Frustration-induced emergent Hilbert space fragmentation

Understand

Although most quantum systems thermalize locally on short time scales independent of initial conditions, recent developments have shown this is not always the case.

• Lattice geometry and quantum mechanics can conspire to produce constrained quantum dynamics and associated glassy behavior, a phenomenon that falls outside the rubric of the eigenstate thermalization hypothesis.
• Constraints "fragment" the many-body Hilbert space due to which some states remain insulated from others and the system fails to attain thermal equilibrium.
• Such fragmentation is a hallmark of geometrically frustrated magnets with low-energy "icelike manifolds" exhibiting a broad range of relaxation times for different initial states.