%0 Journal Article
%J New Journal of Physics
%D 2012
%T Beyond pure state entanglement for atomic ensembles
%A Julia Stasińska
%A Paganelli, Simone
%A Sanpera, Anna
%X We 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.
%B New Journal of Physics
%V 14
%P 033034
%U http://stacks.iop.org/1367-2630/14/i=3/a=033034
%R 10.1088/1367-2630/14/3/033034
%0 Journal Article
%J J. Math. Phys.
%D 2012
%T Convergence of expansions in Schrödinger and Dirac eigenfunctions, with an application to the R-matrix theory
%A Julia Stasińska
%B J. Math. Phys.
%V 53
%P 022101
%U http://arxiv.org/pdf/0912.2909v3
%R 10.1063/1.3679763
%0 Journal Article
%J New J. Phys.
%D 2012
%T Glass to superfluid transition in dirty bosons on a lattice
%A Julia Stasińska
%A Massignan, Pietro
%A Bishop, Michael
%A Wehr, Jan
%A Sanpera, Anna
%A Lewenstein, Maciej
%X We investigate the interplay between disorder and interactions in a Bose gas on a lattice in presence of randomly localized impurities. We compare the performance of two theoretical methods, the simple version of multi-orbital Hartree-Fock and the common Gross-Pitaevskii approach, showing how the former gives a very good approximation to the ground state in the limit of weak interactions, where the superfluid fraction is small. We further prove rigorously that for this class of disorder the fractal dimension of the ground state d* tends to the physical dimension in the thermodynamic limit. This allows us to introduce a quantity, the fractional occupation, which gives insightful information on the crossover from a Lifshits to a Bose glass. Finally, we compare temperature and interaction effects, highlighting similarities and intrinsic differences.
%B New J. Phys.
%V 14
%P 043043
%U http://arxiv.org/abs/1111.3494
%R 10.1088/1367-2630/14/4/043043
%0 Journal Article
%J Phys. Rev. Lett.
%D 2011
%T Bell Inequalities with No Quantum Violation and Unextendable Product Bases
%A Remigiusz Augusiak
%A Julia Stasińska
%A Hadley, Christopher
%A Korbicz, Jarosław K.
%A Lewenstein, Maciej
%A Acín, Antonio
%X The strength of classical correlations is subject to certain constraints, commonly known as Bell inequalities. Violation of these inequalities is the manifestation of nonlocality—displayed, in particular, by quantum mechanics, meaning that quantum mechanics can outperform classical physics at tasks associated with such Bell inequalities. Interestingly, however, there exist situations in which this is not the case. We associate an intriguing class of bound entangled states, constructed from unextendable product bases with a wide family of tasks, for which (i) quantum correlations do not outperform the classical ones but (ii) there exist supraquantum nonsignaling correlations that do provide an advantage.
%B Phys. Rev. Lett.
%I American Physical Society
%V 107
%P 070401
%8 Aug
%R 10.1103/PhysRevLett.107.070401
%0 Journal Article
%J Physical Review A (Atomic, Molecular, and Optical Physics)
%D 2009
%T Manipulating mesoscopic multipartite entanglement with atom-light interfaces
%A Julia Stasińska
%A Rodó, Carles
%A Paganelli, Simone
%A Sanpera, Anna
%A Birkl, G.
%K atom-photon collisions
%K EPR paradox
%K measurement theory
%K mesoscopic entanglement
%K multipartite entanglement
%K quantum entanglement
%K quantum optics
%X Entanglementbetween 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 Society
%B Physical Review A (Atomic, Molecular, and Optical Physics)
%I APS
%V 80
%P 062304–8
%8 12/2009
%G eng
%U http://link.aps.org/abstract/PRA/v80/e062304
%0 Journal Article
%J New Journal of Physics
%D 2009
%T Positive maps, majorization, entropic inequalities and detection of entanglement
%A Remigiusz Augusiak
%A Julia Stasińska
%B New Journal of Physics
%V 11
%P 053018
%8 05/2009
%U http://stacks.iop.org/1367-2630/11/i=5/a=053018
%R 10.1088/1367-2630/11/5/053018