Theory Of Quantum Precision Ranging Ang Data Processing Technique Research

HBT interferometer is one of the key means of quantum precision measurement, which gets the result by measuring the second-order correlation function of the light field. Entangled photon pairs are affected by group velocity dispersion while transferring in fibers in HBT ranging experiment. Thus, the second-order correlation function will get broadened and shifted. The longer the distance, the larger the impact of group velocity dispersion gets. These phenomena will lower the precis ion in a long-distance ranging experiment, so they have to be compensated in order to get a more accurate ranging result. In this case, the after treatment system is very important, which is mainly to get the ranging result and eliminate errors as along as improve the measurement accuracy.The after treatment module is mainly divided into three parts, known as data collection, data analysis and error elimination. Data collection has two modes: the software mode and the hardware mode. In the software mode, data is collected by hardware and is then processed by software on computer to get the ranging result. In the hardware mode, we process data while collecting to realize a real-time processing system. We use coincidence counting in data analysis, which jointly process data of both the signal path and the idle path and get the second-order correlation function. We use fitting algorithm to eliminate random errors as long as compensation to eliminate errors brought by group velocity dispersion.