wikipedia | Landauer's principle, first argued in 1961[1] by Rolf Landauer of IBM, is a physical principle pertaining to the lower theoretical limit of energy consumption of computation. It holds that "any logically irreversible manipulation of information, such as the erasure of a bit or the merging of two computation paths, must be accompanied by a corresponding entropy increase in non-information-bearing degrees of freedom of the information-processing apparatus or its environment". (Bennett 2003)[2]
Landauer's principle asserts that there is a minimum possible amount of energy required to erase one bit of information, known as the Landauer limit:
- kT ln 2,
where k is the Boltzmann constant (approximately 1.38×10−23 J/K), T is the temperature of the circuit in kelvins, and ln 2 is the natural logarithm of 2 (approximately 0.69315).
Another way of phrasing Landauer's principle is that if an observer loses information about a physical system, the observer loses the ability to extract work from that system.
At 20 °C (room temperature, or 293.15 K), the Landauer limit represents an energy of approximately 0.0172 eV, or 2.75 zJ. Theoretically, room‑temperature computer memory operating at the Landauer limit could be changed at a rate of one billion bits per second with only 2.85 trillionths of a watt of power being expended in the memory media. Modern computers use millions of times as much energy.[3][4][5]
If no information is erased, computation may in principle be achieved which is thermodynamically reversible, and require no release of heat. This has led to considerable interest in the study of reversible computing.
Recently, physical experiments have tested Landauer's principle and confirmed its predictions
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