Observation Of Generation Process For Pulsed Squeezed Vacuum State From Polarized Self-Rotation Effect

Non-classical states of light have showed great potential of application in the field of quantum information and communication.Compared to classical coherent light,squeezed light plays an active role of alternating noise and some unique properties.Quantum information protocols and optical measurements are always limited by quantum noise,the birth of squeezed light and squeezed vacuum light are potentially useful for optimizing the sensitivities.Although it has been the heat for the last two decades,but the whole center was about generating high quality squeezed light for other application,meanwhile,the natural state of squeezed light is massively important.We noticed that,by far,no group have looked into what happened in pulsed squeezing process,like establishing period and dynamic process.We use a self-polarized rotation effect to generate squeezing vacuum through a Rb87 vapor for interaction medium,for signal enhancement and less extra noise,we use balanced Homodyne detection to measure the quadrature field.The system goes through a classical coherent state to quantum squeezing state.This reduction of time can be used for quantum information protocols in the future.As an alternative to the crystal compression source,the nonlinear optical process in the atomic medium can also produce a nonlinear light field.For example,the four-wave mixing process can produce a two-mode squeezed state and an entangled light field with a nanosecond pulse width,And a similar non-degenerate process can produce orthogonal compression vacuum field,which is called polarized self-rotation squeezing.The optimal noise compression of this method achieves-3dB.However,most of the researches on polarization-dependent rotation are the generation of continuous light field.For the generation of pulsed compression field,the establishment of pulse compression state and the evolution of noise intensity of signal light field are rarely involved.In this paper,the averaged squeezing level is-1.1dB,a squeezing establishing time of 75 ?s is observed through optical Homodyne detection.This work provide a protocol for further studies in variations from classical state to quantum state.