Quantum network architecture of tight-binding models with substitution sequences

We study a two-spin quantum Turing architecture, in which discrete local rotations (αm) of the Turing head spin alternate with quantum controlled NOT operations. Substitution sequences are known to underlie aperiodic structures. We show that parameter inputs (αm) described by such sequences can lead here to a quantum dynamics, intermediate between the regular and the chaotic variant. Exponential parameter sensitivity characterizing chaotic quantum Turing machines turns out to be an adequate criterion for induced quantum chaos in a quantum network. © 2000 Taylor & Francis Group, LLC.