Quantization of Gravitational Waves and Squeezing

The question whether gravitational waves are quantised or not can in principle be answered by the help of correlation measurements. If the gravitational waves are quantised and they are generated by the change of the background metrics then they can be in squeezed state. In a sqeezed state there is a correlation between the phase of the wave and the quantum fluctuations. It is recommended to analyse the data to be obtained by the gravitational detectors from the point of view of such correlations. An explicit formula is derived for the squeezing parameter of the quantised gravitational waves. The head on collision of two identical black holes is analysed as a possible source of squeezed gravitational waves.