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Entropy is measured in J/K or in J/K/mol. What is the smallest value ever measured in an experiment? Google Scholar does not seem to help.

In other words, how good are scientists at measuring small entropy values?

EDIT: I found this paper containing some quite small measured entropy values at low temperature, in Table 8: D. R. Smith and F. Fickett, Low-temperature properties of silver, Journal of Research of the National Institute of Standards and Technology volume 100, page 119 (1995).

EDIT2: The answer below refers to a measurement that gave around 1000 k.

Can quantized transport experiments at ow temperature yield smaller values?

KlausK
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1 Answers1

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Olf et. al. Nature Physics 2015 (arxiv version) generate a very low entropy Bose-Einstein condensate (BEC) of Rb atoms. They claim an entropy of $S/N = 0.001\text{ } k_B$ where $S$ is the total entropy and $N$ is the number of particles in the BEC. It seems $N \approx 10^6$.

This was back in 2015. At the time I remember conversations about "is this the lowest entropy ever acheived" but I wasn't really involved so I don't remember the details. Likely lower entropies have been realized and measured in the field of ultracold atomic physics. Likely in Fermi quantum gas microscopes which rely on very low entropy to realize novel quantum phases. You may be able to get your answer by researching review articles on quantum gas microscopes and things like anti-ferromagnetism in quantum gas microscopes.

There may be physical systems with lower entropy than ultracold atomic ensembles but I'm not personally aware of them.

Jagerber48
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