Quantum measurement and the first law of thermodynamics: the energy cost of measurement is the work value of the acquired information

TL;DR

This paper investigates the fundamental energy costs of quantum measurement, clarifying that real measurement devices incur costs similar to heat engines, and that measurement's energy expense is tied to the work value of information.

Contribution

It clarifies the true energy cost of quantum measurement, showing that real devices always pay a cost equivalent to a heat engine, resolving apparent contradictions in Maxwell's demon scenarios.

Findings

Real measurement devices require energy costs similar to heat engines.

Measurement cost is linked to the work value of acquired information.

Zero-temperature reservoirs would eliminate measurement energy costs.

Abstract

The energy cost of measurement is an interesting fundamental question, and may have profound implications for quantum technologies. In the context of Maxwell's demon, it is often stated that measurement has no minimum energy cost, while information has a work value, even though these statements can appear contradictory. However, as we elucidate, these statements do no refer to the cost paid by the measuring device. Here we show that it is only when a measuring device has access to a zero temperature reservoir - that is, never - that the measurement requires no energy. All real measuring devices pay the cost that a heat engine pays to obtain the work value of the information they acquire.