Saturation of atomic transitions using sub-wavelength diameter tapered optical fibers in rubidium vapor

We experimentally investigate ultralow-power saturation of the rubidium D2 transitions using a tapered optical fiber (TOF) suspended in a warm Rb vapor. A direct comparison of power-dependent absorption measurements for the TOF system with those obtained in a standard free-space vapor cell system highlights the differences in saturation behavior for the two systems. The effects of hyperfine pumping in the TOF system are found to be minimized due to the short atomic transit times through the highly confined evanescent optical mode guided by the TOF. The TOF system data is well-fit by a relatively simple empirical absorption model that indicates nanoWatt-level saturation powers.Comment: 6 pages, 6 figure

Cyclical Quantum Memory for Photonic Qubits

We have performed a proof-of-principle experiment in which qubits encoded in the polarization states of single-photons from a parametric down-conversion source were coherently stored and read-out from a quantum memory device. The memory device utilized a simple free-space storage loop, providing a cyclical read-out that could be synchronized with the cycle time of a quantum computer. The coherence of the photonic qubits was maintained during switching operations by using a high-speed polarizing Sagnac interferometer switch.Comment: 4 pages, 5 figure

Parametric performance of circumferentially grooved heat pipes with homogeneous and graded-porosity slab wicks at cryogenic temperatures

A recently developed, potentially high-performance nonarterial wick has been extensively tested. This slab wick has an axially varying porosity which can be tailored to match the local stress imposed on the wick. The purpose of the tests was to establish the usefulness of the graded-porosity slab wick at cryogenic temperatures between 110 K and 260 K, with methane and ethane as working fluids. For comparison, a homogeneous (i.e., uniform porosity) slab wick was also tested. The tests included: (1) maximum heat pipe performance as a function of fluid inventory, (2) maximum performance as a function of operating temperature, (3) maximum performance as a function of evaporator elevation, and (4) influence of slab wick orientation on performance. The experimental data was compared with theoretical predictions obtained with the computer program GRADE

Apalachee During the Brisih Occupation

According to Prof. F. H. Hodder, in the introduction to his reprint of Pittman’s work entitled “The Present State of the European Settlements on the Mississippi,” there are but few available biographical data pertaining to Pittman. Hodder there presents such information as he was able to collect. Apparently Pittman must have accompanied the first British detachment occupying Florida, he states that he “resided four years as an engineer in those parts” and it is known that he left towards the close of 1768. Apparently during 1767 he was occupied in making surveys in different parts of West Florida, as records survive indicating his departure from. Pensacola for Apalachee on June 16, 1767. However the four reports here considered, submitted by Lieut. Pittman to General Haldimand bear no date. They are preserved among the Haldimand papers in the Public Archives of Canada, where they are calendared as Series B (Haldimand) Vol. 17, pp. 313-325. They are respectively numbered 313, 316, 319 and 322.

Bounds on the Probability of Success of Postselected Non-linear Sign Shifts Implemented with Linear Optics

The fundamental gates of linear optics quantum computation are realized by using single photons sources, linear optics and photon counters. Success of these gates is conditioned on the pattern of photons detected without using feedback. Here it is shown that the maximum probability of success of these gates is typically strictly less than 1. For the one-mode non-linear sign shift, the probability of success is bounded by 1/2. For the conditional sign shift of two modes, this probability is bounded by 3/4. These bounds are still substantially larger than the highest probabilities shown to be achievable so far, which are 1/4 and 2/27, respectively.Comment: 6 page

Does Need for Cognition Moderate the Relationship Between Eyewitness Age and Perceived Credibility?

The relationship between age and perceived credibility was examined, particularly whether or not middle-aged witnesses were perceived as more credible than older eyewitnesses. Additionally, I was interested in whether or not the relationship between age and credibility was moderated by need for cognition. Participants read a trial transcript about a child pedestrian-car accident wherein a defendant was charged with manslaughter. The sole eyewitness, either a 49 or 79 year-old male, testified that the child hit his head on a rock upon stepping off the curb before being struck by the defendant’s vehicle. Transcripts included direct and cross-examination with half accompanied by the eyewitness’ photo. Participants rated witness credibility on nine dimensions including competence, honesty, and suggestibility, then rendered a verdict. Participants completed the Need for Cognition Scale and a questionnaire measuring attitudes towards punishment. There was a significant three-way interaction between age, information type, and need for cognition on perceived credibility ratings. Perceived credibility ratings were positively correlated with judgments of guilt. Results are discussed in terms of their implications within the criminal justice system