It is well known that during the ℓth-subharmonic generation general ℓ-photon states evolve from an arbitrary state of the pump mode. For the second-subharmonic generation with an initial coherent state the assumption of pump nondepletion, the so called parametric approximation, is very useful for obtaining closed formulas. The resulting state then is an ordinary squeezed vacuum. The parametric approximation is ineffective for ℓ > 2 not only because closed formulas are not obtained, but also because it is proven that no quantum state is defined for nonzero higher-order squeezing [1]. This finding motivated a definition of the ℓ-photon coherent state [2],

Date Published: 1 September 1996
PDF: 2 pages
Proc. SPIE 2778, 17th Congress of the International Commission for Optics: Optics for Science and New Technology, 2778BP (1 September 1996); doi: 10.1117/12.2316110

Published in SPIE Proceedings Vol. 2778:
17th Congress of the International Commission for Optics: Optics for Science and New Technology
Joon-Sung Chang; Jai-Hyung Lee; ChangHee Nam, Editor(s)