Complexity transition in the Dicke model of light-matter interaction
When quantum light-matter systems abruptly shift how they behave
Physicists discovered that tweaking how strongly light couples to atoms can trigger a sudden, sharp change in how chaotically a quantum system evolves—visible through a mathematical measure called Krylov complexity. The transition marks the boundary between two fundamentally different types of quantum behavior, where the system switches from being orderly and confined to becoming wild and spreading.
Understanding when and how quantum systems undergo these sharp transitions is crucial for controlling quantum computers and optical devices, where tiny changes in coupling strength could unexpectedly alter performance. This framework gives physicists a new tool to predict and detect phase transitions in quantum dynamics that don't show up in traditional equilibrium measurements, opening doors to better design of quantum technologies and detection of chaotic behavior in exotic quantum states.