Electromagnetically Induced Transparency of Interacting Rydberg Atoms with Two-Body dephasing

We study electromagnetically induced transparency of a ladder type configuration in ultracold atomic gases, where the upper level is an electronically highly excited Rydberg state. We study a scenario where both dispersive and dissipative long-range interactions between Rydberg atoms are present. This is motivated by recent experimental discovery, where molecular transitions cause an effective two-body dephasing process. It has been shown that long-range van der Waals interactions suppress simultaneous excitations of multiple Rydberg atoms within a blockade volume. We show that the nonlocal, two-body dissipative process enhances the excitation blockade. Through numerical and approximately analytical calculations, we show that transmission of the probe field is reduced drastically in the transparent window, which is accompanied by stronger photon-photon anti-bunching. Around the Autler-Townes splitting, photon bunching is amplified by the two-body dephasing, while the transmission is largely unaffected.