Light guided by an optical nanofibre can have a very steep evanescent field gradient extending from the fibre surface. This can be exploited to drive electric quadrupole transitions in nearby quantum emitters. In this paper, we report on the observation of the 5S 1/2 → 4D 3/2 electric quadrupole transition at 516.6 nm (in vacuum) in laser-cooled 87 Rb atoms using only a few µW of laser power propagating through an optical nanofibre embedded in the atom cloud. This work extends the range of applications for optical nanofibres in atomic physics to include more fundamental tests.

Aim: To compare the retentive ability and deformation of Acetal resin with Cobalt-Chromium clasps via Insertion Removal apparatus after subjecting them to stimulate clinical use. Materials and Methods:Materials used for this study are commercially available Cobalt-Chromium alloy namely Wironit, Bego, Germany and Acetal resin namely Biodentaplast, Bredent, Germany. The test samples were divided into two major groups based on the type of materials used in the study. Each major group is further subdivided into two sub groups based on the retentive undercut depths used to engage the clasps. So a total of 20 specimens were prepared, comprising of 5 specimens in each sub group. Then the specimens were tested for retention force and deformation. Results:The results of this study indicate that acetal resin clasps are resistant to deformation and may offer a clinical advantage over the conventional metal clasps. The retentive force of acetal resin clasps did not decrease over the cycling periods. This would be attributed to the resilient nature of acetal resin. Under the conditions of the present study cobalt chromium clasps lost retentive force within 730 cycles of placement and removal and continued to lose retentive force during the remaining test period. Conclusion:This invitro study demonstrated that retentive force of cobalt chromium clasp is superior to that of Acetal resin for removable partial dentures. As acetal resin clasps exhibits greater flexibility and long term retentive resiliency, it can be used for removable partial dentures where aesthetics or periodontal health is a primary concern.A. Meenakshi et al.,

We summarise the discussions at a virtual Community Workshop on Cold Atoms in Space concerning the status of cold atom technologies, the prospective scientific and societal opportunities offered by their deployment in space, and the developments needed before cold atoms could be operated in space. The cold atom technologies discussed include atomic clocks, quantum gravimeters and accelerometers, and atom interferometers. Prospective applications include metrology, geodesy and measurement of terrestrial mass change due to, e.g., climate change, and fundamental science experiments such as tests of the equivalence principle, searches for dark matter, measurements of gravitational waves and tests of quantum mechanics. We review the current status of cold atom technologies and outline the requirements for their space qualification, including the development paths and the corresponding technical milestones, and identifying possible pathfinder missions to pave the way for missions to exploit the full potential of cold atoms in space. Finally, we present a first draft of a possible road-map for achieving these goals, that we propose for discussion by the interested cold atom, Earth Observation, fundamental physics and other prospective scientific user communities, together with the European Space Agency (ESA) and national space and research funding agencies.

We develop a theoretical framework for spin selection in single-frequency two-photon excitation of alkalimetal atoms as a function of polarization of the excitation light. We verify the theory by experimentally probing the 5S 1/2 → 6S 1/2 transition rate in 87 Rb in two configurations: paraxial light excitation of warm vapor and nonparaxial excitation of laser-cooled atoms. The transition rate follows a quadratic dependence on the helicity parameter linked to the excitation light's polarization. For paraxial excitation, the transition rate scales as the squared degree of linear polarization, being zero for circularly polarized light. In contrast, for nonparaxial excitation via an optical nanofiber, the two-photon transition is not completely extinguished by varying the light polarization. Our findings lead to a deeper and more universal understanding of the physics of multiphoton processes in atoms.

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