Recent developments in the study of higher order nonclassical states

Abstract

Our recent observations ort higher order nonclassicality are described. Recently we have shown that a generalized notion of higher order nonclassicality (in terms of higher order moments) can be introduced. Under this generalized framework of higher order nonclassicality, conditions of higher order squeezing and higher order subpoissonian photon statistics are derived. Further, with the help of simple density matrices, it is shown that the higher order antibunching (HOA) and higher order subpoissonian photon statistics (HOSPS) are not the manifestation of the same phenomenon and consequently it is incorrect to use the condition of HOA as a test of HOSPS. It is established that the HOA and HOSPS may exist even in absence of the corresponding lower order phenomenon. It is also shown that the potential sources of Single photon must satisfy the condition of HOA. Most of the intermediate states are shown to satisfy the criteria of HOA. A protocol for comparison of potential Single photon sources (SPS) is reported here and the protocol is used to compare some of the existing proposals of SPS. Further, it is shown that it is possible to derive an arbitrarily large number of criterion for higher order nonclassicality but all of them does not yield new and interesting information.