Introduction to Quantum Physics and Information Processing

Computation Models and Computational Complexity 111

in the box is given by k

B

ln 2, where k

B

, the Boltzmann constant

1

, is a pro-

portionality factor. If the process of erasure is carried out at a constant tem-

perature T then the energy dissipated in this process equals the work done in

pushing the piston, which is k

B

T ln 2. This is the least amount of energy that

is lost per bit when one performs an irreversible computation.

While there has been considerable debate in the literature regarding Lan-

dauer’s principle, recently there appears to be experimental confirmation of

the heat dissipated when a bit of information is erased. [12].

6.3.1 Classical ...