%0 Journal Article
%J Physical Review Letters
%D 2015
%T Coulomb bound states of strongly interacting photons
%A Mohammad F. Maghrebi
%A Michael Gullans
%A P. Bienias
%A S. Choi
%A I. Martin
%A O. Firstenberg
%A M. D. Lukin
%A H. P. Büchler
%A Alexey V. Gorshkov
%X We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wavefunction resembles that of a diatomic molecule in which the two polaritons are separated by a finite "bond length." These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.
%B Physical Review Letters
%V 115
%P 123601
%8 2015/09/16
%G eng
%U http://arxiv.org/abs/1505.03859v1
%N 12
%! Phys. Rev. Lett.
%R 10.1103/PhysRevLett.115.123601