Maryam Ashrafi, Fabio Anza, and James P. Crutchfield
ABSTRACT: We discuss the Szilard engine whose working fluid consists of a single quantum-mechanical particle. Following Szilard's original solution of Maxwell's Second Law paradox, which turned on physically instantiating the demon (control subsystem), the quantum engine's design parallels the classically-chaotic Szilard Map that operates a thermodynamic cycle of measurement, thermal-energy extraction, and memory reset. We analyze in detail the dynamical mechanisms by which the quantum engine operates, both its thermodynamic costs and the required information processing to observe and control the particle, comparing these in the quantum, semiclassical, and classical limits. We establish Landauer Principles for information-processing-induced thermodynamic dissipation in the quantum and semiclassical regimes.