| In recent years,with the rapid development of science and technology,various areas have higher and higher requirements for measurement accuracy.Since it can beat the standard quantum limit on classical measurement,quantum precision measurement plays an important role in various areas.Laser interferometer stands out in the field of precision measurement for its advantages,such as fast response,high accuracy and no contact.Electro-optical sensors based on common-path interferometer are thus widely used in E-field measurement for their better temperature stability and controllable optical bias.However their measurement accuracy is limited by the electro-optical coefficient of the crystal.In general,increasing the optical power can improve the measurement accuracy,while the high power will reduce the responsivity of the crystal.Therefore,it is particularly important to improve the measurement accuracy of the electro-optical sensor without changing the optical power or electro-optical coefficient of the crystal.To this end,this paper proposes to use a common-path quantum interferometer to enhance the measurement accuracy of the electro-optical sensor.This paper generates a squeezed vacuum light through the polarization self-rotation effect of the rubidium atom,and injects it as an input state instead of the vacuum light into the common-path interferometer to realize a quantum interferometer.A quantum interferometer can be used to enhance signal-to-noise ratio and voltage sensitivity of the classical electro-optical sensor.In experiment,a 1.60 d B squeezed vacuum light can obtain a 1.12 d B quantum enhancement,which can effectively improve the measurement accuracy limited by the crystal electro-optical coefficient.Meanwhile,in order to obtain better measurement accuracy,we propose a method by using a weak magnetic field to improve the squeezing degree of the squeezed vacuum light.Our experimental results illustrate that extra magnetic field perpendicular to the propagation and polarization direction of pumping light can increase the squeezing degree from 1.60 d B to 2.10 d B. |
