Optomechanical Stochastic Resonance in a Macroscopic Torsion Oscillator

Linear mechanical oscillators have been applied to measure very small forces, mostly with the help of noise suppression. In contrast, adding noise to non-linear oscillators can improve the measurement conditions. Here, this effect of stochastic resonance is demonstrated in a macroscopic torsion oscillator, for an optomechanical non-linear potential. The signal output is enhanced for a sub-threshold electronic signal. This non-linear oscillator serves as a model system for the enhancement of signal-to-noise ratio in high precision optomechanical experiments.Comment: 4 pages (double column), 3 figure

LAPR: An experimental aircraft pushbroom scanner

A three band Linear Array Pushbroom Radiometer (LAPR) was built and flown on an experimental basis by NASA at the Goddard Space Flight Center. The functional characteristics of the instrument and the methods used to preprocess the data, including radiometric correction, are described. The radiometric sensitivity of the instrument was tested and compared to that of the Thematic Mapper and the Multispectral Scanner. The radiometric correction procedure was evaluated quantitatively, using laboratory testing, and qualitatively, via visual examination of the LAPR test flight imagery. Although effective radiometric correction could not yet be demonstrated via laboratory testing, radiometric distortion did not preclude the visual interpretation or parallel piped classification of the test imagery

Observation of opto-mechanical multistability in a high Q torsion balance oscillator

We observe the opto-mechanical multistability of a macroscopic torsion balance oscillator. The torsion oscillator forms the moving mirror of a hemi-spherical laser light cavity. When a laser beam is coupled into this cavity, the radiation pressure force of the intra-cavity beam adds to the torsion wire's restoring force, forming an opto-mechanical potential. In the absence of optical damping, up to 23 stable trapping regions were observed due to local light potential minima over a range of 4 micrometer oscillator displacement. Each of these trapping positions exhibits optical spring properties. Hysteresis behavior between neighboring trapping positions is also observed. We discuss the prospect of observing opto-mechanical stochastic resonance, aiming at enhancing the signal-to-noise ratio (SNR) in gravity experiments.Comment: 4 pages, 5 figure

Les isolants du VIVITRON

Les résultats de nombreux essais haute tension des différents isolants (composite verre-époxyde et plots) utilisés dans le VIVITRON sont reportés. Les tests de faisabilité d'une section accélératrice à l'échelle 1 sont décrits

Photon-Atom Coupling with Parabolic Mirrors

Efficient coupling of light to single atomic systems has gained considerable attention over the past decades. This development is driven by the continuous growth of quantum technologies. The efficient coupling of light and matter is an enabling technology for quantum information processing and quantum communication. And indeed, in recent years much progress has been made in this direction. But applications aside, the interaction of photons and atoms is a fundamental physics problem. There are various possibilities for making this interaction more efficient, among them the apparently 'natural' attempt of mode-matching the light field to the free-space emission pattern of the atomic system of interest. Here we will describe the necessary steps of implementing this mode-matching with the ultimate aim of reaching unit coupling efficiency. We describe the use of deep parabolic mirrors as the central optical element of a free-space coupling scheme, covering the preparation of suitable modes of the field incident onto these mirrors as well as the location of an atom at the mirror's focus. Furthermore, we establish a robust method for determining the efficiency of the photon-atom coupling.Comment: Book chapter in compilation "Engineering the Atom-Photon Interaction" published by Springer in 2015, edited by A. Predojevic and M. W. Mitchell, ISBN 9783319192307, http://www.springer.com/gp/book/9783319192307. Only change to version1: now with hyperlinks to arXiv eprints of other book chapters mentioned in this on