Finite-well potential in the 3D nonlinear Schroedinger equation: Application to Bose-Einstein condensation

Using variational and numerical solutions we show that stationary negative-energy localized (normalizable) bound states can appear in the three-dimensional nonlinear Schr\"odinger equation with a finite square-well potential for a range of nonlinearity parameters. Below a critical attractive nonlinearity, the system becomes unstable and experiences collapse. Above a limiting repulsive nonlinearity, the system becomes highly repulsive and cannot be bound. The system also allows nonnormalizable states of infinite norm at positive energies in the continuum. The normalizable negative-energy bound states could be created in BECs and studied in the laboratory with present knowhow.Comment: 8 pages, 12 figure

Loss of superfluidity in a Bose-Einstein condensate via forced resonant oscillations

We predict the loss of superfluidity in a Bose-Einstein condensate in an axially symmetric harmonic trap alone during resonant collective oscillations via a classical dynamical transition. The forced resonant oscillation can be initiated by (a) a periodic modulation of the atomic scattering length with a frequency that equals twice the radial trapping frequency or multiples thereof, or by (b) a periodic modulation of the radial trapping potential with a frequency that equals the radial trapping frequency or multiples thereof. Suggestion for future experiment is made.Comment: 12 Latex Pages, 12 eps figures, Accepted in Physics Letters

Josephson oscillation of a superfluid Fermi gas

Using the complete numerical solution of a time-dependent three-dimensional mean-field model we study the Josephson oscillation of a superfluid Fermi gas (SFG) at zero temperature formed in a combined axially-symmetric harmonic plus one-dimensional periodic optical-lattice (OL) potentials after displacing the harmonic trap along the axial OL axis. We study the dependence of Josephson frequency on the strength of the OL potential. The Josephson frequency decreases with increasing strength as found in the experiment of Cataliotti et al. [Science 293 (2001) 843] for a Bose-Einstein condensate and of the experiment of Pezze et al. [Phys. Rev. Lett. 93 (2004) 120401] for an ideal Fermi gas. We demonstrate a breakdown of Josephson oscillation in the SFG for a large displacement of the harmonic trap. These features of Josephson oscillation of a SFG can be tested experimentally.Comment: 7 pages, 10 figure

Entanglement and Teleportation in Bipartite System

We present a mathematical formulation of old teleportation protocol (original teleportation protocol introduced by Bennett et.al.) for mixed states and study in detail the role of mixedness of the two qubit quantum channel in a teleportation protocol. We show that maximally entangled mixed state described by the density matrix of rank-4 will be useful as a two qubit teleportation channel to teleport a single qubit mixed state when the teleportation channel parameter p1 greater than 0.5. Also we discuss the case when p1 less than equal to 0.5.Comment: 16 pages and 5 figures. Accepted in IJQ

Josephson oscillation and induced collapse in an attractive Bose-Einstein condensate

Using the axially-symmetric time-dependent Gross-Pitaevskii equation we study the Josephson oscillation of an attractive Bose-Einstein condensate (BEC) in a one-dimensional periodic optical-lattice potential. We find that the Josephson frequency is virtually independent of the number of atoms in the BEC and of the inter-atomic interaction (attractive or repulsive). We study the dependence of Josephson frequency on the laser wave length and the strength of the optical-lattice potential. For a fixed laser wave length (795 nm), the Josephson frequency decreases with increasing strength as found in the experiment of Cataliotti {\it et al.} [Science {\bf 293}, 843 (2001)]. For a fixed strength, the Josephson frequency remains essentially unchanged for a reasonable variation of laser wave length around 800 nm. However, for a fixed strength, the Josephson oscillation is disrupted with the increase of laser wave length beyond 2000 nm leading to a collapse of a sufficiently attractive BEC. These features of Josephson oscillation can be tested experimentally with present set ups.Comment: 7 pages, 12 ps and eps figures, Physical Review

Market-based Approaches to Environmental Management: A Review of Lessons from Payment for Environmental Services in Asia

Market-based approaches to environmental management, such as payment for environmental services (PES), have attracted unprecedented attention during the past decade. PES policies, in particular, have emerged to realign private and social benefits such as internalizing ecological externalities and diversifying sources of conservation funding as well as making conservation an attractive land-use paradigm. In this paper, we review several case studies from Asia on payment for environmental services to understand how landowners decide to participate in PES schemes. The analysis demonstrates the significance of four major elements facilitating the adoption and implementation of PES schemes: property rights and tenure security, transaction costs, household and community characteristics, communications, and the availability of PES-related information. PES schemes should target win-win options through intervention in these areas, aimed at maintaining the provision of ecological services and improving the conditions for local inhabitants

Estimation of Entanglement Negativity of a Two-Qubit Quantum System With Two Measurements

Numerous work had been done to quantify the entanglement of a two-qubit quantum state, but it can be seen that previous works were based on joint measurements on two copies or more than two copies of a quantum state under consideration. In this work, we show that a single copy and two measurements are enough to estimate the entanglement quantifier like entanglement negativity and concurrence. To achieve our aim, we establish a relationship between the entanglement negativity and the minimum eigenvalue of structural physical approximation of partial transpose of an arbitrary two-qubit state. The derived relation make possible to estimate entanglement negativity experimentally by Hong-Ou-Mandel interferometry with only two detectors. Also, we derive the upper bound of the concurrence of an arbitrary two-qubit state and have shown that the upper bound can be realized in experiment. We will further show that the concurrence of (i) an arbitrary pure two-qubit states and (ii) a particular class of mixed states, namely, rank-2 quasi-distillable mixed states, can be exactly estimated with two measurements.Comment: 6 pages, 2 figures, Published versio

Sparse Sensing with Semi-Coprime Arrays

A semi-coprime array (SCA) interleaves two undersampled uniform linear arrays (ULAs) and a $Q$ element standard ULA. The undersampling factors of the first two arrays are $QM$ and $QN$ respectively where $M$ and $N$ are coprime. The resulting non-uniform linear array is highly sparse. Taking the minimum of the absolute values of the conventional beampatterns of the three arrays results in a beampattern free of grating lobes. The SCA offers more savings in the number of sensors than other popular sparse arrays like coprime arrays, nested arrays, and minimum redundant arrays. Also, the SCA exhibits better side lobe patterns than other sparse arrays. An example of direction of arrival estimation with the SCA illustrates SCA's promising potential in reducing number of sensors, decreasing system cost and complexity in various signal sensing and processing applications

Interactions and Correlations of Particulate Inclusions in a Columnar Phase

We calculate the elastic field mediated interaction between macroscopic particles in a columnar hexagonal phase. The interaction is found to be long-ranged and non-central, with both attractive and repulsive parts. We show how the interaction modifies the particle correlations and the column fluctuations. We also calculate the interaction of particles with the topological defects of the columnar phase. The particle-defect interaction reduces the mobility of the defects.Comment: RevTeX4 8 pages, 4 eps figures, submitted to Euro. Phys. J.