Quantum critical behavior in strongly interacting Rydberg gases

We study the appearance of correlated many-body phenomena in an
ensemble of atoms driven resonantly into a strongly interacting
Rydberg state. The ground state of the Hamiltonian describing the
driven system exhibits a second order quantum phase transition. We
derive the critical theory for the quantum phase transition and show
that it describes the properties of the driven Rydberg system in the
saturated regime. We find that the suppression of Rydberg excitations
known as blockade phenomena exhibits an algebraic scaling law with a
universal exponent.