Fundamental energy cost for quantum measurement
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Abstract
Measurements and feedback are essential in the control of any device operating at the quantum scale and exploiting the features of quantum physics. As the number of quantum components grows, it becomes imperative to consider the energetic expense of such elementary operations. Here we determine the fundamental energy requirements for physical implementations of any general quantum measurement. We show that the exact costs for projective measurements depend on the outcome probabilities only, causing more severe constraints on error correction and control protocols than previously known. In contrast, energy can be extracted from certain measurement processes even if their outcome is recorded. Our results constitute fundamental physical limitations against which to benchmark implementations of future quantum devices as they grow in complexity.