What it is
Thermodynamics establishes that information acquired through measurement can be converted into work, as in Maxwell's demon and Szilard engines, but most experimental information engines implicitly assume Markovian environments, in which information exchanged with the surroundings is irreversibly lost. Many physical systems instead have environmental memory: hidden degrees of freedom keep correlations with the system's history and make its dynamics non-Markovian, and whether such concealed memory can be harnessed as a thermodynamic resource had remained an open question. Using time-resolved measurements on an optically trapped Brownian particle in equilibrium, the authors implemented a time-delayed double-measurement protocol that retrieves information through backflow from hidden degrees of freedom of the surrounding bath. They show that this information backflow alters the particle's relaxation dynamics, can be quantified independently of initial-state effects and, when appropriately exploited, enhances work extraction, and they identify regimes in which the extracted work exceeds the energy stored in the observable degree of freedom alone. The authors conclude that environmental memory is an experimentally accessible thermodynamic resource, and that non-Markovian dynamics can be explored systematically to improve information engines operating in time-correlated environments.
Why it matters
Using hidden memory in a trapped particle's bath, an information engine in some regimes extracted more work than the energy stored in the observed degree of freedom alone. Maxwell's demon and Szilard engines show that information gained by measurement can become work, but experimental information engines have mostly assumed environments in which information exchanged with the surroundings is irreversibly lost. Here a time-delayed double measurement on an optically trapped Brownian particle in equilibrium recovered information flowing back from hidden degrees of freedom of the bath; this backflow altered the particle's relaxation dynamics and, when appropriately exploited, enhanced work extraction, which the authors present as establishing environmental memory as an experimentally accessible thermodynamic resource.
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Filed underAdvanced Thermodynamics and Statistical Mechanics, Advanced Thermodynamic Systems and Engines, stochastic dynamics and bifurcation
