temporal oscillations in the strong-coupling cavity QED regime. Our theoretical scheme for the generation of nonclassical and entangled photon pairs may find interesting applications in quantum metrology and quantum information science.