Kwon Euijoon, Park Jong-Min, Lee Jae Sung, Baek Yongjoo
Department of Physics and Astronomy & Center for Theoretical Physics, <a href="https://ror.org/04h9pn542">Seoul National University</a>, Seoul 08826, Republic of Korea.
School of Physics, <a href="https://ror.org/041hz9568">Korea Institute for Advanced Study</a>, Seoul 02455, Republic of Korea.
Phys Rev E. 2024 Oct;110(4-1):044131. doi: 10.1103/PhysRevE.110.044131.
Recent years have witnessed a surge of discoveries in the studies of thermodynamic inequalities: the thermodynamic uncertainty relation (TUR) and the entropic bound (EB) provide a lower bound on the entropy production (EP) in terms of nonequilibrium currents; the classical speed limit (CSL) expresses the lower bound on the EP using the geometry of probability distributions; the power-efficiency (PE) tradeoff dictates the maximum power achievable for a heat engine given the level of its thermal efficiency. In this study, we show that there exists a unified hierarchical structure encompassing all of these bounds, with the fundamental inequality given by an extension of the TUR (XTUR) that incorporates the most general range of currentlike and state-dependent observables. By selecting more specific observables, the TUR and the EB follow from the XTUR, and the CSL and the PE tradeoff follow from the EB. Our derivations cover both Langevin and Markov jump systems, with the first proof of the EB for the Markov jump systems and a more generalized form of the CSL. We also present concrete examples of the EB for the Markov jump systems and the generalized CSL.