Accueil du site > Atomes, cavités et photons > Techniques expérimentales > Dispositif expérimental. > Technologie micro-onde
Technologie micro-onde
The generation and control of microwave fields plays an essential role in our experiments, both for cavity characterization and for the operation of the Ramsey interferometer. We have developed original microwave techniques, in close collaboration with P. Goy and the ABmm company.
These experiments require extremely monochromatic millimeter-wave sources for the Ramsey interferometry and the control of tiny field intensities, at the single photon levels, when we prepare the cavity mode in a cohrent state.
Instead of using directly millimeter-wave sources, we thus prefer to use X-band sources, around 12.7 GHz (Yig oscillators or Anritsu microwave synthesizers). We generate the fourth harmonic of the source in a Shottky diode, and feed it in the cryostat by a waveguide.
These X-band sources are all phase-locked to the same reference quartz oscillator. They present thus a negligible linewidth and are all phase-coherent, an essential asset for complex manipulations of atomic coherences.
Fast PIN diodes are used to switch the microwave power on or off, with an excellent time resolution.
By reducing the power of the X-band frequency, the millimeter-wave power can be reduced in huge amounts. Calibrated millimeter-wave attenuators are used for a precise tuning of the injected power.
For the detection of millimeter wave fields (e.g. cavity transmission when applicable), we use an harmonic heterodyne reception scheme. The incoming signal beats in a Shottky diode with the fourth harmonic of a frequency-offset coherent source, generated by the same diode. The beating note amplitude and phase are finally measured. This scheme, developed for our experiments by P. Goy and M. Gross is at the heart of a millimeter-wave network analyzer developed by ABmm (CNRS-ABmm patent).
Dans la même rubrique :
