Studies on the Amplitude-Squared Squeezed States of Light

B. K. Murzakhmetov, Alexei Vladimirovich Chizhov

S. K. Singh, Swapan Mandal

The higher order moments and hence the amplitude-squared squeezing of input coherent light coupled to a quantum driven harmonic oscillator with time-dependent mass and frequency (DHTDMF) are investigated. Exact analytical expressions for the purpose of investigating the amplitude-squared squeezing of the input coherent light are exhibited. The squeezing in the normal sense of the input coherent light is independent of the driven term. On the other hand, the higher order (amplitude-squared) squeezing is sensitive to the driven term. In order to realize the flavour of the analytical approach, we give an interesting special case for the DHTDMF having ω(t) = ω(0) = ω, and driven term . It is found that the effects of the driven term are negligible if the oscillator is in the off-resonance situation. The condition of strong input coherent light also ensures the suppression of the effects of driven terms. By using a complete analytical method, we give an approximate analytical form of the relevant equations for investigating the amplitude-squared squeezed states. We carefully examine the special situations when the oscillator is underdamped, overdamped and critically damped (from both directions). The possibility of getting amplitude-squared squeezing of the input vacuum field is also discussed. To provide the feelings of the analytical results and hence the deep realizations of the physical system, we give a few results graphically. The realization of the present model in classical and in quantum mechanical pictures are clearly indicated.

Daniel F. Walls

Pierre Meystre, Murray Sargent

Yang Zhan

In this paper the amplitude-squared squeezing in the multiphoton nonlinear optical processes is studied. It is examined that amplitude-squared squeezing can be created in the first order approximation by k-photon unitary operators Sk(z) (K 2) acting on the coherent state |α(|α|≠0) and one can not be created by Sk(z) (K 2, K≠4) acting on the vacuum state. It is found that amplitude-squared squeezing can be created by 4-photon unitary operator S4(z) acting on the vacuum state and this shows that the amplitude-squared squeezing is a new nonclassioal effect of light field which is independent of the second order squeezing, antibunohing and sub-Poisson statistics.

Holger Friedrich Hofmann, Takafumi Ono

We show that the interference between photon pairs emitted by spontaneous parametric downconversion and coherent laser light generates a class of N-photon phase squeezed states characterized by a single squeezing parameter given by N times the ratio of the downconversion amplitude and the squared coherent amplitude.