Physics Practical Magic

If you want a crystal to grow fast, focus on the edges—but if you want it to grow smart, you've gotta start at the corners.

March 20, 2026

Original Paper

Optimal strategies for controlled growth in metastable Kawasaki dynamics

Simone Baldassarri, Maike C. de Jongh

arXiv · 2603.18903

The Takeaway

Using the physics of atomic movement (Kawasaki dynamics), researchers discovered a fundamental conflict in material growth. They proved that speed and energy cost require completely different geometric patterns, meaning we must choose between rapid expansion and molecular stability when building new materials.

From the abstract

In this paper, we develop a Markov decision process (MDP) formulation for the low--temperature metastable Ising model evolving according to Kawasaki dynamics in a finite box of the two--dimensional square lattice. We analyze how an external controller can guide the system to the all--occupied state by appropriately adding and moving particles at specified moments in time. To this end, we construct a reduced MDP on a constrained family of configurations having a single cluster, a regime where par