Limits of Landauer’s Principle and the Second Law of Thermodynamics

Since 1857, the second law of thermodynamics has faced the challenge of Maxwell's imagined demon. The widely accepted response to this challenge suggests that the demon requires a bit of information to function, and according to Landauer's principle, the erasure of this bit must offset the entropy reduction achieved by the demon. Recent studies involving two-state physical systems subject to thermal fluctuations at the nanoscale have aimed to either prove Landauer's principle or to demonstrate Szilard engines or Maxwell's demons in practice. We developed the equations and a numerical model to simulate the evolution of these systems. The results highlight the distinction between thermodynamic entropy and information entropy. They also demonstrate that Landauer’s principle has a limited range of applicability and that, using a two-state memory, it is possible to eliminate a small amount of entropy without expending energy—challenging the second law of thermodynamics.