Quantum Cellular Automata
摘要
In 1982, Feynman, considered the possibility of using cellular automata (CAs) both as models of quantum systems and as quantum computer architecture, driven by the fact that CAs are a model for universal computation. Yet, their quantum counterpart, quantum cellular automata (QCAs), are limited by the no-coning theorem and the no-go lemma and thus, except for the trivial case, do not constitute a universal computational model. To overcome this obstacle, we consider discrete-time quantum walks which reproduce unitary evolution in space and have been proven to be a universal quantum computation model. By combining them with quantum cellular automata, which reproduce unitary evolution in time, a new model of quantum computation is possible. In this chapter, we formulate discrete-time quantum walks on QCAs and present various applications that are different in nature, to emphasize the universality of the model.