High contrast D1_{1} line electromagnetically induced transparency in nanometric-thin rubidium vapor cell

Electromagnetically induced transparency (EIT) on atomic D$_{1}$ line of rubidium is studied using a nanometric-thin cell with atomic vapor column length in the range of L= 400 - 800 nm. It is shown that the reduction of the cell thickness by 4 orders as compared with an ordinary cm-size cell still allows to form an EIT resonance for $L= \lambda$ ($\lambda =794$ nm) with the contrast of up to 40%. Remarkable distinctions of EIT formation in nanometric-thin and ordinary cells are demonstrated. Despite the Dicke effect of strong spectral narrowing and increase of the absorption for $L=$ $\lambda /2$, EIT resonance is observed both in the absorption and the fluorescence spectra for relatively low intensity of the coupling laser. Well resolved splitting of the EIT resonance in moderate magnetic field for $L=$ $\lambda$ can be used for magnetometry with nanometric spatial resolution. The presented theoretical model well describes the observed results.Comment: Submitted to Applied Physics B: Lasers and Optics, 9 pages, 10 figure

Evanescent light-matter Interactions in Atomic Cladding Wave Guides

Alkali vapors, and in particular rubidium, are being used extensively in several important fields of research such as slow and stored light non-linear optics3 and quantum computation. Additionally, the technology of alkali vapors plays a major role in realizing myriad industrial applications including for example atomic clocks magentometers8 and optical frequency stabilization. Lately, there is a growing effort towards miniaturizing traditional centimeter-size alkali vapor cells. Owing to the significant reduction in device dimensions, light matter interactions are greatly enhanced, enabling new functionalities due to the low power threshold needed for non-linear interactions. Here, taking advantage of the mature Complimentary Metal-Oxide-Semiconductor (CMOS) compatible platform of silicon photonics, we construct an efficient and flexible platform for tailored light vapor interactions on a chip. Specifically, we demonstrate light matter interactions in an atomic cladding wave guide (ACWG), consisting of CMOS compatible silicon nitride nano wave-guide core with a Rubidium (Rb) vapor cladding. We observe the highly efficient interaction of the electromagnetic guided mode with the thermal Rb cladding. The nature of such interactions is explained by a model which predicts the transmission spectrum of the system taking into account Doppler and transit time broadening. We show, that due to the high confinement of the optical mode (with a mode area of 0.3{\lambda}2), the Rb absorption saturates at powers in the nW regime.Comment: 10 Pages 4 Figures. 1 Supplementar

Atomic spectroscopy on a chip

Abstract: We demonstrate the ability to generate extremely large rubidium densities in uncoated hollow-core photonic band-gap fibers using lightinduced atomic desorption. Once the fiber is exposed to Rb vapor for 1-2 weeks, and this atomic source is removed, the fiber yields large desorbable densities for an extended period of time. We show that optical depths greater than e -1200 can be created within seconds. Our observed Rb densities are several orders of magnitude larger than any previously reported to be generated optically, and allow for the demonstration of a relatively easy-touse fiber-based vapor cell capable of producing large optical depths without the need for thermal tuning. H. Schmidt and A. Imamoğlu, "Giant Kerr nonlinearities obtained by electromagnetically-induced transparency," Opt. Lett. 21, 1936Lett. 21, -1938Lett. 21, (199

On the possibility of phase transitions with the formation of SiO2 peroxide forms in the earth mantle and their effect on mantle convection

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Based on the hypothesis advanced by S. P. Gabuda that the SiO2 molecule could undergo a transition from the linear form to the isomeric form with a ring-shaped (bent) structure, an idea is proposed that when the mantle substance melts, a phase transition of the bent SiO2 form into the linear SiO2 form can occur in the lower mantle. This phase transition might be of great importance for the lower-mantle convection processes and also for the rise of mantle plumes carrying both heat energy, and broad range of platinum group and rare elements to the Earth surface. © 2016, Pleiades Publishing, Ltd

On the possibility of phase transitions with the formation of SiO2 peroxide forms in the earth mantle and their effect on mantle convection

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Based on the hypothesis advanced by S. P. Gabuda that the SiO2 molecule could undergo a transition from the linear form to the isomeric form with a ring-shaped (bent) structure, an idea is proposed that when the mantle substance melts, a phase transition of the bent SiO2 form into the linear SiO2 form can occur in the lower mantle. This phase transition might be of great importance for the lower-mantle convection processes and also for the rise of mantle plumes carrying both heat energy, and broad range of platinum group and rare elements to the Earth surface. © 2016, Pleiades Publishing, Ltd

The Metalloprotease of Listeria monocytogenes Is Regulated by pH▿

Listeria monocytogenes is an intracytosolic bacterial pathogen. Among the factors contributing to escape from vacuoles are a phosphatidylcholine phospholipase C (PC-PLC) and a metalloprotease (Mpl). Both enzymes are translocated across the bacterial membrane as inactive proproteins, whose propeptides serve in part to maintain them in association with the bacterium. We have shown that PC-PLC maturation is regulated by Mpl and pH and that Mpl maturation occurs by autocatalysis. In this study, we tested the hypothesis that Mpl activity is pH regulated. To synchronize the effect of pH on bacteria, the cytosolic pH of infected cells was manipulated immediately after radiolabeling de novo-synthesized bacterial proteins. Immunoprecipitation of secreted Mpl from host cell lysates revealed the presence of the propeptide and catalytic domain in samples treated at pH 6.5 but not at pH 7.3. The zymogen was present in small amounts under all conditions. Since proteases often remain associated with their respective propeptide following autocatalysis, we aimed at determining whether pH regulates autocatalysis or secretion of the processed enzyme. For this purpose, we used an Mpl construct that contains a Flag tag at the N terminus of its catalytic domain and antibodies that can distinguish N-terminal and non-N-terminal Flag. By fluorescence microscopy, we observed the Mpl zymogen associated with the bacterium at physiological pH but not following acidification. Mature Mpl was not detected in association with the bacterium at either pH. Using purified proteins, we determined that processing of the PC-PLC propeptide by mature Mpl is also pH sensitive. These results indicate that pH regulates the activity of Mpl on itself and on PC-PLC