3 research outputs found
The fully entangled fraction as an inclusive measure of entanglement applications
Characterizing entanglement in all but the simplest case of a two qubit pure
state is a hard problem, even understanding the relevant experimental
quantities that are related to entanglement is difficult. It may not be
necessary, however, to quantify the entanglement of a state in order to
quantify the quantum information processing significance of a state. It is
known that the fully entangled fraction has a direct relationship to the
fidelity of teleportation maximized under the actions of local unitary
operations. In the case of two qubits we point out that the fully entangled
fraction can also be related to the fidelities, maximized under the actions of
local unitary operations, of other important quantum information tasks such as
dense coding, entanglement swapping and quantum cryptography in such a way as
to provide an inclusive measure of these entanglement applications. For two
qubit systems the fully entangled fraction has a simple known closed-form
expression and we establish lower and upper bounds of this quantity with the
concurrence. This approach is readily extendable to more complicated systems.Comment: 14 pages, 2 figures, accepted in Physics Letters