01377nas a2200181 4500008003900000022001400039245006900053210006800122260000800190490000700198520083300205100002601038700002201064700001901086700001801105700002401123856004801147 2017 d a2469-995000aMagnetic phases of spin-1 lattice gases with random interactions0 aMagnetic phases of spin1 lattice gases with random interactions cjun0 v953 aA spin-1 atomic gas in an optical lattice, in the unit-filling Mott insulator (MI) phase and in the presence of disordered spin-dependent interaction, is considered. In this regime, at zero temperature, the system is well described by a disordered rotationally invariant spin-1 bilinear-biquadratic model. We study, via the density matrix renormalization group algorithm, a bounded disorder model such that the spin interactions can be locally either ferromagnetic or antiferromagnetic. Random interactions induce the appearance of a disordered ferromagnetic phase characterized by a nonvanishing value of the spin glass order parameter across the boundary between a ferromagnetic phase and a dimer phase exhibiting random singlet order. We also study the distribution of the block entanglement entropy in the different regions.1 aMcAlpine, Kenneth, D.1 aPaganelli, Simone1 aCiuchi, Sergio1 aSanpera, Anna1 aDe Chiara, Gabriele uhttps://grupsderecerca.uab.cat/giq/node/84901659nas 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, André1 aPaganelli, Simone1 aRieger, Heiko1 aMorigi, Giovanna uhttp://prl.aps.org/abstract/PRL/v110/i7/e07530400585nas a2200157 4500008003900000245007900039210006900118300001100187490000700198100002100205700001900226700002200245700001800267700002100285856012100306 2013 d00aQuantum phases of incommensurate optical lattices due to cavity backaction0 aQuantum phases of incommensurate optical lattices due to cavity a0436180 v881 aHabibian, Hessam1 aWinter, André1 aPaganelli, Simone1 aRieger, Heiko1 aMorigi, Giovanna uhttps://grupsderecerca.uab.cat/giq/publications/quantum-phases-incommensurate-optical-lattices-due-cavity-backaction00542nas a2200169 4500008003900000022001400039245004700053210004700100260001100147490000700158100002200165700002300187700002400210700002400234700002200258856009200280 2013 d a1094-162200aRouting quantum information in spin chains0 aRouting quantum information in spin chains c6/20130 v871 aPaganelli, Simone1 aLorenzo, Salvatore1 aApollaro, Tony, J G1 aPlastina, Francesco1 aGiorgi, Gian Luca uhttps://grupsderecerca.uab.cat/giq/publications/routing-quantum-information-spin-chains01074nas a2200157 4500008003900000022001400039245005600053210005600109300001100165490000700176520061900183100002200802700002200824700001800846856005200864 2012 d a1367-263000aBeyond pure state entanglement for atomic ensembles0 aBeyond pure state entanglement for atomic ensembles a0330340 v143 aWe analyze multipartite entanglement between atomic ensembles within quantum matter–light interfaces. In our proposal, a polarized light beam crosses sequentially several polarized atomic ensembles impinging on each of them at a given angle $\alpha$ i . These angles are crucial parameters for shaping the entanglement since they are directly connected to the appropriate combinations of the collective atomic spins that are squeezed. We exploit such a scheme to go beyond the pure state paradigm proposing realistic experimental settings to address multipartite mixed state entanglement in continuous variables.1 aStasińska, Julia1 aPaganelli, Simone1 aSanpera, Anna uhttp://stacks.iop.org/1367-2630/14/i=3/a=03303400575nas a2200169 4500008004100000245008100041210006900122260004300191300001400234490000700248100002300255700002200278700002000300700001700320700001300337856005500350 2012 eng d00aSpin-driven spatial symmetry breaking of spinor condensates in a double well0 aSpindriven spatial symmetry breaking of spinor condensates in a bAmerican Physical Societyc2012/11/26/ a053626 - 0 v861 aMelé-Messeguer, M1 aPaganelli, Simone1 aJuliá-Díaz, B1 aSanpera, Ann1 aPolls, A uhttp://link.aps.org/doi/10.1103/PhysRevA.86.05362601249nas a2200133 4500008004100000245007300041210006900114520082900183100001801012700002201030700001301052700001501065856003501080 2011 eng d00aA continuous-variable formalism for the Faraday atom-light interface0 acontinuousvariable formalism for the Faraday atomlight interface3 aQuantum interfaces between polarized atomic ensembles and coherent states of light, applied recently to manipulate bipartite and multipartite entanglement, are revisited by means of a continuous-variable formalism. The explicit use of the continuous-variable formalism facilitates significantly the analysis of entanglement between different modes, reducing it to the study of the properties of a final covariance matrix which can be found analytically. Furthermore, it allows to study matter-light interfaces for mixed states, adapting the formalism to the experimental situations in which the initial prepared Gaussian states are, unavoidably, affected by a certain amount of noise. A multipartite scenario, leading to the generation of macroscopic cluster states is presented and analyzed in detail within this formalism.1 aStasińska, J1 aPaganelli, Simone1 aRodó, C1 aSanpera, A uhttp://arxiv.org/abs/1007.040301687nas a2200193 4500008004100000245004100041210004000082300001100122490000700133520113800140653004601278653002001324100001901344700002201363700001701385700001801402700001801420856005501438 2011 eng d00aDisordered spinor Bose-Hubbard model0 aDisordered spinor BoseHubbard model a0136050 v833 aWe study the zero-temperature phase diagram of the disordered spin-1 Bose-Hubbard model in a two-dimensional square lattice. To this aim, we use a mean-field Gutzwiller ansatz and a probabilistic mean-field perturbation theory. The spin interaction induces two different regimes, corresponding to a ferromagnetic and antiferromagnetic order. In the ferromagnetic case, the introduction of disorder reproduces analogous features of the disordered scalar Bose-Hubbard model, consisting in the formation of a Bose glass phase between Mott insulator lobes. In the antiferromagnetic regime, the phase diagram differs more from the scalar case. Disorder in the chemical potential can lead to the disappearance of Mott insulator lobes with an odd-integer filling factor and, for sufficiently strong spin coupling, to Bose glass of singlets between even-filling Mott insulator lobes. Disorder in the spinor coupling parameter results in the appearance of a Bose glass phase only between the n and the n+1 lobes for n odd. Disorder in the scalar Hubbard interaction inhibits Mott insulator regions for occupation larger than a critical value.10aCondensed Matter - Other Condensed Matter10aQuantum Physics1 aŁ{\k a}cki, M1 aPaganelli, Simone1 aAhufinger, V1 aSanpera, Anna1 aZakrzewski, J uhttp://link.aps.org/doi/10.1103/PhysRevA.83.01360500454nas a2200157 4500008003900000245003800039210003700077300000800114490000800122100002200130700002200152700002400174700002200198700001800220856005800238 2011 d00aSpin Effects in Bose-Glass Phases0 aSpin Effects in BoseGlass Phases a2270 v1651 aPaganelli, Simone1 aŁa̧cki, Mateusz1 aAhufinger, Veronica1 aZakrzewski, Jakub1 aSanpera, Anna uhttp://www.springerlink.com/content/10w5036068935773/01672nas a2200169 4500008004100000245011200041210006900153260000900222300001100231490000700242520102900249653002001278100002201298700002201320700002001342856014001362 2010 eng d00aIon-trap simulation of the quantum phase transition in an exactly solvable model of spins coupled to bosons0 aIontrap simulation of the quantum phase transition in an exactly c2010 a0521180 v813 aIt is known that arrays of trapped ions can be used to efficiently simulate a variety of many-body quantum systems. Here we show how it is possible to build a model representing a spin chain interacting with bosons that is exactly solvable. The exact spectrum of the model at zero temperature and the ground-state properties are studied. We show that a quantum phase transition occurs when the coupling between spins and bosons reaches a critical value, which corresponds to a level crossing in the energy spectrum. Once the critical point is reached, the number of bosonic excitations in the ground state, which can be assumed as an order parameter, starts to be different from zero. The population of the bosonic mode is accompanied by a macroscopic magnetization of the spins. This double effect could represent a useful resource for phase transition detection since a measure of the phonon can give information about the phase of the spin system. A finite-temperature phase diagram is also given in the adiabatic regime.10aQuantum Physics1 aGiorgi, Gian Luca1 aPaganelli, Simone1 aGalve, Fernando uhttps://grupsderecerca.uab.cat/giq/publications/ion-trap-simulation-quantum-phase-transition-exactly-solvable-model-spins-coupled-boson01755nas a2200265 4500008004100000245008100041210006900122260001700191300001500208490000700223520094900230653002701179653001601206653002301222653002801245653003001273653002501303653001901328100002201347700001801369700002201387700001801409700001301427856004901440 2009 eng d00aManipulating mesoscopic multipartite entanglement with atom-light interfaces0 aManipulating mesoscopic multipartite entanglement with atomlight bAPSc12/2009 a062304–80 v803 aEntanglementbetween two macroscopic atomic ensembles induced by measurement on anancillary light system has proven to be a powerful methodfor engineering quantum memories and quantum state transfer. Here weinvestigate the feasibility of such methods for generation, manipulation, anddetection of genuine multipartite entanglement (Greenberger-Horne-Zeilinger and clusterlike states) betweenmesoscopic atomic ensembles without the need of individual addressing ofthe samples. Our results extend in a nontrivial way theEinstein-Podolsky-Rosen entanglement between two macroscopic gas samples reported experimentally in[B. Julsgaard, A. Kozhekin, and E. Polzik, Nature (London) 413,400 (2001)]. We find that under realistic conditions, a secondorthogonal light pulse interacting with the atomic samples, can modifyand even reverse the entangling action of the first oneleaving the samples in a separable state. ©2009 The American Physical Society10aatom-photon collisions10aEPR paradox10ameasurement theory10amesoscopic entanglement10amultipartite entanglement10aquantum entanglement10aquantum optics1 aStasińska, Julia1 aRodó, Carles1 aPaganelli, Simone1 aSanpera, Anna1 aBirkl, G uhttp://link.aps.org/abstract/PRA/v80/e06230401119nas a2200157 4500008004100000022001300041245007700054210006900131300001600200490000700216520063600223100002200859700001600881700001600897856004800913 2009 eng d a0015820800aOptimized electron propagation on a quantum chain by a topological phase0 aOptimized electron propagation on a quantum chain by a topologic a1094–11020 v573 aWe study the quantum diffusion of an electron in a quantum chain starting from an initial state localized around a given site. As the wavepacket diffuses, the probability of reconstructing the initial state on another site diminishes drastically with the distance. In order to optimize the state transmission we find that a topological quantum phase can be introduced. The effect of this phase is the reduction of wavepacket spreading together with almost coherent group propagation. In this regime, the electron has a quasi-linear dispersion and high fidelity can be achieved also over large distances in terms of lattice spacing.1 aPaganelli, Simone1 aGiorgi, G L1 aPasquale, F uhttp://doi.wiley.com/10.1002/prop.200900087