
Thermodynamic costs of information processing, erasure, and time evolution.Information thermodynamics is the field that merges information theory with thermodynamics, exploring how the processing of information—storing, erasing, transmitting—has physical consequences in terms of energy and entropy. It addresses questions like: How much energy does it cost to erase a bit of information? Can information be used to extract work from a heat bath? This field has profound implications for the physics of computation, the foundations of the second law of thermodynamics, and the limits of miniaturization in technology.
The field was initiated by Rolf Landauer in 1961 with his principle on erasure. Charles Bennett in the 1970s and 1980s extended these ideas to show that computation can be done reversibly, and that information itself has a thermodynamic value. The concept of Maxwell's demon, though dating back to 1867, was fully resolved using these ideas in the 1980s.
The central result is Landauer's principle, which states that erasing one bit of information necessarily dissipates at least kT ln(2) of energy as heat, where k is Boltzmann's constant and T is the temperature. This is because erasing a bit reduces the number of possible states of the memory, which decreases its entropy, and the second law requires that this entropy be transferred to the environment. Conversely, information can be used to do work: a 'Maxwell's demon' that measures the state of a particle and uses that information to extract work can, in principle, convert information into useful energy, but only if the demon's own memory is eventually erased, paying the thermodynamic cost.
It sets fundamental limits on the energy efficiency of computers, guides the design of low-power electronics, and is used in research on quantum computing and nanoscale heat engines.
In 2012, researchers experimentally verified Landauer's principle using a single colloidal particle trapped in a double-well potential, measuring the exact heat dissipation of erasing one bit of information.










