Erasing a bit of information generates 3 x 10-21 joules of heat. A thermodynamic limit to low power computing.

In 1961, Rolf Landauer posited that the act of erasing a bit of information gives off an amount of heat related to the temperature and Boltzmann’s constant—a total of 3 x 10-21 joules at room temperature.

Eric Lutz, of the University of Augsburg set out to demonstrate Landauer’s limit by building a memory consisting of a single particle that could be in either of two wells of potential energy.

Lutz and his colleagues built their system using a 2 micrometer-wide glass bead in water as the particle and created the potential wells using optical tweezers, a laser system that holds particles in place at the laser’s focal point.

Erasing the bit involves first manipulating the laser to lower the barrier between the wells and then reestablishing the potential barrier.

Measurement of the tiny amount of heat was derived by closely following the bead’s trajectory as the bit is erased.

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