We show theoretically that by interfering two independent, equally squeezed vacuum fields on a simple 50-50 beam splitter one can produce twin beams with perfect intensity correlation. Using a broadband theory of traveling-wave, parametric down-conversion, we calculate the noise statistics of the difference intensity of the two fields leaving the beam splitter as a function of the relative phase between the two independent squeezed fields. The noise statistics are found to vary from twin photon beams to superthermal fluctuations for a broad range of electronic detection frequencies near zero frequency (dc). In the case of ideal detectors, essentially perfect noise cancellation is predicted for arbitrary degrees of squeezing when the two beams are mixed with the proper phase. The results are fairly robust with respect to the effects of imperfect detection efficiency and unequal squeezing strengths in the two fields.

• Received 16 December 1991

DOI:https://doi.org/10.1103/PhysRevA.46.414