Information dissipation in quantum-chaotic systems: Computational view and measurement induction

Information dissipation, a key concept in solving problems in physics of complex systems (e.g. defining physical reversibility and classical-quantum correspondence), is investigated from viewpoints of computation and measurement. First, a fundamental relationship between energy dissipation and the time required for information erasure is derived in the context of computation processes. Next, we review the nonunitarity and irreversibility in quantum-mechanical measurement processes, discussing the possibility of generating the Schrödinger-cat state (the quantum-mechanical superposition of macroscopically distinguishable states). In a quantum-chaotic system, in particular, suppressed chaotic behaviours can revive by the nonunitary measurements. There, nonunitary information dissipation from the relevant system to an external system (a measurement apparatus) plays essential roles.