File Transmission as a Carnot Machine

Since a file is a transmitted sequence of energetic pulses, we can calculate its, energy, entropy, and temperature. From Planck's blackbody equation, it argues that a single-mode light pulse, with a large number of photons, carries one entropy unit. Similarly, an empty radiation mode carries no entropy. To calculate the entropy of the sequence of pulses, it is first necessary to calculate the entropy of a single, single-mode coherent pulse. In this case, the calculated entropy that a coded sequence of light pulses is carrying is simply the Gibbs mixing entropy, which is the logical Shannon information. This approach is supported by a demonstration that the transmission and the amplification of a digital information file, in an optical fiber, is a classic Carnot machine comprising of two isothermals and two adiabatic. Therefore, it is suggested that information is entropy. The Carnot efficiency of an amplifier can be tested experimentally. Calorimetric experiments of this kind require careful photon counting; nevertheless, they are possible in contemporary technology. This study suggests that the second law is applicable in the classical limit to informatics.