Novel Cascaded Ultra Bright Pulsed Source of Polarization Entangled Photons

A new ultra bright pulsed source of polarization entangled photons has been realized using type-II phase matching in spontaneous parametric down conversion process in two cascaded crystals. The optical axes of the crystals are aligned in such a way that the extraordinarily (ordinarily) polarized cone from one crystal overlaps with the ordinarily (extraordinarily) polarized cone from the second crystal. This spatial overlapping removes the association between the polarization and the output angle of the photons that exist in a single type-II down conversion process. Hence, entanglement of photons originating from any point on the output cones is possible if a suitable optical delay line is used. This delay line is particularly simple and easy to implement.Comment: 8 pages 8 figure

Bright source of spectrally uncorrelated polarization-entangled photons with nearly single-mode emission

We present results of a bright polarization-entangled photon source operating at 1552 nm via type-II collinear degenerate spontaneous parametric down-conversion in a periodically poled potassium titanyl phosphate crystal. We report a conservative inferred pair generation rate of 123,000 pairs/s/mW into collection modes. Minimization of spectral and spatial entanglement was achieved by group velocity matching the pump, signal and idler modes and through properly focusing the pump beam. By utilizing a pair of calcite beam displacers, we are able to overlap photons from adjacent down-conversion processes to obtain polarization-entanglement visibility of 94.7 +/- 1.1% with accidentals subtracted.Comment: 4 pages, 7 color figures. Revised manuscript includes the following changes: corrected pair generation rate from 44,000/s/mW pump to 123,000/s/mW pump; replaced Fig. 1b to enhance clarity; minor alterations to the title, abstract and introduction; grammatical correction

Reliability of the beamsplitter based Bell-state measurement

A linear 50/50 beamsplitter, together with a coincidence measurement, has been widely used in quantum optical experiments, such as teleportation, dense coding, etc., for interferometrically distinguishing, measuring, or projecting onto one of the four two-photon polarization Bell-states $|\psi^{(-)}>$. In this paper, we demonstrate that the coincidence measurement at the output of a beamsplitter cannot be used as an absolute identifier of the input state $|\psi^{(-)}>$ nor as an indication that the input photons have projected to the $|\psi^{(-)}>$ state.Comment: 4 pages, two-colum

Bright filter-free source of indistinguishable photon pairs

We demonstrate a high-brightness source of pairs of indistinguishable photons based on a type-II phase-matched doubly-resonant optical parametric oscillator operated far below threshold. The cavity-enhanced down-conversion output of a PPKTP crystal is coupled into two single-mode fibers with a mode coupling efficiency of 58%. The high degree of indistinguishability between the photons of a pair is demonstrated by a Hong-Ou-Mandel interference visibility of higher than 90% without any filtering at an instantaneous coincidence rate of 450 000 pairs/s per mW of pump power per nm of down-conversion bandwidth. For the degenerate spectral mode with a linewidth of 7 MHz at 795 nm a rate of 70 pairs/(s mW MHz) is estimated, increasing the spectral brightness for indistinguishable photons by two orders of magnitude compared to similar previous sources.Comment: 7 pages, 3 figure

Bell State Preparation using Pulsed Non-Degenerate Two-Photon Entanglement

We report a novel Bell state preparation experiment. High-purity Bell states are prepared by using femtosecond pulse pumped \emph{nondegenerate} collinear spontaneous parametric down-conversion. The use of femtosecond pump pulse {\em does not} result in reduction of quantum interference visibility in our scheme in which post-selection of amplitudes and other traditional mechanisms, such as, using thin nonlinear crystals or narrow-band spectral filters are not used. Another distinct feature of this scheme is that the pump, the signal, and the idler wavelengths are all distinguishable, which is very useful for quantum communications.Comment: 4 pages, submitted to PR

Generating multimedia presentations: from plain text to screenplay

In many Natural Language Generation (NLG) applications, the output is limited to plain text – i.e., a string of words with punctuation and paragraph breaks, but no indications for layout, or pictures, or dialogue. In several projects, we have begun to explore NLG applications in which these extra media are brought into play. This paper gives an informal account of what we have learned. For coherence, we focus on the domain of patient information leaflets, and follow an example in which the same content is expressed first in plain text, then in formatted text, then in text with pictures, and finally in a dialogue script that can be performed by two animated agents. We show how the same meaning can be mapped to realisation patterns in different media, and how the expanded options for expressing meaning are related to the perceived style and tone of the presentation. Throughout, we stress that the extra media are not simple added to plain text, but integrated with it: thus the use of formatting, or pictures, or dialogue, may require radical rewording of the text itself

Violation of Bell's Inequality with Photons from Independent Sources

We report a violation of Bell's inequality using one photon from a parametric down-conversion source and a second photon from an attenuated laser beam. The two photons were entangled at a beam splitter using the post-selection technique of Shih and Alley [Phys. Rev. Lett. 61, 2921 (1988)]. A quantum interference pattern with a visibility of 91% was obtained using the photons from these independent sources, as compared with a visibility of 99.4% using two photons from a central parametric down-conversion source.Comment: 4 pages, 5 figures; minor change

Nonclassical 2-photon interference with separate intrinsically narrowband fibre sources

In this paper, we demonstrate a source of photon pairs based on four-wave-mixing in photonic crystal fibres. Careful engineering of the phase matching conditions in the fibres enables us to create photon pairs at 597 nm and 860 nm in an intrinsically factorable state showing no spectral correlations. This allows for heralding one photon in a pure state and hence renders narrow band filtering obsolete. The source is narrow band, bright and achieves an overall detection efficiency of up to 21% per photon. For the first time, a Hong-Ou-Mandel interference with unfiltered photons from separate fibre sources is presented.Comment: 10 pages, 6 figure

Outcomes from a single-intervention trial to improve interprofessional practice behaviors at a student-led free clinic

Background Interprofessional collaboration (IPC) is the practice of two or more healthcare professionals working together and learning from one another to improve health outcomes. IPC is important for quality training, typically improving individual and group level outcomes. Students value the opportunity for leadership and teamwork development when IPC is offered in their curriculum. The Indiana University Student Outreach Clinic (IUSOC) is a student run clinic that provides free primary care services to underserved residents residing in Indianapolis, Indiana. The IUSOC partner leaders identified a need to enhance knowledge about partner roles, scope of practice, and professional training with the hopes of improving quality of care through IPC and utilization of clinic resources. Methods A cluster randomized design consisted of education session days and control days. Participants had an equal selection probability. Student partners from ten different disciplines were involved. Two survey instruments were used for data collection: 1) The Interprofessional Socialization and Valuing Scale and 2) The Professional Consciousness Raising Questionnaire. The former measured the attitudes and beliefs that underlie interprofessional socialization, while the latter assessed pre/post student knowledge of the roles and responsibilities of each partner. Results The control arm of the study was composed of 167 student participants and the intervention arm had 170 participants. Participants in the intervention arm had greater scores for “ability to work with others”, “value in working with others”, and “comfort in working with others.” The intervention arm also had significantly increased odds of correctly identifying the roles responsibilities of the nursing, law, dental, and global health disciplines. Conclusions Results of this study demonstrate that administering a short interprofessional education exercise to healthcare professional students leads to improved IPC through increased interprofessional knowledge about other professions and change in beliefs and values toward the value of interprofessional collaboration among healthcare professionals

Heuristics for Broader Assessment of Effectiveness and Usability in Technology-Mediated Technical Communication

Purpose: To offer additional tools for the assessment of effectiveness and usability in technology-mediated communication based in established heuristics. Method: An interdisciplinary group of researchers at Rensselaer Polytechnic Institute selected five disparate examples of technology-mediated communication, formally evaluated each using contemporary heuristics, and then engaged in an iterative design process to arrive at an expanded toolkit for in depth analyses. Results: A set of heuristics and operationalized metrics for the deeper analysis of a broader scope of contemporary technology-mediated communication. Conclusions: The continual evolution of communication, including the emergence of new, interactive media, provides a challenging opportunity to identify effective approaches and techniques. There are benefits to a renewed focus on relationships between people and between people and information, and we offer additional criteria and metrics to supplement established means of heuristic analysis