Quantum measurements can slow information spread from fast to slow?

Quantum systems under frequent observation tend to freeze up — the quantum Zeno effect. Here, researchers show that monitoring a chain of quantum spins causes a sharp transition: domain walls spread at constant speed when measurements are rare, but slow to a diffusive crawl at high measurement rates. Crucially, unlike related entanglement transitions that require impractical exponential postselection of measurement outcomes, this ballistic-to-diffusive shift is directly observable, making it a rare experimentally accessible window into measurement-driven quantum phase transitions.