Engineering Quantum States, Nonlinear Measurements, and Anomalous Diffusion by Imaging

We show that well-separated quantum superposition states, measurements of strongly nonlinear observables, and quantum dynamics driven by anomalous diffusion can all be achieved for single atoms or molecules by imaging spontaneous photons that they emit via resonance florescence. To generate anomalous diffusion we introduce continuous measurements driven by L\'evy processes, and prove a number of results regarding their properties. In particular we present strong evidence that the only stable L\'evy density that can realize a strictly continuous measurement is the Gaussian.Comment: revtex4-1, 17 pages, 7 eps figure

Intercomparison of ILAS-II version 1.4 and version 2 target parameters with MIPAS-Envisat measurements

This paper assesses the mean differences between the two ILAS-II data versions (1.4 and 2) by comparing them with MIPAS measurements made between May and October 2003. For comparison with ILAS-II results, MIPAS data processed at the Institut für Meteorologie und Klimaforschung, Karlsruhe, Germany (IMK) in cooperation with the Instituto de Astrofísica de Andalucía (IAA) in Granada, Spain, were used. The coincidence criteria of ±300 km in space and ±12 h in time for H<sub>2</sub>O, N<sub>2</sub>O, and CH<sub>4</sub> and the coincidence criteria of ±300 km in space and ±6 h in time for ClONO<sub>2</sub>, O<sub>3</sub>, and HNO<sub>3</sub> were used. The ILAS-II data were separated into sunrise (= Northern Hemisphere) and sunset (= Southern Hemisphere). For the sunrise data, a clear improvement from version 1.4 to version 2 was observed for H<sub>2</sub>O, CH<sub>4</sub>, ClONO<sub>2</sub>, and O<sub>3</sub>. In particular, the ILAS-II version 1.4 mixing ratios of H<sub>2</sub>O and CH<sub>4</sub> were unrealistically small, and those of ClONO<sub>2</sub> above altitudes of 30 km unrealistically large. For N<sub>2</sub>O and HNO<sub>3</sub>, there were no large differences between the two versions. Contrary to the Northern Hemisphere, where some exceptional profiles deviated significantly from known climatology, no such outlying profiles were found in the Southern Hemisphere for both versions. Generally, the ILAS-II version 2 data were in better agreement with the MIPAS data than the version 1.4, and are recommended for quantitative analysis in the stratosphere. For H<sub>2</sub>O data in the Southern Hemisphere, further data quality evaluation is necessary

Single-particle-sensitive imaging of freely propagating ultracold atoms

We present a novel imaging system for ultracold quantum gases in expansion. After release from a confining potential, atoms fall through a sheet of resonant excitation laser light and the emitted fluorescence photons are imaged onto an amplified CCD camera using a high numerical aperture optical system. The imaging system reaches an extraordinary dynamic range, not attainable with conventional absorption imaging. We demonstrate single-atom detection for dilute atomic clouds with high efficiency where at the same time dense Bose-Einstein condensates can be imaged without saturation or distortion. The spatial resolution can reach the sampling limit as given by the 8 \mu m pixel size in object space. Pulsed operation of the detector allows for slice images, a first step toward a 3D tomography of the measured object. The scheme can easily be implemented for any atomic species and all optical components are situated outside the vacuum system. As a first application we perform thermometry on rubidium Bose-Einstein condensates created on an atom chip.Comment: 24 pages, 10 figures. v2: as publishe

Metrological characterization of the pulsed Rb clock with optical detection

We report on the implementation and the metrological characterization of a vapor-cell Rb frequency standard working in pulsed regime. The three main parts that compose the clock, physics package, optics and electronics, are described in detail in the paper. The prototype is designed and optimized to detect the clock transition in the optical domain. Specifically, the reference atomic transition, excited with a Ramsey scheme, is detected by observing the interference pattern on a laser absorption signal. \ The metrological analysis includes the observation and characterization of the clock signal and the measurement of frequency stability and drift. In terms of Allan deviation, the measured frequency stability results as low as $1.7\times 10^{-13} \ \tau^{-1/2}$, $\tau$ being the averaging time, and reaches the value of few units of $10^{-15}$ for $\tau=10^{4}$ s, an unprecedent achievement for a vapor cell clock. We discuss in the paper the physical effects leading to this result with particular care to laser and microwave noises transferred to the clock signal. The frequency drift, probably related to the temperature, stays below $10^{-14}$ per day, and no evidence of flicker floor is observed. \ We also mention some possible improvements that in principle would lead to a clock stability below the $10^{-13}$ level at 1 s and to a drift of few units of $10^{-15}$ per day

Narrow 0\u3csup\u3e+\u3c/sup\u3e state in \u3csup\u3e20\u3c/sup\u3eNe and 0\u3csub\u3e6\u3c/sub\u3e\u3csup\u3e+\u3c/sup\u3e and 0\u3csub\u3e7\u3c/sub\u3e\u3csup\u3e+\u3c/sup\u3e rotational bands

A reanalysis of old data removes the (0+,2+) ambiguity for a very narrow state at Ex(20Ne)=11.55 MeV and gives a unique 0+ assignment. Such a 0+ state corresponds well to a predicted state at 11.494 MeV of unusually small reduced widths for decay to both the ground and first excited state of 16O. This new 0+ state is a better 06+ band head for the 8p-4h states at 15.159 MeV (6+) and 18.538 MeV (8+) than the currently accepted 0+ state at 12.44 MeV. Possible 2+ and 4+ members are considered. The higher 0+ level at Ex=12.44 starts a new 07+ band, and candidates for this band are critically discussed

Study of composition of cosmic rays with energy .7 E 3 Ee

The longitudinal shower development of extensive air showers (EAS) observed in the fly's eye is used to determine the distribution of X sub max, the depth in the atmosphere of the EAS maximum. Data and Monte Carlo simulations of proton and iron primaries are compared. A substantial contribution from light primaries is noted