00483nas a2200145 4500008003900000022001400039245009100053210006900144260001600213300001100229490000700240100002400247700001800271856004800289 2018 d a0034-488500aGenuine quantum correlations in quantum many-body systems: a review of recent progress0 aGenuine quantum correlations in quantum manybody systems a revie cJan-07-2018 a0740020 v811 aDe Chiara, Gabriele1 aSanpera, Anna uhttps://grupsderecerca.uab.cat/giq/node/92101386nas a2200169 4500008003900000022001400039245006800053210006800121260000800189490000700197520087400204100002001078700002301098700002401121700002301145856004801168 2017 d a1367-263000aGlobal and local thermometry schemes in coupled quantum systems0 aGlobal and local thermometry schemes in coupled quantum systems coct0 v193 aWe study the ultimate bounds on the estimation of temperature for an interacting quantum system. We consider two coupled bosonic modes that are assumed to be thermal and using quantum estimation theory establish the role the Hamiltonian parameters play in thermometry. We show that in the case of a conserved particle number the interaction between the modes leads to a decrease in the overall sensitivity to temperature, while interestingly, if particle exchange is allowed with the thermal bath the converse is true. We explain this dichotomy by examining the energy spectra. Finally, we devise experimentally implementable thermometry schemes that rely only on locally accessible information from the total system, showing that almost Heisenberg limited precision can still be achieved, and we address the (im)possibility for multiparameter estimation in the system.1 aCampbell, Steve1 aMehboudi, Mohammad1 aDe Chiara, Gabriele1 aPaternostro, Mauro uhttps://grupsderecerca.uab.cat/giq/node/84201377nas 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/84901005nas a2200157 4500008003900000024002000039245006000059210006000119300001100179490000700190520052600197100002400723700002300747700002200770856005500792 2011 d aarXiv:1105.051300aEntanglement detection in hybrid optomechanical systems0 aEntanglement detection in hybrid optomechanical systems a0523240 v833 aWe study a device formed by a Bose Einstein condensate (BEC) coupled to the field of a cavity with a moving end-mirror and find a working point such that the mirror-light entanglement is reproduced by the BEC-light quantum correlations. This provides an experimentally viable tool for inferring mirror-light entanglement with only a limited set of assumptions. We prove the existence of tripartite entanglement in the hybrid device, persisting up to temperatures of a few milli-Kelvin, and discuss a scheme to detect it. 1 aDe Chiara, Gabriele1 aPaternostro, Mauro1 aPalma, Massimo, G uhttp://link.aps.org/doi/10.1103/PhysRevA.83.05232401162nas 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/e02160400904nas a2200169 4500008003900000024002000039245005900059210005700118260001200175300001100187490000800198520041000206100001900616700002400635700001500659856006000674 2010 d aarxiv:1003.042400aCold-atom induced control of an opto-mechanical device0 aColdatom induced control of an optomechanical device c06/2010 a2436020 v1043 aWe consider a cavity with a vibrating end mirror and coupled to a Bose-Einstein condensate. The cavity field mediates the interplay between mirror and collective oscillations of the atomic density. We study the implications of this dynamics and the possibility of an indirect diagnostic. Our predictions can be observed in a realistic setup that is central to the current quest for mesoscopic quantumness.1 aPaternostro, M1 aDe Chiara, Gabriele1 aPalma, G M u http://link.aps.org/doi/10.1103/PhysRevLett.104.24360201503nas a2200181 4500008003900000024002000039245008500059210006900144260001200213300001100225490000700236520094700243100002401190700002401214700001401238700001401252856005501266 2010 d aarXiv:1001.482700aThe quantum ground state of self-organized atomic crystals in optical resonators0 aquantum ground state of selforganized atomic crystals in optical c04/2010 a0434070 v813 aCold atoms, driven by a laser and simultaneously coupled to the quantum field of an optical resonator, may self-organize in periodic structures. These structures are supported by the optical lattice, which emerges from the laser light they scatter into the cavity mode and form when the laser intensity exceeds a threshold value. We study theoretically the quantum ground state of these structures above the pump threshold of self-organization by mapping the atomic dynamics of the self-organized crystal to a Bose-Hubbard model. We find that the quantum ground state of the self-organized structure can be the one of a Mott insulator, depending on the pump strength of the driving laser. For very large pump strengths, where the intracavity-field intensity is maximum and one would expect a Mott-insulator state, we find intervals of parameters where the phase is compressible. These states could be realized in existing experimental setups.1 aFernández-Vidal, S1 aDe Chiara, Gabriele1 aLarson, J1 aMorigi, G uhttp://link.aps.org/doi/10.1103/PhysRevA.81.04340702221nas a2200181 4500008003900000245007700039210006900116260001200185300001100197490000700208520166400215100002401879700001801903700001401921700001601935700001501951856007301966 2010 d00aSpontaneous nucleation of structural defects in inhomogeneous ion chains0 aSpontaneous nucleation of structural defects in inhomogeneous io c12/2010 a1150030 v123 aStructural defects in ion crystals can be formed during a linear quench of the transverse trapping frequency across the mechanical instability from a linear chain to the zigzag structure. The density of defects after the sweep can be conveniently described by the Kibble-Zurek mechanism. In particular, the number of kinks in the zigzag ordering can be derived from a time-dependent Ginzburg-Landau equation for the order parameter, here the zigzag transverse size, under the assumption that the ions are continuously laser cooled. In a linear Paul trap the transition becomes inhomogeneous, being the charge density larger in the center and more rarefied at the edges. During the linear quench the mechanical instability is first crossed in the center of the chain, and a front, at which the mechanical instability is crossed during the quench, is identified which propagates along the chain from the center to the edges. If the velocity of this front is smaller than the sound velocity, the dynamics becomes adiabatic even in the thermodynamic limit and no defect is produced. Otherwise, the nucleation of kinks is reduced with respect to the case in which the charges are homogeneously distributed, leading to a new scaling of the density of kinks with the quenching rate. The analytical predictions are verified numerically by integrating the Langevin equations of motion of the ions, in presence of a time-dependent transverse confinement. We argue that the non-equilibrium dynamics of an ion chain in a Paul trap constitutes an ideal scenario to test the inhomogeneous extension of the Kibble-Zurek mechanism, which lacks experimental evidence to date. 1 aDe Chiara, Gabriele1 aCampo, Adolfo1 aMorigi, G1 aPlenio, M B1 aRetzker, A uhttp://iopscience.iop.org/1367-2630/12/11/115003?fromSearchPage=true00572nas a2200169 4500008003900000245011700039210006900156260001200225300001100237490000800248100001800256700002400274700001400298700001600312700001500328856005900343 2010 d00aStructural defects in ion crystals by quenching the external potential: the inhomogeneous Kibble-Zurek mechanism0 aStructural defects in ion crystals by quenching the external pot c08/2010 a0757010 v1051 aCampo, Adolfo1 aDe Chiara, Gabriele1 aMorigi, G1 aPlenio, M B1 aRetzker, A uhttp://link.aps.org/doi/10.1103/PhysRevLett.105.075701