Phase control of higher-order squeezing of a quantum field

In a recent experiment [Phys. Rev. Lett. 88 (2002) 023601], phase-dependent photon statistics in a cw system has been observed in the mixing of a coherent field with a two-photon source. Their system has the advantage over other atomic transition-based fluorescent systems. In this paper, we examine further the squeezing properties of higher-order quantum fluctuations in one of the quadrature components of the combined field in this system. We demonstrate that efficient and lasting higher-order squeezing effects could be observed with proper choice of the relative phase between the pump and coherent fields. This nonclassical feature is attributed to a constructive two-photon interference. Relationship between the second- and higher-order squeezing of the field is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.