10,009 research outputs found
Remote information concentration using a bound entangled state
Remote information concentration, the reverse process of quantum telecloning,
is presented. In this scheme, quantum information originally from a single
qubit, but now distributed into three spatially separated qubits, is remotely
concentrated back to a single qubit via an initially shared entangled state
without performing any global operations. This entangled state is an unlockable
bound entangled state and we analyze its properties.Comment: 4 pages, 2 figure
Remote Preparation and Distribution of Bipartite Entangled States
We prove a powerful theorem for tripartite remote entanglement distribution
protocols that establishes an upper bound on the amount of entanglement of
formation that can be created between two single-qubit nodes of a quantum
network. Our theorem also provides an operational interpretation of concurrence
as a type of entanglement capacity.Comment: 5 pages, to appear in the Physical Review Letter
A classical analogue of entanglement
We show that quantum entanglement has a very close classical analogue, namely
secret classical correlations. The fundamental analogy stems from the behavior
of quantum entanglement under local operations and classical communication and
the behavior of secret correlations under local operations and public
communication. A large number of derived analogies follow. In particular
teleportation is analogous to the one-time-pad, the concept of ``pure state''
exists in the classical domain, entanglement concentration and dilution are
essentially classical secrecy protocols, and single copy entanglement
manipulations have such a close classical analog that the majorization results
are reproduced in the classical setting. This analogy allows one to import
questions from the quantum domain into the classical one, and vice-versa,
helping to get a better understanding of both. Also, by identifying classical
aspects of quantum entanglement it allows one to identify those aspects of
entanglement which are uniquely quantum mechanical.Comment: 13 pages, references update
Remote transfer of Gaussian quantum discord
Quantum discord quantifies quantum correlation between quantum systems, which
has potential application in quantum information processing. In this paper, we
propose a scheme realizing the remote transfer of Gaussian quantum discord, in
which another quantum discordant state or an Einstein-Podolsky-Rosen entangled
state serves as ancillary state. The calculation shows that two independent
optical modes that without direct interaction become quantum correlated after
the transfer. The output Gaussian quantum discord can be higher than the
initial Gaussian quantum discord when optimal gain of the classical channel and
the ancillary state are chosen. The physical reason for this result comes from
the fact that the quantum discord of an asymmetric Gaussian quantum discordant
state can be higher than that of a symmetric one. The presented scheme has
potential application in quantum information network
Family of Concurrence Monotones and its Applications
We extend the definition of concurrence into a family of entanglement
monotones, which we call concurrence monotones. We discuss their properties and
advantages as computational manageable measures of entanglement, and show that
for pure bipartite states all measures of entanglement can be written as
functions of the concurrence monotones. We then show that the concurrence
monotones provide bounds on quantum information tasks. As an example, we
discuss their applications to remote entanglement distributions (RED) such as
entanglement swapping and remote preparation of bipartite entangled states
(RPBES). We prove a powerful theorem which states what kind of (possibly mixed)
bipartite states or distributions of bipartite states can not be remotely
prepared. The theorem establishes an upper bound on the amount of
-concurrence (one member in the concurrence family) that can be created
between two single-qudit nodes of quantum networks by means of tripartite RED.
For pure bipartite states the bound on the -concurrence can always be
saturated by RPBES.Comment: 8 page
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