Coulomb Bound States of Strongly Interacting Photons
Abstract
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 twobody bound states. Within the continuum, metastable bound states are distinguished in analogy with quasibound 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 wave function 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.
 Publication:

Physical Review Letters
 Pub Date:
 September 2015
 DOI:
 10.1103/PhysRevLett.115.123601
 arXiv:
 arXiv:1505.03859
 Bibcode:
 2015PhRvL.115l3601M
 Keywords:

 42.50.Nn;
 32.80.Ee;
 34.20.Cf;
 42.50.Gy;
 Quantum optical phenomena in absorbing dispersive and conducting media;
 Rydberg states;
 Interatomic potentials and forces;
 Effects of atomic coherence on propagation absorption and amplification of light;
 electromagnetically induced transparency and absorption;
 Quantum Physics;
 Physics  Atomic Physics
 EPrint:
 10 pages, 5 figures