Two-photon bound states in Rydberg gases

Matthias Moos, Johannes Otterbach, Dominik Muth +1 more

Gerard T. Higgins

Matthias Moos, Razmik G. Unanyan, Michael Fleischhauer

We consider the propagation of photons in a gas of Rydberg atoms under conditions of electromagnetically induced transparency, where they form strongly interacting massive particles, termed Rydberg polaritons. Depending on the strength of the van der Waals-type interactions of the atoms either bunching or antibunching of photons can be observed when driving the atoms off-resonantly. The bunching is associated with the formation of bound states. We employ a Green's function approach and numerical wave-function simulations to analyze the conditions for the creation and the dynamics of these photonic molecules and their interplay with the scattering continuum which can also show photon bunching. Analytic solutions of the pair-propagation problem obtained from a pseudopotential approximation and verified numerically provide a detailed understanding of bound and scattering states. We find that the scattering contributions acquire asymptotically a robust relative phase which can be employed to separate bound state and scattering contributions by a homodyne detection scheme.

Guoqi Bian, Biao Shan, Lianghui Huang +1 more

We report the measurement of the electromagnetically induced transparency (EIT) with Rydberg states in ultracold 40 K Fermi gases, which is obtained through a two-photon process with the ladder scheme.Rydberg-EIT lines are obtained by measuring the atomic losses instead of the transmitted probe beam.Based on the laser frequency stabilization locking to the superstable cavity, we study the Rydberg-EIT line shapes for the 37s and 35d states.We experimentally demonstrate the significant change in the Rydberg-EIT spectrum by changing the principal quantum number of the Rydberg state (n = 37=52 and l = 0).Moreover, the transparency peak position shift is observed, which may be induced by the interaction of the Rydberg atoms.This work provides a platform to explore many interesting behaviors involving Rydberg states in ultracold Fermi gases.

Hyo Min Kwak, Taek Jeong, Yoon‐Seok Lee +1 more

Qiyu Liang, Aditya V. Venkatramani, Sergio Cantu +7 more

Bound states of massive particles, such as nuclei, atoms, or molecules, constitute the bulk of the visible world around us. By contrast, photons typically only interact weakly. We report the observation of traveling three-photon bound states in a quantum nonlinear medium where the interactions between photons are mediated by atomic Rydberg states. Photon correlation and conditional phase measurements reveal the distinct bunching and phase features associated with three-photon and two-photon bound states. Such photonic trimers and dimers possess shape-preserving wave functions that depend on the constituent photon number. The observed bunching and strongly nonlinear optical phase are described by an effective field theory of Rydberg-induced photon-photon interactions. These observations demonstrate the ability to realize and control strongly interacting quantum many-body states of light.