It is shown that in a Fabry-Perot cavity the general motion of a mirror from one stationary position to another generates photons even if the initial state is a vacuum. In particular the statistics of the photon states so created are super-Poissonian, non-thermal and, in certain situations, squeezed.
After developing the concept of displaced squeezed vacuum states in the nonunitary approach and establishing the connection to the unitary approach we calculate their quasiprobabilities and expectation values † k a a in general form.Then we consider the displacement of the squeezed vacuum states and calculate their photon statistics and their quasiprobabilities.The expectation values of the displaced states are related to the expectation values of the undisplaced states and are calculated for some simplest cases which are sufficient to discuss their categorization as sub-Poissonian and super-Poissonian statistics.A large set of these states do not belong to sub-or to super-Poissonian states but are also not Poissonian states.We illustrate in examples their photon distributions.This shows that the notions of sub-and of super-Poissonian statistics and their use for the definition of nonclassicality of states are problematic.In Appendix A we present the most important relations for ( ) 1,1 SU treatment of squeezing and the disentanglement of their operators.Some initial members of sequences of expectation values for squeezed vacuum states are collected in Appendix E.
We study the statistical properties of squeezed Kerr states generated by squeezing, with a two-photon parametric process, the output of a Kerr medium whose input is coherent light. The squeezing has the effect of allowing the photon statistics to depend on the Kerr nonlinearity. Without the squeezing the statistics are Poissonian, but after squeezing they may be either sub-Poissonian or super-Poissonian. We also study the Q-function quasiprobability distribution for these states and related distributions associated with the quantum-mechanical phase. Finally, we show that quadrature squeezing can be enhanced and that squeezing and sub-Poissonian statistics can coexist.
An important result from quantum optics and condensed matter physics is the use of radiation-matter interaction to produce light with specific characteristics. In this work, we study a nonstationary atom-cavity system and characterize the physical properties of the emitted light. In particular we deal with a Fabry-Perot cavity with a moving mirror which has an embedded two-level system. The study of the statistical properties is done by means of the second-order correlation function with zero delay, which allows to classify the light emitted by the physical system in three different statistical regimes (Poissonian, sub-Poissonian and super-Poissonian) depending on the relationship between the variance and the mean of the photon number distribution. Therefore, in a range of parameters for which the extraction of excitations from the quantum vacuum is evident, we find that the non-classicality of the emitted light depends strongly on the relationship between the radiation-matter coupling constant and the frequency of modulation of the length of the cavity.