Berndt Mueller

Duke University, October 18, 12:00 pm

Towards entanglement and thermalization in QCD

The entanglement entropy of a small subsystem of an isolated interacting quantum system indicate whether the subsystem can be interpreted as a “thermal” system. This property is conjectured to underpin the thermal model that has been so successful in describing the final state of relativistic heavy ion collisions. Here we report studies of the entanglement entropy of Hamiltonian SU(2) lattice gauge theory in 2+1 dimensions on linear plaquette chains as a toy model for QCD. We find that the entanglement entropies of both ground and excited states follow Page curves and the transition from the area law for the ground state to the volume law for highly excited states as a function of subsystem size is governed by a universal crossover function. Quantum many-body scars in the middle of the spectrum, which are present in the electric flux truncated Hilbert space, where the gauge theory can be mapped onto an Ising model, disappear when higher electric field representations are included in the Hilbert space basis. This suggests that small subsystems in the continuum SU(2) gauge theory truly behaves as “thermal” systems.