# Entropy change relation to the number of lost bits

Can we use entropy change value to define the (perhaps fractional) number of bits of information that are lost by and, or, xor gates?

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"these entropy changes" What entropy changes are you referring to? My guess is you're referring to adiabatic, isothermal etc. I don't see why energy entropy should be related to computing entropy so directly. Also, you might be interested in en.wikipedia.org/wiki/Entropy_(computing) –  raindrop Feb 25 '13 at 20:40
I am sorry for that error –  abcdefg Feb 25 '13 at 20:45
Possible duplicate: v1 of this Phys.SE post. –  Qmechanic Feb 25 '13 at 20:48
I have simple logic gates(and, or, xor). I want to calculate the entropy change due to this gates. Say "or" gate. we have 2 inputs(2 bits 0 or 1) and 1 output. This gate is not reversible, if we know the output, we cannot guess the input bits. We have computed entropy somehow, how to find the number of lost bits –  abcdefg Feb 25 '13 at 20:49
@Raindrop Surprisingly, the information and thermodynamic entropies associated with the erasure of the bit are deeply related: see Bennett's seminal work, the Thermodynamics of Computation. –  Mark Mitchison Feb 25 '13 at 21:45