Studies on modulation and demodulation methods for quantum state control communication

Masao Osaki, Masao Nakagawa

Hui Zhang

Quantum communication is a theory based on the idea that quantum states can be transferred from one place to another. This theory has several advanced features. Specifically, it has high security, low time cost and low power overhead. Quantum information can make the execution of tasks much less efficient. However, much research has been done to achieve quality control by proposing utterly new security algorithms. The modulation and demodulation tasks of QC have not been sufficiently studied. Therefore, the modulation and demodulation methods are systematically summarised and analysed according to the two types of "signal type" and "modulation method type", respectively. In summary, PSK modulation outperforms OOK modulation in SRM-based multi-user detection schemes. The serious shortcomings of generalised secrecy modulation in terms of information-theoretic security mean that the security of GCM is not good. Moreover, there are many practical problems still required to be addressed. For example, the computational complexity characterisation and optimisation with correlation type receivers. Especially for ultra-high SE improvement have a large N parameter. Switching the slits at a reliable and efficient pace is a challenge. The high SE reduce the importance of speed. The complexity of the ML decoder combing with the joint modulation/coding should be explicitly modelled. Finally, the design of optical set-up in combination with amplifier structures recovering the loss due to MPD design.

Saikat Guha, Jonathan L. Habif, Masahiro Takeoka

Optical pulse-position modulation (PPM) is one of the primary modulation formats being investigated for use in deep-space communications, as well as terrestrial fiber optical communications. We consider the problem of demodulating M-ary optical PPM waveforms, and propose a structured receiver whose mean probability of symbol error is smaller than all known receivers, and approaches the Helstrom (quantum) limit of the minimum probability of error (MPE) of discriminating between the coherent-state PPM signals. The receiver uses photodetection coupled with optimized phase-coherent optical feedback control through the PPM pulse slots and a phase-sensitive parametric amplifier. We present a general framework of optical receivers known as the ‘conditional pulse nulling receiver’, and present new results on ultimate limits and achievable regions of the trade-off space between the spectral versus photon efficiency of PPM, for the single-spatial-mode far-field pure-loss optical communication channel.

Osamu Hirota

Hunag Chun Hui

In this paper， we introduced a system of coherent optical detection with homodyne， which implementing coherent optical communication，our own design based on the principle of coherent optical communication. IN the system, PCI6111E was useed as a data acquisition(DAQ) module. Alice and Bob’s control procedure by their computers under the LabVIEW. The synchronous detection and DAQ were carried out on the system. The signals were processed, displayed and measured. The Experimental results show that by light-synchronization and LabVIEW procedure control, each function module work together in cooperation, include Alice’s acousto-optic modulator and electro-optical modulator, Bob’s data acquisition and phase adjustment by PZT. The coherent optical information could be transitted by Alice and real-time demodulated by Bob.

Siyu Song, Chuan Xi Wang