Showing papers by "Stephan Schiller published in 2003"

Modern Michelson-Morley experiment using cryogenic optical resonators.

Abstract: We report on a new test of Lorentz invariance performed by comparing the resonance frequencies of two orthogonal cryogenic optical resonators subject to Earth's rotation over $\ensuremath{\sim}1\text{ }\mathrm{y}\mathrm{r}$. For a possible anisotropy of the speed of light $c$, we obtain ${\ensuremath{\Delta}}_{\ensuremath{\theta}}c/{c}_{0}=(2.6\ifmmode\pm\else\textpm\fi{}1.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}$. Within the Robertson-Mansouri-Sexl (RMS) test theory, this implies an isotropy violation parameter $\ensuremath{\beta}\ensuremath{-}\ensuremath{\delta}\ensuremath{-}\frac{1}{2}=(\ensuremath{-}2.2\ifmmode\pm\else\textpm\fi{}1.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$, about 3 times lower than the best previous result. Within the general extension of the standard model of particle physics, we extract limits on seven parameters at accuracies down to ${10}^{\ensuremath{-}15}$, improving the best previous result by about 2 orders of magnitude.

Molecular dynamics simulation of sympathetic crystallization of molecular ions

Abstract: It is shown that the translational degrees of freedom of a large variety of molecules, from light diatomic to heavy organic ones, can be cooled sympathetically and brought to rest (crystallized) in a linear Paul trap. The method relies on endowing the molecules with an appropriate positive charge, storage in a linear radio frequency trap, and sympathetic cooling. Two well-known atomic coolant species ${}^{9}{\mathrm{Be}}^{+}$ and ${}^{137}{\mathrm{Ba}}^{+}$ are sufficient for cooling the molecular mass range from 2 to 20 000 amu. The large molecular charge required for simultaneous trapping of heavy molecules and of the coolant ions can easily be produced using electrospray ionization. Crystallized molecular ions offer vast opportunities for novel studies.

Transportable, highly sensitive photoacoustic spectrometer based on a continuous-wave dualcavity optical parametric oscillator

Abstract: We present an all solid state, transportable photoacoustic spectrometer for highly sensitive mid-infrared trace gas detection. A complete spectral coverage between 3.1 and 3.9 µm is obtained using a PPLN-based continuous-wave optical parametric oscillator pumped by a Nd:YAG laser at 1064 nm. A low threshold is achieved by resonating the pump, and spectral agility by employing a dual-cavity setup. An etalon suppresses mode-hops. Active signal cavity stabilization yields a frequency stability better than ±30 MHz over 45 minutes. Output idler power is 2×100 mW. The frequency tuning qualities of the OPO allow reliable scan over gas absorption structures. A detection limit of 110 ppt for ethane is achieved.

Precision test of the isotropy of light propagation

Abstract: We report on a test of the isotropy of light propagation performed by comparing the resonance frequencies of two orthogonal cryogenic optical resonators subject to Earth’s rotation over ∼1 yr. The technical aspects of the experiment are discussed and the analysis of the data is presented in detail. For a possible anisotropy of the speed of light c, we obtain Δθc/c0=(2.6±1.7)×10-15. Within the general extension of the standard model of particle physics, we extract limits on seven parameters at accuracies down to 10-15, improving the best previous result by about two orders of magnitude. Within the Robertson–Mansouri–Sexl test theory, this implies an isotropy-violation parameter β-δ-1/2=(2.2±1.5)×10-9, about three times lower than the best previous result.

A continuous-wave optical parametric oscillator for mid infrared photoacoustic trace gas detection

Abstract: We present a continuous-wave, pump-resonant, singly-resonant optical parametric oscillator based on periodically poled lithium niobate in a linear dual-cavity design which is applied for photoacoustic trace gas detection between 2.35 and 3.75 μm. Pumped by a Nd:YAG laser at 1064 nm a single-frequency output power of 2 x 100 mW is achieved. The frequency tuning qualities of the OPO allow to scan gas absorption structures. An ethane detection limit of 110 ppt is achieved. Sensitivity, tuning qualities and compact design make this OPO an ideal laser source in a transportable photoacoustic spectrometer.

Ultra-cold molecules in Coulomb crystals

Abstract: Ultracold molecular hydrogen (D/sub 2//sup +/) is produced by sympathetic cooling in a linear Paul trap. With this method the translational degrees of freedom of the molecules are cooled by Coulomb interaction with laser-cooled /sup 9/Be/sup +/. This work shows that sympathetic cooling and crystallization is possible down to mass ratios of 0.45. Using molecular dynamics simulations, the mass range for sympathetic cooliing is predicted. By employin a light and a heavy species of laser-cooled ions (/sup 9/Be/sup +/ and e.g. /sup 137/Ba/sup +/) the mass range from 2 to 20 000 amu, i.e. from the simplest molecule to complex proteins, can be sympathetically cooled.