21 research outputs found
Weak force detection with superposed coherent states
We investigate the utility of non classical states of simple harmonic
oscillators, particularly a superposition of coherent states, for sensitive
force detection. We find that like squeezed states a superposition of coherent
states allows displacement measurements at the Heisenberg limit. Entangling
many superpositions of coherent states offers a significant advantage over a
single mode superposition states with the same mean photon number.Comment: 6 pages, no figures: New section added on entangled resources.
Changes to discussions and conclusio
Various correlations in a Heisenberg XXZ spin chain both in thermal equilibrium and under the intrinsic decoherence
In this paper we discuss various correlations measured by the concurrence
(C), classical correlation (CC), quantum discord (QD), and geometric measure of
discord (GMD) in a two-qubit Heisenberg XXZ spin chain in the presence of
external magnetic field and Dzyaloshinskii-Moriya (DM) anisotropic
antisymmetric interaction. Based on the analytically derived expressions for
the correlations for the cases of thermal equilibrium and the inclusion of
intrinsic decoherence, we discuss and compare the effects of various system
parameters on the correlations in different cases. The results show that the
anisotropy Jz is considerably crucial for the correlations in thermal
equilibrium at zero temperature limit but ineffective under the consideration
of the intrinsic decoherence, and these quantities decrease as temperature T
rises on the whole. Besides, J turned out to be constructive, but B be
detrimental in the manipulation and control of various quantities both in
thermal equilibrium and under the intrinsic decoherence which can be avoided by
tuning other system parameters, while D is constructive in thermal equilibrium,
but destructive in the case of intrinsic decoherence in general. In addition,
for the initial state , all
the correlations except the CC, exhibit a damping oscillation to a stable value
larger than zero following the time, while for the initial state , all the correlations monotonously
decrease, but CC still remains maximum. Moreover, there is not a definite
ordering of these quantities in thermal equilibrium, whereas there is a
descending order of the CC, C, GMD and QD under the intrinsic decoherence with
a nonnull B when the initial state is .Comment: 8 pages, 7 figure
Degradation in PV encapsulant strength of attachment: An interlaboratory study towards a climate-specific test
Reduced strength of attachment of the encapsulant resulting from the outdoor environment, including ultraviolet (UV) radiation, may decrease photovoltaic (PV) module lifetime by enabling widespread corrosion of internal components. To date, few studies exist showing how the adhesion of PV components varies with environmental stress. We have conducted an interlaboratory experiment to provide an understanding that will be used to develop climatic specific module tests. Factors examined in the study included the UV light source (lamp type), temperature, and humidity to be proposed for use in accelerated aging tests. A poly (ethylene-co-vinyl acetate) (EVA) formulation often used in veteran PV installations was studied using a compressive shear test - to quantify the strength of attachment at the EVA/glass interface. Replicate laminated glass/polymer/glass coupon specimens were weathered at 12 institutions using a variety of indoor chambers or field aging. Shear strength, s hear strain, and toughness were measured using a mechanical load-frame for the compressive shear test, with subsequent optical imaging and electron microscopy of the separated surfaces