Bound entanglement and teleportation for arbitrary bipartite systems

Mary M. Cola, Matteo G. A. Paris

Jiao Fan, Hui Zhao

We construct bound entangled states that are entangled but from which no entanglement can be distilled if all parties are allowed only by performing local operations and classical communications. Moreover, as applications, a detailed example is presented. This example can illuminate that the fidelity of transmission using a bound entangled state is not bigger than a classical scheme.

Hui Zhao, Sha Guo

N. Gigena, R. Rossignoli

We discuss the relation between fermion entanglement and bipartite entanglement. We first show that an exact correspondence between them arises when the states are constrained to have a definite local number parity. Moreover, for arbitrary states in a four-dimensional single-particle Hilbert space, the fermion entanglement is shown to measure the entanglement between two distinguishable qubits defined by a suitable partition of this space. Such entanglement can be used as a resource for tasks like quantum teleportation. On the other hand, this fermionic entanglement provides a lower bound to the entanglement of an arbitrary bipartition, although in this case the local states involved will generally have different number parities. Finally, the fermionic implementation of the teleportation and superdense coding protocols based on qubits with odd and even number parity is discussed, together with the role of the previous types of entanglement.

Zhou, Jian JIAN, Yang Yang +3 more

Guifré Vidal, Reinhard F. Werner

We present a measure of entanglement that can be computed effectively for any mixed state of an arbitrary bipartite system. We show that it does not increase under local manipulations of the system, and use it to obtain a bound on the teleportation capacity and on the distillable entanglement of mixed states.