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Kouichi YAMAZAKI Osamu HIROTA Masao NAKAGAWA Tomohiko UYEMATSU Masanori OHYA
It is shown that error correcting code improves an essential perfomance limitation of photon communications with energy loss. The coded photon signals allow us the loss about 13 dB to keep the advantage of photon number state signals while uncoded one is about 7 dB. Furthermore the necessity of weight distribution control of code words is discussed.
Osamu HIROTA Kouichi YAMAZAKI Masao NAKAGAWA Masanori OHYA
This letter presents the theoretical analysis of error properties of coded modulation using several quantum state lights. The direct modulation of general code into light pulse has advantage in the case of the photon state light, while PPM is superior in the case of coherent state light.
Some concepts in information theory are tried to apply to the study of genes. The mutual entropy is used to define a measure indicating the similarity between two genetic sequences. The alignment of sequences is briefly discussed. Some phylogenetic trees are written by using the entropy measure. According to this results, usefulness of information theory is discussed in the study of genes such as molecular evolution.
Masanori OHYA Satoru MIYAZAKI Koji OGATA
We introduce new computer algorithm of multiple alignment as an application of "Simulated Annealing" method. Simulated Annealing has been applied to some combinational optimization problems such as travelling salesman problem. After giving short mathematical explanation of this method, we construct genetic distance and matrix corresponding to the object function in the annealing theory for the multiple alignment. Our method is better than other alignment in the sense that we obtain a result having a smaller value for the genetic distance. We discuss further development along on new method.