DIFFERENCE-PHASE SQUEEZING FROM AMPLITUDE SQUEEZING BY MEANS OF A BEAMSPLITTER

A classical analysis of two equal intensity coherent fields incident o n a beamsplitter shows that the difference-phase noise of the output d epends only on the noise in the difference of the amplitudes of the in put fields and not on their phase noise. This suggests that in the qua ntum mechanical case squeezing in the amplitudes of the input beams ca n lead to squeezing in the phase difference of the output beams. We sh ow that this is true. We also find the phase properties of the output when the input consists of two number states with an equal number of p hotons. The difference phase distribution consists of two narrow peaks , at theta = 0 and theta = pi. States with small phase difference nois e should be useful in the measurement of phase shifts.