Entangled spins and ghost-spins

Entangled spins and ghost-spins

Blog Article

We study patterns of quantum entanglement in systems of spins and ghost-spins regarding them as bolia outlet gent simple quantum mechanical toy models for theories containing negative norm states.We define a single ghost-spin as in [20] as a 2-state spin variable with an indefinite inner product in the state space.We find that whenever the spin sector is disentangled from the ghost-spin sector (both of which could be entangled within themselves), the reduced density matrix obtained by tracing over all the ghost-spins gives rise to positive entanglement entropy for positive norm states, while negative norm states have an entanglement entropy with a negative real part and a constant imaginary part.However when the spins are entangled with the ghost-spins, there are new entanglement patterns in general.

For systems where the number of ghost-spins is even, it is possible to find subsectors of the Hilbert space where positive norm states always lead to positive entanglement entropy after tracing over the ghost-spins.With an odd eeboo coupons number of ghost-spins however, we find that there always exist positive norm states with negative real part for entanglement entropy after tracing over the ghost-spins.