1,801 research outputs found
Optimal quantum teleportation with an arbitrary pure state
We derive the maximum fidelity attainable for teleportation using a shared
pair of d-level systems in an arbitrary pure state. This derivation provides a
complete set of necessary and sufficient conditions for optimal teleportation
protocols. We also discuss the information on the teleported particle which is
revealed in course of the protocol using a non-maximally entangled state.Comment: 10 pages, REVTe
Multi-output programmable quantum processor
By combining telecloning and programmable quantum gate array presented by
Nielsen and Chuang [Phys.Rev.Lett. 79 :321(1997)], we propose a programmable
quantum processor which can be programmed to implement restricted set of
operations with several identical data outputs. The outputs are
approximately-transformed versions of input data. The processor successes with
certain probability.Comment: 5 pages and 2 PDF figure
Protocols for entanglement transformations of bipartite pure states
We present a general theoretical framework for both deterministic and
probabilistic entanglement transformations of bipartite pure states achieved
via local operations and classical communication. This framework unifies and
greatly simplifies previous works. A necessary condition for ``pure
contraction'' transformations is given. Finally, constructive protocols to
achieve both probabilistic and deterministic entanglement transformations are
presented.Comment: 7 pages, no figures. Version slightly modified on Physical Review A
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Optimal estimation of quantum dynamics
We construct the optimal strategy for the estimation of an unknown unitary
transformation . This includes, in addition to a convenient
measurement on a probe system, finding which is the best initial state on which
is to act. When , such an optimal strategy can be applied to
estimate simultaneously both the direction and the strength of a magnetic
field, and shows how to use a spin 1/2 particle to transmit information about a
whole coordinate system instead of only a direction in space.Comment: 4 pages, REVTE
Local transformation of mixed states of two qubits to Bell diagonal states
The optimal entanglement manipulation for a single copy of mixed states of
two qubits is to transform it to a Bell diagonal state. In this paper we derive
an explicit form of the local operation that can realize such a transformation.
The result obtained is universal for arbitrary entangled two-qubit states and
it discloses that the corresponding local filter is not unique for density
matrices with rank and can be exclusively determined for that with
and 4. As illustrations, a four-parameters family of mixed states are explored,
the local filter as well as the transformation probability are given
explicitly, which verify the validity of the general result.Comment: 5 pages, to be published in Phys. Rev.
Reversible transformations from pure to mixed states, and the unique measure of information
Transformations from pure to mixed states are usually associated with
information loss and irreversibility. Here, a protocol is demonstrated allowing
one to make these transformations reversible. The pure states are diluted with
a random noise source. Using this protocol one can study optimal
transformations between states, and from this derive the unique measure of
information. This is compared to irreversible transformations where one does
not have access to noise. The ideas presented here shed some light on attempts
to understand entanglement manipulations and the inevitable irreversibility
encountered there where one finds that mixed states can contain "bound
entanglement".Comment: 10 pages, no figures, revtex4, table added, to appear in Phys. Rev.
MicroRNA Profiling and Bioinformatics Target Analysis in Dorsal Hippocampus of Chronically Stressed Rats: Relevance to Depression Pathophysiology
IndexaciĂłn: Scopus.1Laboratory of Neuroplasticity and Neurogenetics, Faculty of Chemical and Pharmaceutical Sciences, Department of Biochemistry and Molecular Biology, Universidad de Chile, Santiago, Chile, 2National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Durham, NC, United States, 3Centro de GenĂłmica y BioinformĂĄtica, Facultad de Ciencias, Universidad Mayor, Santiago, Chile, 4Millennium Institute for Integrative Biology (iBio), FONDAP Center for Genome Regulation, Departamento de GenĂ©tica Molecular y MicrobiologĂa, Pontificia Universidad CatĂłlica de Chile, Santiago, Chile, 5Department of Kinesiology, Faculty of Health Sciences, Universidad CatĂłlica del Maule, Talca, Chile, 6Escuela de QuĂmica y Farmacia, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile.This study was supported by the following grants: FONDECYT 1120528 (JLF), Fondo Central de InvestigaciĂłn, Universidad de Chile ENL025/16 (JLF), ES090079 (JAC). Research in RG and EV laboratories is funded by Instituto Milenio iBio â Iniciativa CientĂfica Milenio MINECON.Studies conducted in rodents subjected to chronic stress and some observations in humans after psychosocial stress, have allowed to establish a link between stress and the susceptibility to many complex diseases, including mood disorders. The studies in rodents have revealed that chronic exposure to stress negatively affects synaptic plasticity by triggering changes in the production of trophic factors, subunit levels of glutamate ionotropic receptors, neuron morphology, and neurogenesis in the adult hippocampus. These modifications may account for the impairment in learning and memory processes observed in chronically stressed animals. It is plausible then, that stress modifies the interplay between signal transduction cascades and gene expression regulation in the hippocampus, therefore leading to altered neuroplasticity and functioning of neural circuits. Considering that miRNAs play an important role in post-transcriptional-regulation of gene expression and participate in several hippocampus-dependent functions; we evaluated the consequences of chronic stress on the expression of miRNAs in dorsal (anterior) portion of the hippocampus, which participates in memory formation in rodents. Here, we show that male rats exposed to daily restraint stress (2.5 h/day) during 7 and 14 days display a differential profile of miRNA levels in dorsal hippocampus and remarkably, we found that some of these miRNAs belong to the miR-379-410 cluster. We confirmed a rise in miR-92a and miR-485 levels after 14 days of stress by qPCR, an effect that was not mimicked by chronic administration of corticosterone (14 days). Our in silico study identified the top-10 biological functions influenced by miR-92a, nine of which were shared with miR-485: Nervous system development and function, Tissue development, Behavior, Embryonic development, Organ development, Organismal development, Organismal survival, Tissue morphology, and Organ morphology. Furthermore, our in silico study provided a landscape of potential miRNA-92a and miR-485 targets, along with relevant canonical pathways related to axonal guidance signaling and cAMP signaling, which may influence the functioning of several neuroplastic substrates in dorsal hippocampus. Additionally, the combined effect of miR-92a and miR-485 on transcription factors, along with histone-modifying enzymes, may have a functional relevance by producing changes in gene regulatory networks that modify the neuroplastic capacity of the adult dorsal hippocampus under stress. © 2018 Muñoz-Llanos, GarcĂa-PĂ©rez, Xu, Tejos-Bravo, Vidal, Moyano, GutiĂ©rrez, Aguayo, Pacheco, GarcĂa-Rojo, Aliaga, Rojas, Cidlowski and Fiedler.https://www.frontiersin.org/articles/10.3389/fnmol.2018.00251/ful
An entanglement monotone derived from Grover's algorithm
This paper demonstrates that how well a state performs as an input to
Grover's search algorithm depends critically upon the entanglement present in
that state; the more entanglement, the less well the algorithm performs. More
precisely, suppose we take a pure state input, and prior to running the
algorithm apply local unitary operations to each qubit in order to maximize the
probability P_max that the search algorithm succeeds. We prove that, for pure
states, P_max is an entanglement monotone, in the sense that P_max can never be
decreased by local operations and classical communication.Comment: 7 page
Unitary Gate Synthesis for Continuous Variable Systems
We investigate the synthesis of continuous-variable two-mode unitary gates in
the setting where two modes A and B are coupled by a fixed quadratic
Hamiltonian H. The gate synthesis consists of a sequence of evolutions governed
by Hamiltonian H interspaced by local phase shifts applied to A and B. We
concentrate on protocols that require the minimum necessary number of steps and
we show how to implement the beam splitter and the two-mode squeezer in just
three steps. Particular attention is paid to the Hamiltonian x_A p_B that
describes the effective off-resonant interaction of light with the collective
atomic spin.Comment: 7 pages, minor text modifications, references adde
Supercatalysis
We show that entanglement-assisted transformations of bipartite entangled
states can be more efficient than catalysis [D. Jonathan and M. B. Plenio,
Phys. Rev. Lett. 83, 3566 (1999)}, i.e., given two incomparable bipartite
states not only can the transformation be enabled by performing collective
operations with an auxiliary entangled state, but the entanglement of the
auxiliary state itself can be enhanced. We refer to this phenomenon as
supercatalysis. We provide results on the properties of supercatalysis and its
relationship with catalysis. In particular, we obtain a useful necessary and
sufficient condition for catalysis, provide several sufficient conditions for
supercatalysis and study the extent to which entanglement of the auxiliary
state can be enhanced via supercatalysis.Comment: Latex, 5 page
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