title: Two-stage melting in systems of strongly interacting Rydberg atoms.
abstract: We analyze the ground state properties of a one-dimensional cold atomic system in a lattice, where Rydberg excitations are created by an external laser drive. In the classical limit, the ground state is characterized by a complete devil's staircase for the commensurate solid structures of Rydberg excitations. Using perturbation theory and a mapping onto an effective low-energy Hamiltonian, we find a transition of these commensurate solids into a floating solid with algebraic correlations. For stronger quantum fluctuations the floating solid eventually melts within a second quantum phase transition and the ground state becomes paramagnetic.
authors.affiliation: Institute of Theoretical Physics III, Universität Stuttgart, 70550 Stuttgart, Germany. hweimer@itp3.uni-stuttgart.de
authors.forename: Hendrik
authors.initials: H
authors.lastname: Weimer
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Büchler