Crooks Fluctuation Theorem for Single Polymer Dynamics in Time-Dependent Flows: Understanding Viscoelastic Hysteresis

Nonequilibrium work relations have fundamentally advanced our understanding of molecular processes. In recent years, fluctuation theorems have been extensively applied to understand transitions between equilibrium steady-states, commonly described by simple control parameters such as molecular extension of a protein or polymer chain stretched by an external force in a quiescent fluid. Despite recent progress, far less is understood regarding the application of fluctuation theorems to processes involving nonequilibrium steady-states such as those described by polymer stretching dynamics in nonequilibrium fluid flows. In this work, we apply the Crooks fluctuation theorem to understand the nonequilibrium thermodynamics of dilute polymer solutions in flow. We directly determine the nonequilibrium free energy for single polymer molecules in flow using a combination of single molecule experiments and Brownian dynamics simulations. We further develop a time-dependent extensional flow protocol that allows for probing viscoelastic hysteresis over a wide range of flow strengths. Using this framework, we define quantities that uniquely characterize the coil-stretch transition for polymer chains in flow. Overall, generalized fluctuation theorems provide a powerful framework to understand polymer dynamics under far-from-equilibrium conditions.

Fluctuating relativistic hydrodynamics from Crooks theorem

We use the Crooks fluctuation theorem [1, 2] together with Zubarev hydro- dynamics [3] to develop a bottom-up theory of hydrodynamic fluctuations. We also use thermodynamic uncertainity relations to estimate bottom-up limits to dissipative transport coefficients.

Hot Wired

Two physicists engage in a courteous and exhilarating exchange. Jeremy England argues that descendants of the Crooks fluctuation theorem play, and should play, a role in explaining life’s origin. He is, in his optimism, a nightingale among pigeons. Brian Miller is equally persuaded that these theorems are of little relevance in explaining the origin of life. Pigeons remain well-satisfied.

Flaw in Crooks Fluctuation Theorem

The existence of Crooks fluctuation theorem (even at microscopic level, in a very short time period) is a direct threat to the second law of thermodynamics. In this paper, we will underline the flaw that exists in Crooks fluctuation theorem assumptions, and thus, we will confirm the validity of the second law of thermodynamics at any temperature, pressure, and at any scale (time, and length-scale) in nature. We will validate the Loschmidts paradox, and will show that no physical directional-process can be perfectly-reversible at any non-zero, finite temperature (T>0 K) and pressure (P>0) in nature.

Quantum fluctuation relations

We present here a set of lecture notes on exact fluctuation relations. We prove the Jarzynski equality and the Crooks fluctuation theorem, two paradigmatic examples of classical fluctuation relations. Finally, we consider their quantum versions, and analyze analogies and differences with the classical case.