Maximizing fluctuation exploitation in a simple information ratchet*

At the dawn of statistical mechanics, Maxwell proposed a thought experiment where acquiring information about a system can allow the extraction of work from a heat reservoir, something seemingly forbidden by the Second Law of Thermodynamics. We present an analagous Maxwell Demon system whereby a particle with mass can be lifted by a spring attached to a stage without direct effort by simply observing its motion as it bounces up and down. This device is an information ratchet, using information to convert thermal fluctuations into stored work, which may be later used to power other processes. We find, for this device, that the maximal rate of energy extraction is not limited by the observation rate but rather by the physical parameters of the ratchet: the size of the particle, the stiffness of the spring, the temperature of the surrounding medium, and the friction coefficient associated with the particle motion.