  In 1961, R. Landauer proposed the principle that logical irreversibility is
associated with physical irreversibility and further theorized that the erasure
of information is fundamentally a dissipative process. Landauer posited that a
fundamental energy cost is incurred by the erasure of information contained in
the memory of a computation device. His theory states that to erase one binary
bit of information from a physical memory element in contact with a heat bath
at a given temperature, at least kT ln(2) of heat must be dissipated from the
memory into the environment, where k is the Boltzmann constant and T is the
temperature. Although this connection between information theory and
thermodynamics has proven to be very useful for establishing boundary limits
for physical processes, Landauer principle has been a subject of some debate.
Despite the theoretical controversy and fundamental importance of Landauer
erasure in information technology, this phenomenon has not been experimentally
explored using any practical physical implementation for digital information.
Here, we report an investigation of the thermodynamic limits of the memory
erasure process using nanoscale magnetic memory bits, by far the most
ubiquitous digital storage technology today. Through sensitive, temperature
dependent magnetometry measurements, we observed that the amount of dissipated
energy is consistent with the Landauer limit during an adiabatic erasure
process in nanoscale, single domain magnetic thin film islands. This result
confirms the connection between information thermodynamics and physical systems
and also provides a foundation for the development of practical information
processing technologies that approach the fundamental limit of energy
dissipation.
