Broadband squeezing of light by pulse excitation

Broadband squeezed states of the electromagnetic field are generated by degenerate parametric downconversion with pulse-light excitation in a Ba(2)NaNb(5)O(15) crystal, in which noncritical type I phase matching is attained. Noise reduction below the level of the vacuum fluctuation is clearly observed over a detection bandwidth from dc to approximately 70 MHz. The minimum noise level obtained in the quiet quadrature is 1.1 dB below the shot-noise level. The scheme used in the present experiment is simple and promising for further improvement of squeezing. The relation between squeezing and parametric fluorescence is discussed quantitatively for the first time to the authors' knowledge.