  Energy transfer and information transmission are two fundamental aspects of
nature. They are seemingly unrelated, while recent findings suggest that a deep
connection between them is to be discovered. This amounts to asking: can we
phrase the processes of transmitting classical bits equivalently as specific
energy-exchanging tasks, thereby uncovering foundational links between them? We
answer this question positively by showing that, for a broad class of classical
communication tasks, transmitting $n$ bits of classical information via quantum
dynamics is equivalent to extracting $n$ units of energy in a thermodynamic
work-extraction task. This finding not only provides an analytical
correspondence between information transmission and energy extraction tasks but
also quantifies classical communication by thermodynamics. In the asymptotic
regime, our results further provide thermodynamic meanings for the well-known
Holevo-Schumacher-Westmoreland Theorem in quantum communication theory.
