Schmidt Analysis of Pure-State Entanglement

We examine the application of Schmidt-mode analysis to pure state entanglement. Several examples permitting exact analytic calculation of Schmidt eigenvalues and eigenfunctions are included, as well as evaluation of the associated degree of entanglement.Comment: 5 pages, 3 figures, for C.M. Bowden memoria

A Network of Text, Data and People for the Earth System Sciences

Earth System Science is an outstanding example of a field of research which yields important results especially when conducted in multidisciplinary and global cooperation. The International Polar Year and its expected legacy are used as an example to illustrate this assertion and the financial and intellectual expense invested. It follows that any effort to make more out of the globally distributed – if not fragmented – results and to network the knowledge gained would be valuable indeed. An experimental implementation of such a system, connecting journal articles to datasets, expeditions and researchers involved, is introduced. Some developments necessary to implement comparable and more powerful systems on a global scale are discussed

Quantum Correlations in Two-Boson Wavefunctions

We present the Schmidt decomposition for arbitrary wavefunctions of two indistinguishable bosons, extending the recent studies of entanglement or quantum correlations for two fermion systems [J. Schliemann et al., Phys. Rev. B {\bf 63}, 085311 (2001) and quant-ph/0012094]. We point out that the von Neumann entropy of the reduced single particle density matrix remains to be a good entanglement measure for two identical particles.Comment: in press at Phys. Rev.

Studies of group velocity reduction and pulse regeneration with and without the adiabatic approximation

We present a detailed semiclassical study on the propagation of a pair of optical fields in resonant media with and without adiabatic approximation. In the case of near and on resonance excitation, we show detailed calculation, both analytically and numerically, on the extremely slowly propagating probe pulse and the subsequent regeneration of a pulse via a coupling laser. Further discussions on the adiabatic approximation provide many subtle understandings of the process including the effect on the band width of the regenerated optical field. Indeed, all features of the optical pulse regeneration and most of the intricate details of the process can be obtained with the present treatment without invoke a full field theoretical method. For very far off resonance excitation, we show that the analytical solution is nearly detuning independent, a surprising result that is vigorously tested and compared to numerical calculations with very good agreement.Comment: 13 pages, 15 figures, submitted to Phys. Rev.

Pair creation for bosons in electric and magnetic fields

By solving the quantum field theoretical version of the Klein-Gordon equation numerically, we study the creation process for charged boson-antiboson pairs in static electric and magnetic fields. The fields are perpendicular to each other and spatially localized along the same direction, which permits us to study the crucial impact of the magnetic field\u27s spatial extension on dynamics. If its width is comparable to that of the electric field, we find a magnetically induced Lorentz suppression of the pair-creation process. When the width is increased such that the created bosons can revisit the interaction region, we find a region of exponential self-amplification that can be attributed to a spontaneous emissionlike enhancement. If the width is increased further, this trend is reversed and the magnetic field can even shut off the particle production completely

Demonstration of multi-channel 80 Gbit/s integrated transmitter and receiver for wavelength-division multiplexing passive optical network and fronthauling applications

The performance evaluation of a multi-channel transmitter that employs an arrayed reflective electroabsorption modulator-based photonic integrated circuit and a low-power driver array in conjunction with a multi-channel receiver incorporating a pin photodiode array and integrated arrayed waveguide grating is reported. Due to their small footprint, low power consumption and potential low cost, these devices are attractive solutions for future mobile fronthaul and next generation optical access networks. A BER performance of <10(-9) at 10.3 Gbit/s per channel is achieved over 25 km of standard single mode fibre. The transmitter/receiver combination can achieve an aggregate bit rate of 82.4 Gbit/s when eight channels are active

Electron correlation vs. stabilization: A two-electron model atom in an intense laser pulse

We study numerically stabilization against ionization of a fully correlated two-electron model atom in an intense laser pulse. We concentrate on two frequency regimes: very high frequency, where the photon energy exceeds both, the ionization potential of the outer {\em and} the inner electron, and an intermediate frequency where, from a ``single active electron''-point of view the outer electron is expected to stabilize but the inner one is not. Our results reveal that correlation reduces stabilization when compared to results from single active electron-calculations. However, despite this destabilizing effect of electron correlation we still observe a decreasing ionization probability within a certain intensity domain in the high-frequency case. We compare our results from the fully correlated simulations with those from simpler, approximate models. This is useful for future work on ``real'' more-than-one electron atoms, not yet accessible to numerical {\em ab initio} methods.Comment: 8 pages, 8 figures in an extra ps-file, submitted to Phys. Rev. A, updated references and shortened introductio

Truth Be Told: Evidence of Wheelchair Users’ Accuracy in Reporting Their Height and Weight

Objectives To examine whether wheelchair users’ self-reports of height and weight differed significantly from direct measurements and whether weight category classifications differed substantially when based on self-reported or measured values. Design Single group, cross-sectional analysis. Analyses included paired t tests, chi-square test, analysis of variance, and Bland-Altman agreement analyses. Setting A university-based exercise lab. Participants Community-dwelling wheelchair users (N=125). Interventions Not applicable. Main Outcome Measure Participants’ self-reported and measured height, weight, and body mass index. Results Paired t tests revealed that there were significant differences between wheelchair users’ self-reported and measured values for height (difference of 3.1±7.6cm [1.2±3.0in]), weight (−1.7±6.5kg [−3.6±14.2lb]), and BMI (−1.6±3.3). These discrepancies also led to substantial misclassification into weight categories, with reliance on self-reported BMI underestimating the weight status of 20% of the sample. Conclusions Our findings suggest that similar to the general population, wheelchair users are prone to errors when reporting their height and weight and that these errors may exceed those noted in the general population

Exercise for Everyone: A randomized controlled trial of Project Workout On Wheels in promoting exercise among wheelchair users

This is the author's accepted manuscript. Made available by the permission of the publisher.Objective To compare the effectiveness of two home-based behavioral interventions to promote wheelchair users exercise adoption and maintenance over 12 months. Design Randomized controlled trial, with participants stratified into groups based on disability type (stable, episodic, progressive) and support partner availability. Setting Exercise occurred in participant preferred locations (e.g., home, recreation center), with physiological data collected at the university-based exercise lab. Participants One hundred twenty-eight inactive wheelchair users (64 women) with sufficient upper arm mobility for arm-based exercise enrolled. Participants on average were 45 years old, lived with their impairment for 22 years, with spinal cord injury (46.1%) most commonly reported as causing mobility impairment. Interventions Both groups received home-based exercise interventions. The staff-supported group (n= 69) received intensive exercise support, while the self-guided group (n= 59) received minimal support. Both received exercise information, resistance bands, instructions to self-monitor exercise, regularly-scheduled phone calls, and handwritten cards. Main Outcome Measures The primary outcome derived from weekly self-reported exercise. Secondary outcomes included physical fitness (aerobic/muscular) and predictors of exercise participation. Results The staff-supported group reported significantly greater exercise (~ 16 minutes/week) than the self-guided group over the year (t=10.6, p=0.00), with no significant between group difference in aerobic capacity (t=0.76, p=0.45) and strength (t=1.5, p=0.14). Conclusions Although the staff-supported group reported only moderately more exercise, the difference is potentially clinically significant as they also exercised more frequently. The staff-supported approach holds promise for encouraging exercise among wheelchair users, yet additional support may be necessary to achieve more exercise to meet national recommendations

Schmidt number of pure bi-partite entangled states and methods of its calculation

An entanglement measure for pure-state continuous-variable bi-partite problem, the Schmidt number, is analytically calculated for one simple model of atom-field scattering.Comment: 3 pages, 1 figure; based on the poster presentation reported on the 11th International Conference on Quantum Optics (ICQO'2006, Minsk, May 26 -- 31, 2006), to be published in special issue of Optics and Spectroscop