01659nas a2200181 4500008003900000022001400039245006600053210006500119260001100184490000800195520112100203100002101324700001901345700002201364700001801386700002101404856005201425 2013 d a1079-711400aBose-Glass Phases of Ultracold Atoms due to Cavity Backaction0 aBoseGlass Phases of Ultracold Atoms due to Cavity Backaction c2/20130 v1103 aWe determine the quantum ground-state properties of ultracold bosonic atoms interacting with the mode of a high-finesse resonator. The atoms are confined by an external optical lattice, whose period is incommensurate with the cavity mode wavelength, and are driven by a transverse laser, which is resonant with the cavity mode. While for pointlike atoms photon scattering into the cavity is suppressed, for sufficiently strong lasers quantum fluctuations can support the buildup of an intracavity field, which in turn amplifies quantum fluctuations. The dynamics is described by a Bose-Hubbard model where the coefficients due to the cavity field depend on the atomic density at all lattice sites. Quantum Monte Carlo simulations and mean-field calculations show that, for large parameter regions, cavity backaction forces the atoms into clusters with a checkerboard density distribution. Here, the ground state lacks superfluidity and possesses finite compressibility, typical of a Bose glass. This system constitutes a novel setting where quantum fluctuations give rise to effects usually associated with disorder.1 aHabibian, Hessam1 aWinter, AndrĂ©1 aPaganelli, Simone1 aRieger, Heiko1 aMorigi, Giovanna uhttp://prl.aps.org/abstract/PRL/v110/i7/e075304