Forum de Physique Statistique à l'École Normale Supérieure

Next seminars

15 April, 11h,

Salle Borel, 29 rue d'Ulm, 2nd floor

Sarah Loos (Max Planck)

Moving with minimum effort - Optimal control at the microscale

The controlled manipulation of microscopic systems far from equilibrium is a central theoretical and experimental challenge, with direct relevance to nanomachines, soft microrobotics, and biological molecular systems. At these scales, thermal fluctuations and friction dominate, motivating control strategies that not only steer system dynamics but also minimize energetic costs, as formalized within stochastic thermodynamics.

In this talk, I will discuss recent advances in the thermodynamically optimal control of small-scale systems, which establish fundamental bounds on what processes are realizable for a given energy budget. I will show that even seemingly simple tasks—such as transporting individual particles by harmonic traps—give rise to nontrivial optimal control protocols when performed in realistic fluid environments. I will discuss the impact of environmental memory [1-3], intrinsic activity [4], and particle–particle interactions on optimal control strategies, and discuss how these effects qualitatively alter optimal trajectories and energetic costs.

[1] S. A.M. Loos, S. Monter, F. Ginot, and C. Bechinger, PRX 14, 021032 (2024).

[2] D. Venturelli, S. A. M. Loos, B. Walter, E. Roldan, and A. Gambassi, EPL, 146 27001 (2024).

[3] S. Monter, S. A.M. Loos, and C. Bechinger, PNAS 122, e2510654122 (2025).

[4] R. Garcia-Millan, J. Schüttler, M. E. Cates, and S. A.M. Loos, PRL 135, 088301 (2025).

Upcoming seminars

6 May, Victor Barizien 

13 May, Nicolas Sourlas

17 June, Victor Godet