Small-vibration detector for a gravitational antenna

There is a fundamental threshold value of the vibration amplitude of a macroscopic oscillator, at the level of 1 x 10 to the -17th 3 x 10 to the -18th cm. A highly stable microwave source with a narrow spectral line has been used in a new method for measuring vibrations. A vibration-amplitude resolution of 2 x 10 to the -17th cm has been achieved with an averaging time of 10 s.