%0 Journal Article
%T Minimum Total Noise in Wave-Mixing Processes
%A Savita Gill
%A Sunil Rani
%A Nafa Singh
%J International Journal of Optics
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/431826
%X Higher-order squeezing in different optical processes such as seven-wave mixing and five-wave mixing has been studied. The total noise of a field state is a measure of the fluctuations of the field amplitude. It is shown that the minimum total noise ( ) of a higher-order squeezed state always increases with the increase in nonclassicality associated with higher-order squeezing. Thus, from , one can conclude that highly nonclassical states have large amplitude fluctuations. 1. Introduction The concept of the total noise of a quantum state was introduced by Schumaker [1]. As was pointed by Schumaker, the total noise is always greater than or equal to a half and reaches this value only for coherent states. The total noise of a field state increases as the depth of nonclassicality associated with a state increases [2]. A nonclassical state of electromagnetic field is one for which the Glauber-Sudarshan P-function either goes negative or contains derivatives of delta function [3]. Standard deviation of an observable is considered to be the most natural measure of quantum fluctuations associated with an observable [4]. Reduction of quantum fluctuation below the coherent state level corresponds to a nonclassical state. Optical fields in states with purely quantum mechanical properties are the key ingredients of quantum optics. Nonclassical properties of a radiation field such as photon antibunching and squeezing are currently of great interest and have attracted considerable attention owing to its low noise property [5¨C9]. Higher-order squeezing has drawn the greater attention of the community due to the rapid development of techniques for making higher-order correlation measurements in quantum optics [10¨C15]. In the present work, we have reported that the generation of higher-order squeezed state is possible by using seven-wave mixing and five-wave mixing processes, respectively. Further, we have also shown that T min can be used as an indirect measure of nonclassicality of a system associated with higher-order squeezing. 2. Higher-Order Squeezing and Total Noise Higher-order squeezing is defined in various ways. Hong and Mandel [10] and Hillery [12] have introduced the notion of higher-order squeezing of quantized electromagnetic field as generalization of normal squeezing. Amplitude-squared squeezing is defined in terms of operators and as where and are the real and imaginary parts of the square of field amplitude, respectively. and are slowly varying operators defined by and . The operators and obey the commutation relation This leads to the uncertainty
%U http://www.hindawi.com/journals/ijo/2012/431826/