21,237 research outputs found
Effects of uncertainties and errors on Lyapunov control
Lyapunov control (open-loop) is often confronted with uncertainties and
errors in practical applications. In this paper, we analyze the robustness of
Lyapunov control against the uncertainties and errors in quantum control
systems. The analysis is carried out through examinations of uncertainties and
errors, calculations of the control fidelity under influences of the
certainties and errors, as well as discussions on the caused effects. Two
examples, a closed control system and an open control system, are presented to
illustrate the general formulism.Comment: 4 pages, 5 figure
Berry's phase with quantized field driving: effects of inter-subsystem coupling
The effect of inter-subsystem couplings on the Berry phase of a composite
system as well as that of its subsystem is investigated in this paper. We
analyze two coupled spin- particles with one driven by a quantized
field as an example, the pure state geometric phase of the composite system as
well as the mixed state geometric phase for the subsystem is calculated and
discussed.Comment: 4 pages, 1 figur
Entropy and specific heat for open systems in steady states
The fundamental assumption of statistical mechanics is that the system is
equally likely in any of the accessible microstates. Based on this assumption,
the Boltzmann distribution is derived and the full theory of statistical
thermodynamics can be built. In this paper, we show that the Boltzmann
distribution in general can not describe the steady state of open system. Based
on the effective Hamiltonian approach, we calculate the specific heat, the free
energy and the entropy for an open system in steady states. Examples are
illustrated and discussed.Comment: 4 pages, 7 figure
Atom-molecule conversion with particle losses
Based on the mean-field approximation and the phase space analysis, we study
the dynamics of an atom-molecule conversion system subject to particle loss.
Starting from the many-body dynamics described by a master equation, an
effective nonlinear Schr\"odinger equation is introduced. The classical phase
space is then specified and classified by fixed points. The boundary, which
separate different dynamical regimes have been calculated and discussed. The
effect of particle loss on the conversion efficiency and the self-trapping is
explored.Comment: 6 pages, 5 figure
Surface-wave-enabled darkfield aperture for background suppression during weak signal detection
Sensitive optical signal detection can often be confounded by the presence of a significant background, and, as such, predetection background suppression is substantively important for weak signal detection. In this paper, we present a novel optical structure design, termed surface-wave-enabled darkfield aperture (SWEDA), which can be directly incorporated onto optical sensors to accomplish predetection background suppression. This SWEDA structure consists of a central hole and a set of groove pattern that channels incident light to the central hole via surface plasmon wave and surface-scattered wave coupling. We show that the surface wave component can mutually cancel the direct transmission component, resulting in near-zero net transmission under uniform normal incidence illumination. Here, we report the implementation of two SWEDA structures. The first structure, circular-groove-based SWEDA, is able to provide polarization-independent suppression of uniform illumination with a suppression factor of 1230. The second structure, linear-groove-based SWEDA, is able to provide a suppression factor of 5080 for transverse-magnetic wave and can serve as a highly compact (5.5 micrometer length) polarization sensor (the measured transmission ratio of two orthogonal polarizations is 6100). Because the exact destructive interference balance is highly delicate and can be easily disrupted by the nonuniformity of the localized light field or light field deviation from normal incidence, the SWEDA can therefore be used to suppress a bright background and allow for sensitive darkfield sensing and imaging (observed image contrast enhancement of 27 dB for the first SWEDA)
How consumers’ need for variety and social consumption influences festival patronage and spending
This paper investigates the influence of motivational goals such as variety seeking and social consumption on consumers’ patronage and spending at craft beer festivals. In doing so, we develop and test a number of hypotheses by examining information collected via means of a survey questionnaire proposed in 2017 to visitors of a large beer festival in the UK. Findings of our analysis unveil how cognitive engagement affects individuals’ behavior with regard to responding to and financially engage with beer festivals. Results also identify cognitive engagement as an important mediator of the effects related to variety-seeking and social consumption. From a managerial perspective, findings reveal important attributes affecting consumers’ drivers towards craft beers, contributing to understand which dimension of consumer engagement influence their behaviors. Overall, the study provides fresh empirical evidence in terms of identifying and recognizing consumers’ behaviors with regard to defining future trends in the craft beer secto
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