A Compact Source for Quantum Image Processing with Four-wave Mixing in Rubidium-85

We have built a compact light source for bright squeezed twin-beams at 795\,nm based on four-wave-mixing in atomic $^{85}$Rb vapor. With a total optical power of 400\,mW derived from a free running diode laser and a tapered amplifier to pump the four-wave-mixing process, we achieve 2.1\,dB intensity difference squeezing of the twin beams below the standard quantum limit, without accounting for losses. Squeezed twin beams generated by the type of source presented here could be used as reference for the precise calibration of photodetectors. Transferring the quantum correlations from the light to atoms in order to generate correlated atom beams is another interesting prospect. In this work we investigate the dispersion that is generated by the employed four-wave-mixing process with respect to bandwidth and dependence on probe detuning. We are currently using this squeezed light source to test the transfer of spatial information and quantum correlations through media of anomalous dispersion.Comment: 6 pages, 4 figure

Ethnic Identity and the Perception of Facial Profile Aesthetics: A Preliminary Study

In a multicultural society, the orthodontist is often faced with the challenge of interpreting an individual’s aesthetic preferences, which depending on the individual might differ from Eurocentric standards. Psychological researchers have recognized that ethnicity is dynamic, and better defined as a perception of self, influenced by social interaction and cultural involvement. Ethnic identity was investigated using three broad ethnic groups (Caucasian-American, African-American and Asian-American) with an established Multicultural Ethnic Identity Measure (Revised [MEIM-R]). Profiles for males and females of each group were constructed using published soft tissue data. Each profile was modified from subnasale to soft tissue B-point by displacing the upper and lower lips horizontally in 2mm increments from Ricketts’ E-plane (-4mm, -2mm, 0mm [ideal], +2mm and +4mm). Six sets of profiles and demographic questions were presented through an online survey to groups of adult males and females (n = 380), stratified by ethnicity and supplied by Survey Monkey Audience® (surveymonkey.com). MEIM-R scores for the Caucasian-American groups were lower than the African- or Asian-American groups. With the exception of the African-American groups, significant profile preferences were observed. A moderate correlation (p\u3c0.01) was observed between the MEIM-R score and a more retrusive profile preference for the Caucasian-American female ethnic group. All other groups showed weak, non-significant correlations between profile preference and ethnic identity. With the exception of the Caucasian-American female group, it appeared that ethnic identity did not contribute significantly to profile preference

Sequestering CO2 by Mineralization into Useful Nesquehonite-Based Products

The work described here was supported financially by GORD, the Gulf Organisation for Research and Development, based in Doha, Qatar. It forms part of the “Green Concrete” project at the University of Aberdeen.Peer reviewedPublisher PD

Quantum mutual information of an entangled state propagating through a fast-light medium

Although it is widely accepted that classical information cannot travel faster than the speed of light in vacuum, the behavior of quantum correlations and quantum information propagating through actively-pumped fast-light media has not been studied in detail. To investigate this behavior, we send one half of an entangled state of light through a gain-assisted fast-light medium and detect the remaining quantum correlations. We show that the quantum correlations can be advanced by a small fraction of the correlation time while the entanglement is preserved even in the presence of noise added by phase-insensitive gain. Additionally, although we observe an advance of the peak of the quantum mutual information between the modes, we find that the degradation of the mutual information due to the added noise appears to prevent an advancement of the leading edge. In contrast, we show that both the leading and trailing edges of the mutual information in a slow-light system can be significantly delayed

Demonstration of images with negative group velocities

We report the experimental demonstration of the superluminal propagation of multi-spatial-mode images via four-wave mixing in hot atomic vapor, in which all spatial sub-regions propagate with negative group velocities. We investigate the spatial mode properties and temporal reshaping of the fast light images, and show large relative pulse peak advancements of up to 64% of the input pulse width. The degree of temporal reshaping is quantified and increases as the relative pulse peak advancement increases. When optimized for image quality or pulse advancement, negative group velocities of up to $v_{g}=-\frac{c}{880}$ and $v_{g}=-\frac{c}{2180}$, respectively, are demonstrated when integrating temporally over the entire image. The present results are applicable to temporal cloaking devices that require strong manipulation of the dispersion relation, where one can envision temporally cloaking various spatial regions of an image for different durations. Additionally, the modes involved in a four-wave mixing process similar to the present experiment have been shown to exhibit quantum correlations and entanglement. The results presented here provide insight into how to tailor experimental tests of the behavior of these quantum correlations and entanglement in the superluminal regime.Comment: 9 pages, 4 figure

Thermodynamics of Portland Cement Clinkering

Acknowledgements The authors would like to thank Gulf Organization for Research and Development (GORD, Qatar) for funding.Postprin