Quantum noise consists of shot noise and radiation pressure noise; the minimum of the sum of both makes the standard quantum limit. However, we can reduce the radiation pressure noise and even beat the standard quantum limit by utilizing the correlation between the quantum noise of the incident light and the Doppler noise of the reflected light caused by the shaken mirror. We are now doing an experiment to demonstrate the principle.
Link to the page of Quantum non-demolition research

A mirror in a gravitational wave detector is shaken by ground motion, thermal noise, and radiation pressure noise, producing mirror displacement noise. However, we can cancel the displacement noise while maintaining the gravitational wave signal by utilizing the fact that gravitational wave and mirror motion affect light differently and by taking an appropriate combination of the outputs of multi-interferometers. We invented this method and already demonstrated the principle by experiment.

Since a mirror in a gravitational wave detector is suspended, it suffers from ground motion and pendulum thermal noise. However, we can build a detector free from seismic noise and thermal noise by throwing up the mirror repeatedly to realize a continual free-fall status. This is also our idea and we plan to do a prototype experiment.