6,167 research outputs found
âThe Necessary War: Canadians Fighting the Second World War 1939â1943, Volume One (Book Review)â by Tim Cook & âFight to the Finish: Canadians in the Second World War 1944â1945, Volume Two (Book Review)â by Tim Cook
Review of The Necessary War: Canadians Fighting the Second World War 1939â1943, Volume One & Fight to the Finish: Canadians in the Second World War 1944â1945, Volume Two by Tim Cook
Review of Dominion of Race: Rethinking Canadaâs International History by Laura Madokoro, Francine McKenzie and David Meren, eds.
Review of Dominion of Race: Rethinking Canadaâs International History by Laura Madokoro, Francine McKenzie and David Meren, eds
Two Years Below the Horn: Operation Tabarin, Field Science, and Antarctic Sovereignty, 1944â1946 (Book Review) by Andrew Taylor, edited by Daniel Heidt and P. Whitney Lackenbauer
Review of Two Years Below the Horn: Operation Tabarin, Field Science, and Antarctic Sovereignty, 1944â1946 by Andrew Taylor, edited by Daniel Heidt and P. Whitney Lackenbauer
Towards feedback control of entanglement
We provide a model to investigate feedback control of entanglement. It
consists of two distant (two-level) atoms which interact through a radiation
field and becomes entangled. We then show the possibility to stabilize such
entanglement against atomic decay by means of a feedback action.Comment: 6 pages, 4 figure
Optomechanical tailoring of quantum fluctuations
We propose the use of feedback mechanism to control the level of quantum
noise in a radiation field emerging from a pendular Fabry-Perot cavity. It is
based on the possibility to perform quantum nondemolition measurements by means
of optomechanical coupling.Comment: ReVTeX file, 8 pages, 1 Postscript figure. to appear in J. Opt. B:
Quant. Semiclass. Op
Quantum error correction for continuously detected errors
We show that quantum feedback control can be used as a quantum error
correction process for errors induced by weak continuous measurement. In
particular, when the error model is restricted to one, perfectly measured,
error channel per physical qubit, quantum feedback can act to perfectly protect
a stabilizer codespace. Using the stabilizer formalism we derive an explicit
scheme, involving feedback and an additional constant Hamiltonian, to protect
an ()-qubit logical state encoded in physical qubits. This works for
both Poisson (jump) and white-noise (diffusion) measurement processes. In
addition, universal quantum computation is possible in this scheme. As an
example, we show that detected-spontaneous emission error correction with a
driving Hamiltonian can greatly reduce the amount of redundancy required to
protect a state from that which has been previously postulated [e.g., Alber
\emph{et al.}, Phys. Rev. Lett. 86, 4402 (2001)].Comment: 11 pages, 1 figure; minor correction
Entanglement under restricted operations: Analogy to mixed-state entanglement
We show that the classification of bi-partite pure entangled states when
local quantum operations are restricted yields a structure that is analogous in
many respects to that of mixed-state entanglement. Specifically, we develop
this analogy by restricting operations through local superselection rules, and
show that such exotic phenomena as bound entanglement and activation arise
using pure states in this setting. This analogy aids in resolving several
conceptual puzzles in the study of entanglement under restricted operations. In
particular, we demonstrate that several types of quantum optical states that
possess confusing entanglement properties are analogous to bound entangled
states. Also, the classification of pure-state entanglement under restricted
operations can be much simpler than for mixed-state entanglement. For instance,
in the case of local Abelian superselection rules all questions concerning
distillability can be resolved.Comment: 10 pages, 2 figures; published versio
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