Optical realization of the two-site Bose-Hubbard model in waveguide lattices

A classical realization of the two-site Bose-Hubbard Hamiltonian, based on light transport in engineered optical waveguide lattices, is theoretically proposed. The optical lattice enables a direct visualization of the Bose-Hubbard dynamics in Fock space.Comment: to be published, J Phys. B (Fast Track Communication

Evaluating Satisfaction in the River Recreation Experience in Big Bend National Park.

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Bloch oscillations of Bose-Einstein condensates: Quantum counterpart of dynamical instability

We study the Bloch dynamics of a quasi one-dimensional Bose-Einstein condensate of cold atoms in a tilted optical lattice modeled by a Hamiltonian of Bose-Hubbard type: The corresponding mean-field system described by a discrete nonlinear Schr\"odinger equation can show a dynamical (or modulation) instability due to chaotic dynamics and equipartition over the quasimomentum modes. It is shown, that these phenomena are related to a depletion of the Floquet-Bogoliubov states and a decoherence of the condensate in the many-particle description. Three different types of dynamics are distinguished: (i) decaying oscillations in the region of dynamical instability, and (ii) persisting Bloch oscillations or (iii) periodic decay and revivals in the region of stability.Comment: 12 pages, 14 figure

Quantum-jump vs stochastic Schrödinger dynamics for Gaussian states with quadratic Hamiltonians and linear Lindbladians

The dynamics of Gaussian states for open quantum systems described by Lindblad equations can be solved analytically for systems with quadratic Hamiltonians and linear Lindbladians, showing the familiar phenomena of dissipation and decoherence. It is well known that the Lindblad dynamics can be expressed as an ensemble average over stochastic pure-state dynamics, which can be interpreted as individual experimental implementations, where the form of the stochastic dynamics depends on the measurement setup. Here we consider quantum-jump and stochastic Schrödinger dynamics for initially Gaussian states. While both unravellings converge to the same Lindblad dynamics when averaged, the individual dynamics can differ qualitatively. For the stochastic Schrödinger equation, Gaussian states remain Gaussian during the evolution, with stochastic differential equations governing the evolution of the phase-space centre and a deterministic evolution of the covariance matrix. In contrast to this, individual pure-state dynamics arising from the quantum-jump evolution do not remain Gaussian in general. Applying results developed in the non-Hermitian context for Hagedorn wavepackets, we formulate a method to generate quantum-jump trajectories that is described entirely in terms of the evolution of an underlying Gaussian state. To illustrate the behaviours of the different unravellings in comparison to the Lindblad dynamics, we consider two examples in detail, which can be largely treated analytically, a harmonic oscillator subject to position measurement and a damped harmonic oscillator. In both cases, we highlight the differences as well as the similarities of the stochastic Schrödinger and the quantum-jump dynamics

A Comparison of Residential and Visitor Attitudes Toward Experiential Impacts, Environmental Conditions and Management Strategies on the Delaware Inland Bays

This paper compares different attitudes toward experiential impacts on boating, environmental conditions, and proposed management strategies held by permanent residents, seasonal residents and seasonal visitors to the Delaware Inland Bays. The study found variation in opinions held by each group indicating the tourism manager should collect information from all groups before developing policy. Additionally, the manager should understand the varying impacts on boater satisfaction depending upon conditions

Control of unstable macroscopic oscillations in the dynamics of three coupled Bose condensates

We study the dynamical stability of the macroscopic quantum oscillations characterizing a system of three coupled Bose-Einstein condensates arranged into an open-chain geometry. The boson interaction, the hopping amplitude and the central-well relative depth are regarded as adjustable parameters. After deriving the stability diagrams of the system, we identify three mechanisms to realize the transition from an unstable to stable behavior and analyze specific configurations that, by suitably tuning the model parameters, give rise to macroscopic effects which are expected to be accessible to experimental observation. Also, we pinpoint a system regime that realizes a Josephson-junction-like effect. In this regime the system configuration do not depend on the model interaction parameters, and the population oscillation amplitude is related to the condensate-phase difference. This fact makes possible estimating the latter quantity, since the measure of the oscillating amplitudes is experimentally accessible.Comment: 25 pages, 12 figure

Public Response to Park and Recreation Funding and Cost-saving Strategies: The Role of Organizational Trust and Committment

Historically, public park and recreation services have been funded through general funds and appropriations, with minimal amounts derived from non-tax revenue sources. The fiscal conservative movement, however, has spawned an expansion of nontax revenues and cost saving strategies. Th is study examines the level of citizen support for a variety of funding and cost-saving strategies for park and recreation agencies in a metropolitan region, and the factors related to citizens’ opinions about such strategies. Data were collected through a mail survey of adult residents of the Harrisburg, Pennsylvania region. A total of 578 questionnaires were completed. Results showed that funding strategies involving external contributions such as donations and corporate sponsorships were most strongly supported by the local citizenry. Respondents were least supportive of park services privatization and the use of park entrance fees. Regression analysis was used to test the relationships between citizen socio-demographic characteristics, park use patterns, organizational trust and commitment, and level of support for the various strategies. Organizational trust, commitment, and citizen characteristics were signifi cantly related to a number of funding strategies. While prior research has examined the role of trust and commitment in the implementation of enterprise funding strategies (e.g. user fees), our data indicates that trust and commitment were more salient for general tax support than for other, more transactional funding strategies, such as user fees and corporate sponsorships. Respondents who perceived that their local park agencies were socially competent and who were more committed to the agency were also more likely to support taxes and less likely to support park privatization. These results affirm that a trusting and committed citizenry is a key ingredient in preventing the erosion of tax-based support and the subsequent privatization of park and recreation services. Park and recreation administrators who wish to expand their funding beyond existing tax support should take actions to foster trust and commitment across their multiple constituent groups. Agencies that currently enjoy a high level of constituent trust and commitment should be cautious when privatizing park services, lest they compromise existing levels of trust and commitment