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\bibitem{Sych_etal2018} Sych D, Shcherbatenko M, Elezov M, Goltsman GN. Towards the improvement of the heterodyne receiver sensitivity beyond the quantum noise limit. In: Proc. 29$^{th}$ Int. Symp. Space Terahertz Technol.; 2018. p. 245--7.

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