10 research outputs found
Separable states to distribute entanglement
It was shown that two distant particles can be entangled by sending a third
particle never entangled with the other two [T. S. Cubitt et al., Phys. Rev.
Lett. 91, 037902 (2003)]. In this paper, we investigate a class of three-qubit
separable states to distribute entanglement by the same way, and calculate the
maximal amount of entanglement which two particles of separable states in the
class can have after applying the way.Comment: 4 pages, no figures, Revised argumen
Local channels preserving maximal entanglement or Schmidt number
Maximal entanglement and Schmidt number play an important role in various
quantum information tasks. In this paper, it is shown that a local channel
preserves maximal entanglement state(MES) or preserves pure states with Schmidt
number ( is a fixed integer) if and only if it is a local unitary
operation.Comment: 10 page
Sudden switch of generalized Lieb-Robinson velocity in a transverse field Ising spin chain
The Lieb-Robinson theorem states that the speed at which the correlations
between two distant nodes in a spin network can be built through local
interactions has an upper bound, which is called the Lieb-Robinson velocity.
Our central aim is to demonstrate how to observe the Lieb-Robinson velocity in
an Ising spin chain with a strong transverse field. We adopt and compare four
correlation measures for characterizing different types of correlations, which
include correlation function, mutual information, quantum discord, and
entanglement of formation. We prove that one of correlation functions shows a
special behavior depending on the parity of the spin number. All the
information-theoretical correlation measures demonstrate the existence of the
Lieb-Robinson velocity. In particular, we find that there is a sudden switch of
the Lieb-Robinson speed with the increasing of the number of spin