



@article {1507,
	title = {Coulomb bound states of strongly interacting photons},
	journal = {Physical Review Letters},
	volume = {115},
	year = {2015},
	month = {2015/09/16},
	pages = {123601},
	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 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.
},
	doi = {10.1103/PhysRevLett.115.123601},
	url = {http://arxiv.org/abs/1505.03859v1},
	author = {Mohammad F. Maghrebi and Michael Gullans and P. Bienias and S. Choi and I. Martin and O. Firstenberg and M. D. Lukin and H. P. B{\"u}chler and Alexey V. Gorshkov}
}
@article {1506,
	title = {Scattering resonances and bound states for strongly interacting Rydberg  polaritons
},
	journal = {Physical Review A},
	volume = {90},
	year = {2014},
	month = {2014/11/3},
	abstract = {  We provide a theoretical framework describing slow-light polaritons
interacting via atomic Rydberg states. We use a diagrammatic method to
analytically derive the scattering properties of two polaritons. We identify
parameter regimes where polariton-polariton interactions are repulsive.
Furthermore, in the regime of attractive interactions, we identify multiple
two-polariton bound states, calculate their dispersion, and study the resulting
scattering resonances. Finally, the two-particle scattering properties allow us
to derive the effective low-energy many-body Hamiltonian. This theoretical
platform is applicable to ongoing experiments.
},
	doi = {10.1103/PhysRevA.90.053804},
	url = {http://arxiv.org/abs/1402.7333v1},
	author = {P. Bienias and S. Choi and O. Firstenberg and Mohammad F. Maghrebi and Michael Gullans and M. D. Lukin and Alexey V. Gorshkov and H. P. B{\"u}chler}
}
