Mach-Zehnder Interferometer Phase Measurement With Polarization Entangled Photon-Pairs

Quantum precise measurement is an interdisciplinary subject which has been widely concerned in recent years.It is the product of the combination of quantum mechanics and metrics.In the field of metrics,the primary problem of any measurement system is how to obtain higher measurement accuracy.The core of quantum precision measurement is to improve the measurement accuracy of measurement system by using quantum effect,which is the core technology in quantum computing,aerospace,radar guidance and other fields.Optical interferometer is a very mature instrument for precise measurement,and the combination of quantum effect and optical interferometer has become a common solution in the field of quantum precise measurement.For example,the American LIGO observatory,which has repeatedly detected gravitational wave events,is a model of combining quantum effect with Michelson interferometer.In addition,Mach-Zehnder interferometer(MZI)is also widely used in the field of quantum optics and precision measurement.Taking MZI as the basic model,this paper firstly analyzes the distribution law of MZI interferometric fringe theoretically,and builds a classical coherent laser MZI measurement system.The phase information of interferometric fringe is extracted by means of interferometric fringe movement quantity method and frequency domain transformation method,and the phase measurement error of classical coherent laser MZI is calculated.Then it is proved that the phase measurement accuracy of classical coherent laser MZI with N particles is limited to the limit of particle noise of 1??,and a new MZI measurement scheme with polarization entangled photon pairs as the light source is proposed.A scheme for the preparation of polarization entangled source by spontaneous parametric down conversion(SPDC)is designed for two BBO crystals stuck together and their optical axes are perpendicular to each other.Finally,a polarization entangled MZI measurement system is built,and the phase information is extracted by using the method of photon counting and measurement,and the precision measurement of MZI phase based on polarization entangled photon pairs is realized.The experimental results show that compared with the classical coherent light source,the polarized entangled light source will improve the phase measurement accuracy of MZI by 18.54%,which is consistent with the theory.Our work suggests that it is feasible to use polarized entangled photon pairs as the source of MZI to obtain higher phase measurement accuracy.