Browsing by Subject "Quantum correlations"
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Item Open Access Bounding the Set of Finite Dimensional Quantum Correlations(American Physical Society, 2015) Navascués, M.; Vértesi, T.We describe a simple method to derive high performance semidefinite programing relaxations for optimizations over complex and real operator algebras in finite dimensional Hilbert spaces. The method is very flexible, easy to program, and allows the user to assess the behavior of finite dimensional quantum systems in a number of interesting setups. We use this method to bound the strength of quantum nonlocality in Bell scenarios where the dimension of the parties is bounded from above. We derive new results in quantum communication complexity and prove the soundness of the prepare-and-measure dimension witnesses introduced in Gallego et al., Phys. Rev. Lett. 105, 230501 (2010). Finally, we propose a new dimension witness that can distinguish between classical, real, and complex two-level systems. © 2015 American Physical Society. © 2015 American Physical Society.Item Open Access Quantum correlated light pulses from sequential superradiance of a condensate(2009) Taşgin, M.E.; Oktel, M. Ö.; You L.; MüstecaplIoǧlu Ö.E.We discover an inherent mechanism for entanglement swap associated with sequential superradiance from an atomic Bose-Einstein condensate. Based on careful examinations with both analytical and numerical approaches, we conclude that as a result of the swap mechanism, Einstein-Podolsky-Rosen-type quantum correlations can be detected among the scattered light pulses. © 2009 The American Physical Society.Item Open Access Quantum correlations among superradiant bose-einstein condensate atoms(M A I K Nauka - Interperiodica, 2010) Taşgin, M. E.; Öztop, B.; Oktel, M. Ö.; Müstecapliog̃lu, Ö. E.Quantum correlations among atoms in superradiant Bose-Einstein condensates are discussed. It is shown that atoms in the superradiant atomic condensate can exhibit continuous variable quantum entanglement analogous to Einstein-Podolsky-Rosen (EPR)-type quantum correlations. Comparison to quantum entanglement in the Dicke model in thermal equilibrium is provided.Item Open Access Quantum correlations of spin-1 atoms in an optical lattice(Institute of Physics Publishing, 2009) Öztop, B.; Oktel, M. Ö.; Müstecaplioǧlu, Ö. E.In this work, we investigate the system of cold spin-1 atoms in a one dimensional optical lattice in relation with squeezing and entanglement. By using the corresponding Bose-Hubbard Hamiltonian, both superfluid and Mott-insulator phases are studied by using numerical methods in the mean-field approximation. To observe the presence of entanglement, we used a squeezing measure as a criterion for quantum correlations. We further investigate the two interaction regimes, namely ferromagnetic and antiferromagnetic in the case of zero and nonzero but very small angle between the counterpropagating laser beams that form the optical lattice. States in the superfluid phase are calculated analytically by using the perturbation theory.Item Open Access Quantum entanglement of spin-1 bosons with coupled ground states in optical lattices(IOP Institute of Physics Publishing, 2009) Öztop, B.; Oktel, M. Ö.; Müstecapliolu, Ö. E.; You, L.We examine particle entanglement, characterized by pseudo-spin squeezing, of spin-1 bosonic atoms with coupled ground states in a one-dimensional optical lattice. Both the superfluid and Mott-insulator phases are investigated separately for ferromagnetic and antiferromagnetic interactions. Mode entanglement is also discussed in the Mott-insulating phase. The role of a small but nonzero angle between the polarization vectors of counter-propagating lasers forming the optical lattice on quantum correlations is investigated as well.Item Open Access Quantum entanglement via superradiance of a Bose-Einstein condensate(Institute of Physics Publishing, 2010) Taşgın, M. E.; Oktel, M. Ö.; You, L.; Müstecaploǧlu, Ö. E.We adopt the coherence and built-in swap mechanism in sequential superradiance as a tool for obtaining continuous-variable (electric/magnetic fields) quantum entanglement of two counter-propagating pulses emitted from the two end-fire modes. In the first-sequence, end-fire modes are entangled with the side modes. In the second sequence, this entanglement is swapped to in between the two opposite end-fire modes. Additionally, we also examine the photon number correlations. No quantum correlations is observed in this variable.