00489nas a2200145 4500008003900000245009700039210006900136260000800205300001100213490000800224100002500232700001400257700001500271856005700286 2019 d00aFrustrated quantum spin systems in small triangular lattices studied with a numerical method0 aFrustrated quantum spin systems in small triangular lattices stu cOct a1551190 v1001 aCastells-Graells, D.1 aYuste, A.1 aSanpera, A uhttps://link.aps.org/doi/10.1103/PhysRevB.100.15511900559nas a2200157 4500008003900000245007300039210006900112260001200181300001100193490000700204100001600211700002300227700001800250700001500268856011800283 2015 d00aThermometry precision in strongly correlated ultracold lattice gases0 aThermometry precision in strongly correlated ultracold lattice g c05/2015 a0550200 v171 aMehboudi, M1 aMoreno-Cardoner, M1 aChiara, De, G1 aSanpera, A uhttps://grupsderecerca.uab.cat/giq/publications/thermometry-precision-strongly-correlated-ultracold-lattice-gases01352nas 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-chains01302nas a2200193 4500008003900000022001400039245006700053210006700120260001100187490000800198520069100206100002000897700001300917700001700930700001600947700001800963700001500981856011200996 2012 d a1079-711400aQuantum Memory Assisted Probing of Dynamical Spin Correlations0 aQuantum Memory Assisted Probing of Dynamical Spin Correlations c2/20120 v1083 aWe propose a method to probe time-dependent correlations of nontrivial observables in many-body ultracold lattice gases. The scheme uses a quantum nondemolition matter-light interface, first to map the observable of interest on the many-body system into the light and then to store coherently such information into an external system acting as a quantum memory. Correlations of the observable at two (or more) instances of time are retrieved with a single final measurement that includes the readout of the quantum memory. Such a method brings to reach the study of dynamics of many-body systems in and out of equilibrium by means of quantum memories in the field of quantum simulators.1 aRomero-Isart, O1 aRizzi, M1 aMuschik, C A1 aPolzik, E S1 aLewenstein, M1 aSanpera, A uhttps://grupsderecerca.uab.cat/giq/publications/quantum-memory-assisted-probing-dynamical-spin-correlations01227nas 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/e05445101249nas 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/1007.040301297nas a2200157 4500008003900000022001400039245005700053210005700110260001200167300001400179490000800193520085100201100001401052700001501066856005801081 2011 d a1573-735700aDetection of Entanglement in Ultracold Lattice Gases0 aDetection of Entanglement in Ultracold Lattice Gases c12/2011 a292 - 3050 v1653 aProbing non trivial magnetic ordering in quantum magnets realized with ultracold lattice gases demands detection methods with some spatial resolution built on it. Here we demonstrate that the Faraday matter-light interface provides an experimentally feasible tool to distinguish indubitably different quantum phases of a given many-body system in a non-demolishing way. We illustrate our approach by focussing on the Heisenberg chain for spin-1 bosons in the presence of a SU(2) symmetry breaking field. We explain how using the light signal obtained via homodyne detection one can reconstruct the phase diagram of the model. Further we show that the very same technique that provides a direct experimentally measurable signal of different order parameters can be extended to detect also the presence of multipartite entanglement in such systems.1 aChiara, G1 aSanpera, A ulink.springer.com/article/10.1007%2Fs10909-011-0403-801162nas a2200145 4500008003900000245005400039210005400093300001100147490000700158520074100165100002400906700002000930700001500950856005100965 2011 d00aProbing magnetic order in ultracold lattice gases0 aProbing magnetic order in ultracold lattice gases a0216040 v833 aA forthcoming challenge in ultracold lattice gases is the simulation of quantum magnetism. That involves both the preparation of the lattice atomic gas in the desired spin state and the probing of the state. Here we demonstrate how a probing scheme based on atom-light interfaces gives access to the order parameters of nontrivial quantum magnetic phases, allowing us to characterize univocally strongly correlated magnetic systems produced in ultracold gases. This method, which is also nondemolishing, yields spatially resolved spin correlations and can be applied to bosons or fermions. As a proof of principle, we apply this method to detect the complete phase diagram displayed by a chain of (rotationally invariant) spin-1 bosons.1 aDe Chiara, Gabriele1 aRomero-Isart, O1 aSanpera, A uhttp://pra.aps.org/abstract/PRA/v83/i2/e02160401090nas a2200157 4500008003900000245008000039210006900119260004000188300001100228490000700239520058100246100001700827700001500844700001800859856005500877 2010 d00aCreating p-wave superfluids and topological excitations in optical lattices0 aCreating pwave superfluids and topological excitations in optica bAmerican Physical SocietycMar/2010 a0316070 v813 aWe propose to realize a p-wave superfluid using bosons mixed with a single species of fermions in a deep optical lattice. We analyze with a self-consistent method its excitation spectrum in presence of a vortex, and we point out the range of interaction strengths in which the zero-energy mode with topological character exists on a finite optical lattice. Lattice effects are strongest close to fermionic half filling: here the linearity of the low-lying spectrum is lost, and a new class of extended zero-energy modes with checkerboard structure and d-wave symmetry appears.1 aMassignan, P1 aSanpera, A1 aLewenstein, M uhttp://link.aps.org/doi/10.1103/PhysRevA.81.03160700562nas a2200157 4500008004100000022001400041245013200055210006900187490000700256100001500263700001500278700002400293700001800317700001800335856005100353 2004 eng d a0031-900700aAtomic Fermi-Bose Mixtures in Inhomogeneous and Random Lattices: From Fermi Glass to Quantum Spin Glass and Quantum Percolation0 aAtomic FermiBose Mixtures in Inhomogeneous and Random Lattices F0 v931 aSanpera, A1 aKantian, A1 aSanchez-Palencia, L1 aZakrzewski, J1 aLewenstein, M uhttp://prl.aps.org/abstract/PRL/v93/i4/e04040100513nas a2200181 4500008004100000022001400041245005600055210005500111490000700166100001800173700001500191700001800206700001300224700001400237700001300251700001500264856005200279 2004 eng d a0031-900700aCoherence Properties of Guided-Atom Interferometers0 aCoherence Properties of GuidedAtom Interferometers0 v921 aKreutzmann, H1 aPoulsen, U1 aLewenstein, M1 aDumke, R1 aErtmer, W1 aBirkl, G1 aSanpera, A uhttp://prl.aps.org/abstract/PRL/v92/i16/e16320100518nas a2200181 4500008004100000022001400041245005800055210005800113490000700171100001400178700001400192700001300206700001300219700001800232700002000250700001500270856005100285 2002 eng d a1050-294700aDetection of entanglement with few local measurements0 aDetection of entanglement with few local measurements0 v661 aGühne, O1 aHyllus, P1 aBruß, D1 aEkert, A1 aLewenstein, M1 aMacchiavello, C1 aSanpera, A uhttp://pra.aps.org/abstract/PRA/v66/i6/e06230500411nas a2200145 4500008004100000022001400041245004700055210004600102490000700148100001300155700001300168700001800181700001500199856005100214 2001 eng d a0031-900700aClassification of Mixed Three-Qubit States0 aClassification of Mixed ThreeQubit States0 v871 aAcín, A1 aBruß, D1 aLewenstein, M1 aSanpera, A uhttp://prl.aps.org/abstract/PRL/v87/i4/e04040101228nas a2200253 4500008004100000022001400041245007300055210006900128300001200197490000800209520052100217100001600738700001300754700001700767700001500784700001600799700001500815700001400830700001400844700001900858700001500877700001800892856006400910 2001 eng d a0036-807500aFeynman's path-integral approach for intense-laser-atom interactions0 aFeynmans pathintegral approach for intenselaseratom interactions a902–50 v2923 aAtoms interacting with intense laser fields can emit electrons and photons of very high energies. An intuitive and quantitative explanation of these highly nonlinear processes can be found in terms of a generalization of classical Newtonian particle trajectories, the so-called quantum orbits. Very few quantum orbits are necessary to reproduce the experimental results. These orbits are clearly identified, thus opening the way for an efficient control as well as previously unknown applications of these processes.1 aSalieres, P1 aCarre, B1 aLe Deroff, L1 aGrasbon, F1 aPaulus, G G1 aWalther, H1 aKopold, R1 aBecker, W1 aMilosevic, D B1 aSanpera, A1 aLewenstein, M uhttp://www.sciencemag.org/cgi/content/abstract/292/5518/902