Estudo da Correlação no Espalhamento Raman Stokes e anti-Stokes da água

Abstract

In this work we study the correlated Stokes and anti-Stokes Raman scattering, called here SaS. The SaS is an event where the same phonon participates in the of Stokes and anti-Stokes scattering processes. This process is not considered in current treatments of Raman scattering and can bring changes in the use of Raman spectroscopy for localtemperature measurements. Furthermore, these photons emerge as an important source of correlated photons pairs, widely used in quantum information, for example in implementing a quantum memory. We checked, by measurements of coincidence counting, that the Stokes and anti-Stokes photons generated in the Raman scattering from water, morespecifically the bands at }1644 1 concerning the angle variation mode between the H atoms, are quantum correlated. We get a value of 2(0) 517, much higher than what has been measured in others materials, as reported in the literature. We found that theintensity of the anti-Stokes signal has a quadratic dependence on the laser power, being another indication of the SaS occurrence. The value of 2(0) decays to high power values, in agreement with theoretical predictions. We have also obtained evidences that the SaScorrelation exhibits a dependence on the S and aS photon polarizations and can thus be exploited in future entanglement experiments.