Squeezing Based On Optomechanical Interaction And Parametric Down Conversion

As applications of squeezing become more widespread,the research about squeezing is getting deeper.Squeezed state whose noise of one of the quadrature variables is below zero-point level,has been of great interest from both fundamental and practical point of view,which greatly promotes the study of squeezing.In the field of quantum optics,the standard way to generate optical squeezing is to pump an optical cavity with a nonlinear crystal inside,which is termed optical parametric amplifier?OPA?.There are many experiment have implemented the generation of squeezing light using parametric down-conversion.In recent years,the research of optomechanical has progressed rapidly,which has attracted the interest from other fields.Among them,the cavity optomechanical has attracted much attention because of its quantum optical characteristic.It has long been realized that squeezing can also be realized in optomechanical systems,where cavity photons are coupled to mechanical motion by radiation pressure.Whether relies on the mechanical resonator effectively mediating a?coherent?Kerr-type3c optical nonlinearity or uses the dissipative nature of the mechanical resonator,squeezing light can be produced.It is well known that one of the most important applications of squeezing light is improves the measurement sensitivity of the interferometer in gravitational wave detection.As the sensitivity requirements for detection increase,the requirements for the generation of squeezing are also increasing.We discuss enhanced optical squeezing with two different interactions,which are optomechanical interaction and parametric down conversion.This article focus on the generation of squeezing in optomechanical system,the main works are as follows:1.squeezing is generated by parametric down conversion.The scheme consider a short segment of the second-order nonlinear crystal,pumped with light of optical frequency 2?.The pump field periodicallydrives the vacuum field at ? between regions of low and high polarisation.This process transforms the vacuum state into a squeezed vacuum state in the output.2.Generation squeezing by using a?classical?bichromatic cavity drive.when an optomechanical cavity is driven by two lasers on the red and blue mechanical sideband,cavity photons are coupled to mechanical motion by radiation pressure,strongly squeezed output light can be generated by using dissipative nature of the mechanical resonator.The output light is maximally squeezed when an impedance matching condition is fulfilled.All incident optical vacuum fluctuations are perfectly absorbed by the mechanical resonator and are replaced by effectively squeezed mechanical noise.This dissipative scheme can directly be used to enhance the intrinsic measurement sensitivity of the optomechanical cavity.3.Enhanced optical squeezing with optomechanical interaction and parametric down conversion.The cavity is driven by three fields,One of them is at frequency 2w₀ for pumping parametric down conversion.The other two are at mechanical sideband frequencies w₀+w_m and w₀-w_m respectively for optomechanical interaction.It is calculated that the combination of the two interactions can enhance the squeezing.Parametric down conversion interaction can strengthen optomechanical interaction to strong coupling regime.