Generation And Application Of Squeezed Light Field

In the past few decades,in addition to studying the basic concepts of quantum science,quantum optics has developed rapidly,especially in squeezed state light field.Squeezed state is a coherent state whose noise distribution is compressed,which is a non-classical phenomenon.Since the quantum noise of one of its orthogonal components is lower than the classical scatter noise limit,we can apply the compressed state light field in many fields,such as precision measurement,quantum communication,quantum radar,etc.There are many means the generation of squeezed state light field,in which optical parametric oscillation is a very effective method,it is in a OPO cavity,according to the nonlinear effect of crystal optical parametric down-conversion process,the advantage of this approach is in the process of producing noise on the interference effect is small and the final preparation of squeezed state from the relatively stable in the case of high purity.In loss produced in the process of the squeezed state,system,lock chamber and the stability of the phase and the detection efficiency of detection system is to restrict the main factors of the compression degree of light,including light path system loss caused by all kinds of lens in the escape of the linear loss,cavity efficiency,output coupling mirror transmission loss,the nonlinear effect of cavity loss and cavity detuning,In addition to the system in the process of loss and the light transmission in the optical path loss,the loss caused by regulating interference visibility not 100%and balance homodyne detector photoelectric diode in the quantum efficiency is not high and the loss caused by the phase stability mainly including pump light and signal light phase,background light and signal light of phase jitter,etc.In addition,parasitic interference,environmental noise and poor pattern matching will also reduce the degree of compression,so we comprehensively explore the influence factors of these aspects.It is the most commonly used method to obtain the Schrodinger cat state by subtracted photons from the vacuum compressed state.We applied the vacuum compressed state prepared to the Schrodinger cat state filter part of the experiment,and ensured the stability of the compressed vacuum state by analyzing and optimizing various influencing factors.In this paper,we introduce the design of filtering part for preparing vacuum compressed state and Schrodinger cat state,as well as the measurement method for the length of filtering cavity.We optimize the optical field for preparing compressed state by analyzing the system loss and phase jitter to balance the zero-beat detection system.Then,according to the requirements of filtering design for preparing cat state,In terms of theoretical analysis,the cavity length of the filter cavity should meet the condition 189μm>l_fc>119μm.It is difficult to measure the cavity length with traditional methods,so we use the ancient dependent phase shift of the higher order transverse mode to measure the cavity length 141μm,which meets the requirements of our design and is applied in the filtering part of the Schrodinger cat state experiment.