1 research outputs found
Entanglement at the quantum phase transition in a harmonic lattice
The entanglement properties of the phase transition in a two dimensional
harmonic lattice, similar to the one observed in recent ion trap experiments,
are discussed both, for finite number of particles and thermodynamical limit.
We show that for the ground state at the critical value of the trapping
potential two entanglement measures, the negativity between two neighbouring
sites and the block entropy for blocks of size 1, 2 and 3, change abruptly.
Entanglement thus indicates quantum phase transitions in general; not only in
the finite dimensional case considered in [Phys. Rev. Lett. {\bf 93}, 250404
(2004)]. Finally, we consider the thermal state and compare its exact
entanglement with a temperature entanglement witness introduced in [Phys. Rev.
A {\bf 77} 062102 (2008)].Comment: extended published versio