A first experimental test of de Broglie-Bohm theory against standard quantum mechanics

De Broglie - Bohm (dBB) theory is a deterministic theory, built for reproducing almost all Quantum Mechanics (QM) predictions, where position plays the role of a hidden variable. It was recently shown that different coincidence patterns are predicted by QM and dBB when a double slit experiment is realised under specific conditions and, therefore, an experiment can test the two theories. In this letter we present the first realisation of such a double slit experiment by using correlated photons produced in type I Parametric Down Conversion. Our results confirm QM contradicting dBB predictions

Observational Constraints on the Model Parameters of a Class of Emergent Universe

A class of Emergent Universe (EU) model is studied in the light of recent observational data. Significant constraints on model parameters are obtained from the observational data. Density parameter for a class of model is evaluated. Some of the models are in favour of the recent observations. Some models have been found which are not interesting yielding unrealistic present day value of the density parameter.Comment: Uses mn2e class file, 5 pages, 9 figures. (submitted to MNRAS

Bohmian trajectories for photons

The first examples of Bohmian trajectories for photons have been worked out for simple situations, using the Kemmer-Duffin-Harishchandra formalism.Comment: 7 pages, Latex, Comments about time-like properties of Bohmian velocities added. Revised version accepted for publication in Physics Letters

Photon Statistics of a Single Atom Laser

We consider a laser model consisting of a single four-level or three-level atom, an optical cavity, and an incoherent pump. Results for photon statistics for varying pump levels are obtained using a quantum trajectory algorithm. In particular, we calculate the mean photon number, Fano factor (which is the variance over the mean). We examine that the behavior of the single-atom device as β, the fraction of spontaneous emission into the lasing mode, is varied. Typical values considered for β are 0.01\u3cβ\u3c1.0. We find that for large enough β, lasing action, with properties similar to those predicted by semiclassical theories that factorize atom-field correlations and use a small-noise approximation, can occur. Squeezing can occur as β is increased. There is no evidence of a sharp phase transition from weakly excited thermal light to coherent light at a particular pump power. This is consistent with work on many-atom lasers with β values in the range considered here. As β is increased, the output goes from quasithermal light to coherent and finally to squeezed light, progressing into a fully quantum-mechanical regime. We also consider the effects of cavity damping and spontaneous emission rates on these results

Estimation of osmotic potential and free amino acids in some mangroves of the Sundarbans, India

Osmotic potential (OP) of root and leaf was measured in 19 species of mangroves collected from the Sundarbans, India. Leaf OP was estimated in 11 taxa from among them, grown in fresh water and compared with that deriving from taxa grown in saline water. Free amino acids were estimated from leaves of 16 mangrove species of the Sundarbans. The osmotic potential in leaves collected from their natural habitat was more negative than that from those grown in fresh water conditions. Seedlings grown without salt provided less negative leaf OPthan those treated with 0.1 mol dm–3 NaCl. The more negative OP was found in more saline soil, which might be related to adaptation to facilitate water uptake from a highly saline and frequently waterlogged anaerobic substratum. Aspartic acid, alanine, proline, tryptophan, tyrosine and phenylalanine are the major free amino acids detected in the leaves. Leucine was recorded only in Avicennia spp., where phenylalanine content was negligible. Proline content was estimated in seven species. The positive linear trend obtained between leaf OP and proline content points to its role as an osmoticum in mangrove leaves. Cysteine, aspartic acid, alanine and phenylalanine were determined in seedlings, while proline could be estimated only in X. mekongensis. Cysteine and proline content in seedling leaves were gradually reduced with increasing soil salinity. Lack of cysteine in mature leaves and its decrease in more saline soil probably indicates salinity as a photorespiration restricting factor. A more or less inverse relationship was found between proline and alanine content both in seedlings and mature plants

Separation of variables for a lattice integrable system and the inverse problem

We investigate the relation between the local variables of a discrete integrable lattice system and the corresponding separation variables, derived from the associated spectral curve. In particular, we have shown how the inverse transformation from the separation variables to the discrete lattice variables may be factorised as a sequence of canonical transformations, following the procedure outlined by Kuznetsov.Comment: 14 pages. submitted for publicatio

Tripartite Entanglement versus Tripartite Nonlocality in Three-Qubit Greenberger-Horne-Zeilinger-Class States

We analyze the relationship between tripartite entanglement and genuine tripartite nonlocality for three-qubit pure states in the Greenberger-Horne-Zeilinger class. We consider a family of states known as the generalized Greenberger-Horne-Zeilinger states and derive an analytical expression relating the three-tangle, which quantifies tripartite entanglement, to the Svetlichny inequality, which is a Bell-type inequality that is violated only when all three qubits are nonlocally correlated. We show that states with three-tangle less than 1/2 do not violate the Svetlichny inequality. On the other hand, a set of states known as the maximal slice states does violate the Svetlichny inequality, and exactly analogous to the two-qubit case, the amount of violation is directly related to the degree of tripartite entanglement.We discuss further interesting properties of the generalized Greenberger-Horne-Zeilinger and maximal slice states

Two-particle interference in standard and Bohmian quantum mechanics

The compatibility of standard and Bohmian quantum mechanics has recently been challenged in the context of two-particle interference, both from a theoretical and an experimental point of view. We analyze different setups proposed and derive corresponding exact forms for Bohmian equations of motion. The equations are then solved numerically, and shown to reproduce standard quantum-mechanical results.Comment: Minor corrections, 2 references added, version to appear in J. Phys.