PT Unknown AU Shcherbatenko, M Elezov, M Sych, D Goltsman, GN TI Optimal fiber optic scheme for sub-SQL quantum receiver realization SE J. Phys.: Conf. Ser. PY 2020 BP 012140 VL 1695 DI 10.1088/1742-6596/1695/1/012140 DE sub-SQL; below quantum limit; QL; system quantum limit; SQL AB Practical implementation of high-precision quantum measurements is an important problem in modern science. One of the main parts of the quantum receiver is the optical scheme. We developed and tested several optical circuits based on different types of interferometers, namely Sagnac-based scheme, Mach-Zehnder-based scheme, and Michelson-based scheme. All these schemes are assembled with optical fibers and fiber-optic components, since the fiber-optic implementation is closest to application in practical devices. Schemes were evaluated according to two main criteria: extinction and interference stability. On the basis of the obtained data, it can be concluded that the most suitable is the scheme based on the Mach-Zehnder interferometer. In continuous mode, we were able to obtain an interference extinction about 30 dB with acceptable temporal stability. ER