理論セミナー(Dr. N. Watamura)
We have studied the time evolution of Entanglement Entropy (EE) in 4 dimensional (space time) Maxwell theory. We perform a local excitation by acting with a local operator on the vacuum state. An inserted local gauge invariant operator changes the structure of entanglement, and so the EE. We take the half of the total space as the subspace, and evaluate the increase of (Renyi) EE from the one of the vacuum state by using the replica method. The increase of the (Renyi) EE converges to a value as t goes to infinity (late time limit). We showed that in this limit, the increase of Renyi EE can be interpreted in terms of quasi-particles, but descrived with a non-trivial algebra reflecting the specialty of gauge theory. We found a way of determining this algebra from the propagator, and confirmed that this works also in the case for free scalar field theory and 6d Maxwell Theory.
・Masahiro Nozaki, Naoki Watamura "Quantum Entanglement of Locally Excited States in Maxwell Theory" arXiv:1606.07076 [hep-th].