Showing papers by "Karsten Danzmann published in 2001"
TL;DR: In this article, the phase shift of the frequency fixed coupling laser in dependence of the probe laser frequency relative to an off-resonant reference laser was observed in a three-level system.
Abstract: Using three phase-locked lasers, we have observed in a three-level system the phase shift of the frequency fixed coupling laser in dependence of the probe laser frequency relative to an off-resonant reference laser. In the vicinity of the two-photon resonance, the system exhibits electomagnetically induced transparency and we show that the dispersion of coupling and probe field shows different spectra if the probe field frequency is tuned. The parametric dispersion of the coupling field is measured on a cesium atomic beam with a heterodyne interferometer over several decades of coupling and probe laser power. Even with coupling powers in the nW range, the interferometer gives a good signal-to-noise ratio. The results are in good agreement with a numerical simulation of a semiclassical model. Analytical expressions for the dispersion are given.
13 citations
TL;DR: The space project LISA as discussed by the authors is a cornerstone mission in the field of fundamental physics, sharing its goal and principle of operation with the ground-based interferometers currently under construction: the detection and measurement of gravitational waves by laser interferometry.
Abstract: The space project LISA is approved by ESA as a cornerstone mission in the field of ‘fundamental physics’, sharing its goal and principle of operation with the ground-based interferometers currently under construction: the detection and measurement of gravitational waves by laser interferometry. Ground and space detection differ in their frequency ranges, and thus the detectable sources. At low frequencies, ground-based detection is limited by seismic noise, and yet more fundamentally by ‘gravity gradient noise’, thus covering the range from a few Hz to a few kHz. On five sites worldwide, detectors of armlengths from 0.3 to 4 km are being built, two of them in Europe ( GEO and VIRGO ). They will progressively be put in operation between 2001 and 2003. Future improved versions are being planned, with data not until 2008, i.e. near the launch of the space project LISA . It is only in space that detection of signals below, say, 1 Hz is possible, opening a wide window to a different class of interesting sources of gravitational waves. The project LISA consists of three spacecraft in heliocentric orbits, forming a triangle of 5 million km sides.
4 citations
01 Jan 2001
TL;DR: The GEO 600 interferometer as discussed by the authors uses a four-pass delay line and signal recycling to search for faint sources of only slowly varying frequency (pulsars, close binaries).
Abstract: The last few years have brought a great break-through in the quest for earth-bound detection of gravitational waves: at five sites, laser-interferometric detec- tors, of armlengths from 0.3 to 4 km, are being built. These projects have in common that one prominent noise source, the shot noise, is reduced by the use of power re- cycling. By using advanced optical technologies early on, the German-British project GEO 600, although only intermediate in size (600 m), has good chances for a compet- itive sensitivity, at least with the first versions of the larger detectors. Particularly the use of the so-called signal recycling technique will allow to search for faint sources of only slowly varying frequency (pulsars, close binaries). The talk will describe the par- ticular topology of the GEO 600 interferometer, characterized by the use of a four-pass delay line and signal recycling. The major noise sources, and the experimental effort aiming at their reduction, will be discussed. The current status of the construction of GEO 600 will be outlined (civil engineering, vacuum, optics). The research and de- velopment activities at the experimental sites (Garching, Glasgow, Hannover) will be given broad emphasis. First science runs of GEO 600, well in time with those of other ground-based interferometers, are expected in the year 2001.
2 citations
11 May 2001
TL;DR: In this article, a high sensitivity spectroscopic method was developed to study optical properties of an atomic beam, which can be taken as a two level system in a simplified picture, and it was possible to measure simultaneously both absorption and phase shift.
Abstract: Summary form only given. A high sensitivity new spectroscopic method was developed to study optical properties of an atomic beam. It was possible to measure simultaneously both absorption and phase shift. We used calcium and the transition at 423 nm, which can be taken as a two level system in a simplified picture.
14 Mar 2001
TL;DR: The first ground-based interferometers are scheduled to go into operation in 2001 and a space-based detector is expected to be launched in 2010 as mentioned in this paper, which will complement each other because the gravitational wave spectrum extends over many decades in frequency.
Abstract: Small prototypes of gravitational wave detectors have been under development for over 30 years. But it is only now that we have the necessary technology available to build large instruments with good sensitivity. After several years of construction, the first ground-based interferometers will go into operation in 2001 and a space-based detector is expected to be launched in 2010. These instruments will complement each other because the gravitational wave spectrum extends over many decades in frequency. Ground-based detectors can only observe the audio-frequency regime above 1 Hz, while sources in the low-frequency regime are only accessible from space because of the unshieldable background of local gravitational noise on the ground.
11 May 2001
TL;DR: In this paper, the absorption and dispersion properties of a coherent prepared media were investigated on a three level Cs atomic system and the experiments were done on a Cs atom beam.
Abstract: Summary form only given. The field of atom manipulation using laser light has experienced a rapid growth in the recent years. By the interaction of the atoms with laser light it is possible to design media with desired optical properties such as transparent media showing negative or positive dispersion. Negative dispersive transparent media can be used e.g. to realize an optical cavity with large build up but broadband response (white light cavity) or to demonstrate superluminal light propagation. It has also been demonstrated that positive dispersive media can exhibit steep dispersion leading to small absolute values of the group velocity (slow light, see e.g.) or reducing e.g. the line width of a cavity relative to the line width of the empty resonator.We report on recent experiments on investigation the absorptive and dispersive properties of a coherent prepared media, that shows electromagnetically induced transparency on extremely narrow dark resonances. We have carried out the experimental study of a two-photon excitation via quantum interference in a three level Cs atomic system. The experiments were done on a Cs atomic beam.