Spatially resolving two incoherent point sources whose separation is well below the diffraction limit dictated by classical optics has recently been shown possible using techniques that decompose the incoming radiation into orthogonal transverse modes. Such a demultiplexing procedure, however, must be perfectly calibrated to the transverse profile of the incoming light as any misalignment of the modes effectively restores the diffraction limit for small source separations. We study by how much can one mitigate such an effect at the level of measurement which, after being imperfectly demultiplexed due to inevitable misalignment, may still be partially corrected by linearly transforming the relevant dominating transverse modes. We consider two complementary tasks: the estimation of the separation between the two sources and the discrimination between one and two incoherent point sources. We show that, although one cannot fully restore super-resolving powers even when the value of the misalignment is perfectly known its negative impact on the ultimate sensitivity can be significantly reduced. In the case of estimation we analytically determine the exact relation between the minimal resolvable separation as a function of misalignment whereas for discrimination we analytically determine the relation between misalignment and the probability of error, as well as numerically determine how the latter scales in the limit of long interrogation times.

1 ade Almeida, J., O.1 aKołodyński, J.1 aHirche, C.1 aLewenstein, M1 aSkotiniotis, M. uhttps://link.aps.org/doi/10.1103/PhysRevA.103.022406http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevA.103.022406/fulltexthttps://link.aps.org/article/10.1103/PhysRevA.103.02240600724nas a2200181 4500008003900000022001400039245005600053210005600109260001600165490000800181100001800189700001800207700001300225700001300238700001400251700001800265856025900283 2016 d a0031-900700aEntanglement and Coherence in Quantum State Merging0 aEntanglement and Coherence in Quantum State Merging cJan-06-20160 v1161 aStreltsov, A.1 aChitambar, E.1 aRana, S.1 aBera, N.1 aWinter, A1 aLewenstein, M uhttp://link.aps.org/doi/10.1103/PhysRevLett.116.240405http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.116.240405/fulltexthttp://link.aps.org/accepted/10.1103/PhysRevLett.116.240405http://link.aps.org/article/10.1103/PhysRevLett.116.24040501182nas 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/e05445101090nas 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.81.03160700440nas a2200145 4500008003900000245007100039210006900110260001200179300001000191490000700201100001600208700001700224700001800241856003500259 2010 d00aTopological superfluids on a lattice with non-Abelian gauge fields0 aTopological superfluids on a lattice with nonAbelian gauge field c12/2010 a460040 v921 aKubasiak, A1 aMassignan, P1 aLewenstein, M uhttp://arxiv.org/abs/1007.482700562nas 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