Seo, Wontaek. et al. "Realization of a biopolar atomic Solc filter in the cavity-QED microlaser." Physical Review A 81.5 (2010)" 053824.We report experimental realization of a rudimentary atomicŠolc filter, recently proposed by Hong et al. [Opt. Express 17, 15455 (2009)]. It is realized by employing a bipolar atom-cavity coupling constant in the cavity-QED microlaser operating with a TEM 10 mode in a strong coupling regime. The polarity flip in the coupling constant dramatically changes the photoemission probability of a two-level atom relative to unipolar coupling, resulting in multiple narrow emission bands in the detuning curve of the microlaser mean photon number. The observed resonance curves are explained well by a two-step, three-dimensional, geodesic-like motion of the Bloch vector in the semiclassical limit.

We report an experimental demonstration of the nonclassical stationary light pulse (SLP) in a cold atomic ensemble. A single collective atomic excitation is created and heralded by detecting a Stokes photon in the spontaneous Raman scattering process. The heralded single atomic excitation is converted into a single stationary optical excitation or the single-photon SLP, whose effective group velocity is zero, effectively forming a trapped single-photon pulse within the cold atomic ensemble. The single-photon SLP is then released from the atomic ensemble as an anti-Stokes photon after a specified trapping time. The second-order correlation measurement between the Stokes and anti-Stokes photons reveals the nonclassical nature of the single-photon SLP. Our work paves the way toward quantum nonlinear optics without a cavity.