How do quantum cellular automata differ from quantum Turing machines and quantum circuits in terms of computational model and capabilities?

Quantum cellular automata differ from quantum Turing machines and quantum circuits in their computational model and structure. QCA are inherently parallel and decentralized, with computation occurring simultaneously across an array of cells, each updating based on local rules. In contrast, quantum Turing machines and quantum circuits typically involve sequential operations and a centralized control structure. QCA are particularly suited for simulating spatially extended quantum systems and can provide insights into decentralized quantum processes, while quantum Turing machines and circuits are more general-purpose quantum computation models.