01352nas a2200181 4500008003900000022001400039245011200053210006900165260001200234490000700246520069100253100002300944700001400967700001700981700001700998700001501015856014001030 2014 d a1550-235X00aCase study of the uniaxial anisotropic spin-1 bilinear-biquadratic Heisenberg model on a triangular lattice0 aCase study of the uniaxial anisotropic spin1 bilinearbiquadratic c10/20140 v903 aWe study the spin-1 model on a triangular lattice in the presence of a uniaxial anisotropy field using a cluster mean-field (CMF) approach. The interplay among antiferromagnetic exchange, lattice geometry, and anisotropy forces Gutzwiller mean-field approaches to fail in a certain region of the phase diagram. There, the CMF method yields two supersolid phases compatible with those present in the spin−1/2 XXZ model onto which the spin-1 system maps. Between these two supersolid phases, the three-sublattice order is broken and the results of the CMF approach depend heavily on the geometry and size of the cluster. We discuss the possible presence of a spin liquid in this region.1 aMoreno-Cardoner, M1 aPerrin, H1 aPaganelli, S1 aDe Chiara, G1 aSanpera, A uhttps://grupsderecerca.uab.cat/giq/publications/case-study-uniaxial-anisotropic-spin-1-bilinear-biquadratic-heisenberg-model-triangular01365nas a2200169 4500008003900000245006600039210006600105260001200171300001100183490000900194520081200203100002301015700001701038700001701055700001501072856010801087 2014 d00aEntanglement properties of spin models in triangular lattices0 aEntanglement properties of spin models in triangular lattices c10/2014 aP100080 v20143 aThe different quantum phases appearing in strongly correlated systems as well as their transitions are closely related to the entanglement shared between their constituents. In 1D systems, it is well established that the entanglement spectrum is linked to the symmetries that protect the different quantum phases. This relation extends even further at the phase transitions where a direct link associates the entanglement spectrum to the conformal field theory describing the former. For 2D systems much less is known. The lattice geometry becomes a crucial aspect to consider when studying entanglement and phase transitions. Here, we analyze the entanglement properties of triangular spin lattice models by also considering concepts borrowed from quantum information theory such as geometric entanglement.1 aMoreno-Cardoner, M1 aPaganelli, S1 aDe Chiara, G1 aSanpera, A uhttps://grupsderecerca.uab.cat/giq/publications/entanglement-properties-spin-models-triangular-lattices01541nas a2200181 4500008003900000022001400039245008900053210006900142260001100211490000700222520091500229100001801144700001401162700001901176700001701195700001501212856013201227 2014 d a1094-162200aLong-range multipartite entanglement close to a first-order quantum phase transition0 aLongrange multipartite entanglement close to a firstorder quantu c3/20140 v893 aWe provide insight into the quantum correlations structure present in strongly correlated systems beyond the standard framework of bipartite entanglement. To this aim we first exploit rotationally invariant states as a test bed to detect genuine tripartite entanglement beyond the nearest neighbor in spin-1/2 models. Then we construct in a closed analytical form a family of entanglement witnesses which provides a sufficient condition to determine if a state of a many-body system formed by an arbitrary number of spin-1/2 particles possesses genuine tripartite entanglement, independently of the details of the model. We illustrate our method by analyzing in detail the anisotropic XXZ spin chain close to its phase transitions, where we demonstrate the presence of long-range multipartite entanglement near the critical point and the breaking of the symmetries associated with the quantum phase transition.1 aStasińska, J1 aRogers, B1 aPaternostro, M1 aDe Chiara, G1 aSanpera, A uhttps://grupsderecerca.uab.cat/giq/publications/long-range-multipartite-entanglement-close-first-order-quantum-phase-transition00517nas a2200145 4500008003900000022001400039245007200053210006900125260001100194490000700205100001400212700001700226700001500243856011300258 2013 d a1550-235X00aScaling of the entanglement spectrum near quantum phase transitions0 aScaling of the entanglement spectrum near quantum phase transiti c6/20130 v871 aLepori, L1 aDe Chiara, G1 aSanpera, A uhttps://grupsderecerca.uab.cat/giq/publications/scaling-entanglement-spectrum-near-quantum-phase-transitions01182nas a2200169 4500008003900000022001400039245009100053210006900144260001200213490000800225520058100233100001700814700001400831700001800845700001500863856013400878 2012 d a1079-711400aEntanglement Spectrum, Critical Exponents, and Order Parameters in Quantum Spin Chains0 aEntanglement Spectrum Critical Exponents and Order Parameters in c12/20120 v1093 aWe investigate the entanglement spectrum near criticality in finite quantum spin chains. Using finite size scaling we show that when approaching a quantum phase transition, the Schmidt gap, i.e., the difference between the two largest eigenvalues of the reduced density matrix λ1, λ2, signals the critical point and scales with universal critical exponents related to the relevant operators of the corresponding perturbed conformal field theory describing the critical point. Such scaling behavior allows us to identify explicitly the Schmidt gap as a local order parameter.1 aDe Chiara, G1 aLepori, L1 aLewenstein, M1 aSanpera, A uhttps://grupsderecerca.uab.cat/giq/publications/entanglement-spectrum-critical-exponents-and-order-parameters-quantum-spin-chains01227nas a2200157 4500008003900000022001400039245007300053210006900126260001100195490000700206520075500213100001700968700001800985700001501003856005101018 2011 d a1550-235X00aBilinear-biquadratic spin-1 chain undergoing quadratic Zeeman effect0 aBilinearbiquadratic spin1 chain undergoing quadratic Zeeman effe c8/20110 v843 aThe Heisenberg model for spin-1 bosons in one dimension presents many different quantum phases, including the famous topological Haldane phase. Here we study the robustness of such phases in front of a SU(2) symmetry-breaking field as well as the emergence of unique phases. Previous studies have analyzed the effect of such uniaxial anisotropy in some restricted relevant points of the phase diagram. Here we extend those studies and present the complete phase diagram of the spin-1 chain with uniaxial anisotropy. To this aim, we employ the density-matrix renormalization group together with analytical approaches. The complete phase diagram can be realized using ultracold spinor gases in the Mott insulator regime under a quadratic Zeeman effect.1 aDe Chiara, G1 aLewenstein, M1 aSanpera, A uhttp://prb.aps.org/abstract/PRB/v84/i5/e05445101403nas a2200193 4500008003900000022001400039245006400053210006400117260001200181300001000193490000700203520078300210100001200993700001701005700001401022700001201036700001401048856014701062 2011 d a1286-485400aEntangling two distant oscillators with a quantum reservoir0 aEntangling two distant oscillators with a quantum reservoir c09/2011 a600080 v953 aThe generation of entanglement between two oscillators that interact via a common reservoir is theoretically studied. The reservoir is modeled by a one-dimensional harmonic crystal initially in thermal equilibrium. Starting from a separable state, the oscillators can become entangled after a transient time, that is of the order of the thermalization time scale. This behaviour is observed at finite temperature even when the oscillators are at a distance significantly larger than the crystal's interparticle spacing. The underlying physical mechanisms can be explained by the dynamical properties of the collective variables of the two oscillators which may decouple from or be squeezed by the reservoir. Our predictions can be tested with an ion chain in a linear Paul trap.1 aWolf, A1 aDe Chiara, G1 aKajari, E1 aLutz, E1 aMorigi, G uhttp://epljournal.edpsciences.org/index.php?option=com_article&access=standard&Itemid=129&url=/articles/epl/abs/2011/18/epl13816/epl13816.html01272nas a2200181 4500008003900000022001400039245009200053210006900145260001100214490000700225520072800232100001400960700001500974700001700989700001501006700001801021856005101039 2011 d a1094-162200aQuantifying, characterizing, and controlling information flow in ultracold atomic gases0 aQuantifying characterizing and controlling information flow in u c9/20110 v843 aWe study quantum information flow in a model comprised of a trapped impurity qubit immersed in a Bose-Einstein-condensed reservoir. We demonstrate how information flux between the qubit and the condensate can be manipulated by engineering the ultracold reservoir within experimentally realistic limits. We show that this system undergoes a transition from Markovian to non-Markovian dynamics, which can be controlled by changing key parameters such as the condensate scattering length. In this way, one can realize a quantum simulator of both Markovian and non-Markovian open quantum systems, the latter ones being characterized by a reverse flow of information from the background gas (reservoir) to the impurity (system).1 aHaikka, P1 aMcEndoo, S1 aDe Chiara, G1 aPalma, G M1 aManiscalco, S uhttp://pra.aps.org/abstract/PRA/v84/i3/e031602