Currently laser cooling schemes are fundamentally based on the weak coupling regime. This requirement sets the trap frequency as an upper bound to the cooling rate. In this work we present a numerical study that shows the feasibility of cooling in th
e strong coupling regime which then allows cooling rates that are faster than the trap frequency with state of the art experimental parameters. The scheme we present can work for trapped atoms or ions as well as mechanical oscillators. It can also cool medium size ions chains close to the ground state.
We investigate the entanglement between two separated segments in the vacuum state of a free 1D Klein-Gordon field, where explicit computations are performed in the continuum limit of the linear harmonic chain. We show that the entanglement, which we
measure by the logarithmic negativity, is finite with no further need for renormalization. We find that the quantum correlations decay much faster than the classical correlations as in the critical limit long range entanglement decays exponentially for separations larger than the size of the segments. As the segments become closer to each other the entanglement diverges as a power law. The noncritical regime manifests richer behavior, as the entanglement depends both on the size of the segments and on their separation. In correspondence with the von Neumann entropy long-range entanglement also distinguishes critical from noncritical systems.
