Theory Analysis And Preliminary Experimental Stdudy Of Quantum Receivers In Optical Communication System

In the classical optical communication systems, due to the influence of shot noise, the receiver performances of the communication system are limited by the standard quantum limit (SQL). In recent years, with the development of quantum information technology, the optical receivers using quantum properties of light are concerned by re-searchers. Because the quantum detection and measurement technology can extract the information that not be obtained by classical measurement methods. It enables the per-formance of the system outperforming the standard quantum limit, and achieving lower bit error rate and higher channel capacity than classic detection schemes. Nowadays research progress on quantum receivers is still relatively slow. It stays in the theoret-ical study and experimental demonstration stage. There are still many theoretical and experimental problems worthy of study.In this paper, we first review the research progress since the 1960's when the quan-tum receivers were proposed, then focus on following three issues:1. The theory of quantum receiver for QAM signals. So far. quantum receiver for binary modulation signals and phase modulation (PSK) signals have been deeply stud-ied, and a lot of breakthrough have been work out. But for higher order modulation such as QAM signals, the researchers are careless. This article will present several receivers for the QAM signals and compare these three receivers. These receivers include a Bon-durant receiver, adaptive partitioning detection receiver and hybrid receivers. By com-paring three receivers, some information can be applied to design engineering achiev-able quantum receiver scheme for reference.2. Theoretical study of conditional nulling receivers for binary modulation multi-symbol signals. Compared to a single symbol detection scheme, conditional nulling receivers using joint detection are more valuable to research. In this article, we will applied the conditional nulling receiver schemes to the multi-pulse pulse position mod-ulation (MPPM), coding OOK modulation signals, coding BPSK modulation signals. On this basis, through optimizing the receive policy, the error probabilities of the re-ceivers are reduced below the SQL of the classic detection scheme.3. Initial experiment research of the quantum receivers. As an initial experimen-tally demonstration work, we implement the Kennedy BPSK receiver in this paper to preliminary validate the Kennedy receiver theory. Experiment results show that our Ke- nendy receiver can outperform the SQL in the same system effiency condition. It is the first time to demonstrate the quantum receiver theory experimentally. By replacing the modulator in the phase of the preparation stage and the receive stage, such receiver can, in principle, be applied to arbitrary PSK. signals, QAM signals and binary modulation multi-symbol signals.