87 research outputs found
Advances in Quantum Teleportation
Quantum teleportation is one of the most important protocols in quantum
information. By exploiting the physical resource of entanglement, quantum
teleportation serves as a key primitive in a variety of quantum information
tasks and represents an important building block for quantum technologies, with
a pivotal role in the continuing progress of quantum communication, quantum
computing and quantum networks. Here we review the basic theoretical ideas
behind quantum teleportation and its variant protocols. We focus on the main
experiments, together with the technical advantages and disadvantages
associated with the use of the various technologies, from photonic qubits and
optical modes to atomic ensembles, trapped atoms, and solid-state systems.
Analysing the current state-of-the-art, we finish by discussing open issues,
challenges and potential future implementations.Comment: Nature Photonics Review. Comments are welcome. This is a
slightly-expanded arXiv version (14 pages, 5 figure, 1 table
Photonic entanglement as a resource in quantum computation and quantum communication
Entanglement is an essential resource in current experimental implementations
for quantum information processing. We review a class of experiments exploiting
photonic entanglement, ranging from one-way quantum computing over quantum
communication complexity to long-distance quantum communication. We then
propose a set of feasible experiments that will underline the advantages of
photonic entanglement for quantum information processing.Comment: 33 pages, 4 figures, OSA styl
Recursive quantum repeater networks
Internet-scale quantum repeater networks will be heterogeneous in physical
technology, repeater functionality, and management. The classical control
necessary to use the network will therefore face similar issues as Internet
data transmission. Many scalability and management problems that arose during
the development of the Internet might have been solved in a more uniform
fashion, improving flexibility and reducing redundant engineering effort.
Quantum repeater network development is currently at the stage where we risk
similar duplication when separate systems are combined. We propose a unifying
framework that can be used with all existing repeater designs. We introduce the
notion of a Quantum Recursive Network Architecture, developed from the emerging
classical concept of 'recursive networks', extending recursive mechanisms from
a focus on data forwarding to a more general distributed computing request
framework. Recursion abstracts independent transit networks as single relay
nodes, unifies software layering, and virtualizes the addresses of resources to
improve information hiding and resource management. Our architecture is useful
for building arbitrary distributed states, including fundamental distributed
states such as Bell pairs and GHZ, W, and cluster states.Comment: 14 page
Philosophical Aspects of Quantum Information Theory
Quantum information theory represents a rich subject of discussion for those
interested in the philosphical and foundational issues surrounding quantum
mechanics for a simple reason: one can cast its central concerns in terms of a
long-familiar question: How does the quantum world differ from the classical
one? Moreover, deployment of the concepts of information and computation in
novel contexts hints at new (or better) means of understanding quantum
mechanics, and perhaps even invites re-assessment of traditional material
conceptions of the basic nature of the physical world. In this paper I review
some of these philosophical aspects of quantum information theory, begining
with an elementary survey of the theory, seeking to highlight some of the
principles and heuristics involved. We move on to a discussion of the nature
and definition of quantum information and deploy the findings in discussing the
puzzles surrounding teleportation. The final two sections discuss,
respectively, what one might learn from the development of quantum computation
(both about the nature of quantum systems and about the nature of computation)
and consider the impact of quantum information theory on the traditional
foundational questions of quantum mechanics (treating of the views of
Zeilinger, Bub and Fuchs, amongst others).Comment: LaTeX; 55pp; 3 figs. Forthcoming in Rickles (ed.) The Ashgate
Companion to the New Philosophy of Physic
Quantum entanglement
All our former experience with application of quantum theory seems to say:
{\it what is predicted by quantum formalism must occur in laboratory}. But the
essence of quantum formalism - entanglement, recognized by Einstein, Podolsky,
Rosen and Schr\"odinger - waited over 70 years to enter to laboratories as a
new resource as real as energy.
This holistic property of compound quantum systems, which involves
nonclassical correlations between subsystems, is a potential for many quantum
processes, including ``canonical'' ones: quantum cryptography, quantum
teleportation and dense coding. However, it appeared that this new resource is
very complex and difficult to detect. Being usually fragile to environment, it
is robust against conceptual and mathematical tools, the task of which is to
decipher its rich structure.
This article reviews basic aspects of entanglement including its
characterization, detection, distillation and quantifying. In particular, the
authors discuss various manifestations of entanglement via Bell inequalities,
entropic inequalities, entanglement witnesses, quantum cryptography and point
out some interrelations. They also discuss a basic role of entanglement in
quantum communication within distant labs paradigm and stress some
peculiarities such as irreversibility of entanglement manipulations including
its extremal form - bound entanglement phenomenon. A basic role of entanglement
witnesses in detection of entanglement is emphasized.Comment: 110 pages, 3 figures, ReVTex4, Improved (slightly extended)
presentation, updated references, minor changes, submitted to Rev. Mod. Phys
Quantum nonlocality, cryptography and complexity
Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal
Quantum Teamwork for Unconditional Multiparty Communication with Gaussian States
We demonstrate the capability of continuous variable Gaussian states to
communicate multipartite quantum information. A quantum teamwork protocol is
presented according to which an arbitrary possibly entangled multimode state
can be faithfully teleported between two teams each comprising many cooperative
users. We prove that N-mode Gaussian weighted graph states exist for arbitrary
N, that enable unconditional quantum teamwork implementations for any
arrangement of the teams. These perfect continuous variable maximally
multipartite entangled resources are typical among pure Gaussian states and are
unaffected by the entanglement frustration occurring in multiqubit states.Comment: 4+2 pages, 2 figures. Published version with appendi
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