Stochastic Thermodynamics: from active molecular pumps to chimera states

NONTECHNICAL SUMMARY

This award supports theoretical research and education to advance understanding of nonequilibrium systems using and further developing stochastic thermodynamics. Stochastic thermodynamics is an emerging theoretical framework that generalizes standard thermodynamics to small nonequilibrium systems. Examples of such systems in experiments include colloids, quantum dots and molecular biochemical systems.

The research group will investigate four relevant topics in stochastic thermodynamics. The first topic is focused on the connection between stochastic thermodynamics and Chimera states, which are two prominent lines of research in statistical physics that remain disconnected. A Chimera state is a phase of interacting oscillators where only part of the oscillators synchronize.

The PI will use a model to establish a connection between stochastic thermodynamics and Chimera states, which will enable the role of energy dissipation in Chimera states to be analyzed. The second topic is an open problem in stochastic thermodynamics. The thermodynamic uncertainty is a prominent relation that establishes the minimal universal cost of precision in stochastic thermodynamics.

This relation has been found to be violated for the so-called underdamped Langevin dynamics. The PI aims to find bounds on fluctuations for underdamped dynamics similar to the thermodynamic uncertainty relation. The remaining two topics are on active systems, systems with hidden dissipative degrees of freedom such as living systems.

The research group will investigate the emergence of net motion in a stochastic molecular system in an active medium and heat engines in an active medium. Students will be trained, and the PI will engage in international collaboration. TECHNICAL SUMMARY

This award supports theoretical research and education to advance understanding of nonequilibrium systems using and developing stochastic thermodynamics. Stochastic thermodynamics is an emerging theoretical framework in nonequilibrium statistical physics. It has contributed to the understanding of small nonequilibrium systems through the discovery of relatively novel universal relations such as the fluctuation theorem and the thermodynamic uncertainty relations.

Examples of such systems include colloids, quantum dots and molecular biochemical systems. The research group will investigate four relevant topics in stochastic thermodynamics: 1.) A Chimera state is a phase of interacting oscillators for which part of the oscillators synchronize and the other part does not. Considerable work has been done on Chimera states; however, the connection between Chimera states and stochastic thermodynamics remains unexplored.

The research group will connect Chimera states with stochastic thermodynamics using a model the PI introduced. 2.) The thermodynamic uncertainty relation has been found to be violated for underdamped Langevin dynamics. The team aims to find bounds on current fluctuations for underdamped dynamics based on a discretization of underdamped dynamics. The last topic is an important continuation of the recent work of the research team on active heat engines.

The research team will develop a linear response theory for active heat engines. 3.) Stochastic pumps are systems that generate unidirectional motion in the form of a net current with a time-periodic protocol. Their theoretical research is inspired by experiments with artificial molecular machines, which are often operated with a time-periodic protocol.

A goal in this area of research is to build artificial molecules capable of performing a function inside a living organism, that is, in an active medium. The PI will investigate active stochastic pumps, an area that has been largely unexplored. In particular, the team will determine the necessary conditions for the emergence of a flux in active stochastic pumps. 4.) The PI will continue working on active heat engines. The research team will develop a linear response theory for active heat engines.

Students will be trained, and the PI will engage in international collaboration.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.