600 research outputs found
Non-Markovian entanglement dynamics in coupled superconducting qubit systems
We theoretically analyze the entanglement generation and dynamics by coupled
Josephson junction qubits. Considering a current-biased Josephson junction
(CBJJ), we generate maximally entangled states. In particular, the entanglement
dynamics is considered as a function of the decoherence parameters, such as the
temperature, the ratio between the reservoir cutoff
frequency and the system oscillator frequency , % between
the characteristic frequency of the %quantum system of interest, and
the cut-off frequency of %Ohmic reservoir and the energy levels
split of the superconducting circuits in the non-Markovian master equation. We
analyzed the entanglement sudden death (ESD) and entanglement sudden birth
(ESB) by the non-Markovian master equation. Furthermore, we find that the
larger the ratio and the thermal energy , the shorter the
decoherence. In this superconducting qubit system we find that the entanglement
can be controlled and the ESD time can be prolonged by adjusting the
temperature and the superconducting phases which split the energy
levels.Comment: 13 pages, 3 figure
Elementary operations for quantum logic with a single trapped two-level cold ion beyond Lamb-Dicke limit
A simple alternative scheme for implementing quantum gates with a single
trapped cold two-level ion beyond the Lamb-Dicke (LD) limit is proposed. Basing
on the quantum dynamics for the laser-ion interaction described by a
generalized Jaynes-Cummings model, one can introduce two kinds of elementary
quantum operations i.e., the simple rotation on the bare atomic state,
generated by applying a resonant pulse, and the joint operation on the internal
and external degrees of the ion, performed by using an off-resonant pulse.
Several typical quantum gates, including Hadamard gate, controlled-Z and
controlled-NOT gates , can thus be implemented exactly by using these
elementary operations. The experimental parameters including the LD parameter
and the durations of the applied laser pulses, for these implementation are
derived analytically and numerically. Neither the LD approximation for the
laser-ion interaction nor the auxiliary atomic level is needed in the present
scheme.Comment: 5 pages, no figure, to appear in Opt. Com
Rigidity of minimal submanifolds in hyperbolic space
We prove that if an -dimensional complete minimal submanifold in
hyperbolic space has sufficiently small total scalar curvature then has
only one end. We also prove that for such there exist no nontrivial
harmonic 1-forms on
Effects of decoherence and errors on Bell-inequality violation
We study optimal conditions for violation of the Clauser-Horne-Shimony-Holt
form of the Bell inequality in the presence of decoherence and measurement
errors. We obtain all detector configurations providing the maximal Bell
inequality violation for a general (pure or mixed) state. We consider local
decoherence which includes energy relaxation at the zero temperature and
arbitrary dephasing. Conditions for the maximal Bell-inequality violation in
the presence of decoherence are analyzed both analytically and numerically for
the general case and for a number of important special cases. Combined effects
of measurement errors and decoherence are also discussed.Comment: 18 pages, 5 figure
Interacting New Agegraphic Dark Energy in a Cyclic Universe
The main goal of this work is investigation of NADE in the cyclic universe
scenario. Since, cyclic universe is explained by a phantom phase (),
it is shown when there is no interaction between matter and dark energy, ADE
and NADE do not produce a phantom phase, then can not describe cyclic universe.
Therefore, we study interacting models of ADE and NADE in the modified
Friedmann equation. We find out that, in the high energy regime, which it is a
necessary part of cyclic universe evolution, only NADE can describe this
phantom phase era for cyclic universe. Considering deceleration parameter tells
us that the universe has a deceleration phase after an acceleration phase, and
NADE is able to produce a cyclic universe. Also it is found valuable to study
generalized second law of thermodynamics. Since the loop quantum correction is
taken account in high energy regime, it may not be suitable to use standard
treatment of thermodynamics, so we turn our attention to the result of
\citep{29}, which the authors have studied thermodynamics in loop quantum
gravity, and we show that which condition can satisfy generalized second law of
thermodynamics.Comment: 8 pages, 3 figure
HOPX functions as a tumour suppressor in head and neck cancer.
Head and neck squamous cell carcinoma (HNSCC) is generalized term that encompasses a diverse group of cancers that includes tumours of the oral cavity (OSCC), oropharynx (OPSCC) and nasopharynx (NPC). Genetic alterations that are common to all HNSCC types are likely to be important for squamous carcinogenesis. In this study, we have investigated the role of the homeodomain-only homeobox gene, HOPX, in the pathogenesis of HNSCC. We show that HOPX mRNA levels are reduced in OSCC and NPC cell lines and tissues and there is a general reduction of HOPX protein expression in these tumours and OPSCCs. HOPX promoter methylation was observed in a subset of HNSCCs and was associated with a worse overall survival in HPV negative tumours. RNAseq analysis of OSCC cells transfected with HOPX revealed a widespread deregulation of the transcription of genes related to epithelial homeostasis and ectopic over-expression of HOPX in OSCC and NPC cells inhibited cell proliferation, plating efficiency and migration, and enhanced sensitivity to UVA-induced apoptosis. Our results demonstrate that HOPX functions as a tumour suppressor in HNSCC and suggest a central role for HOPX in suppressing epithelial carcinogenesis
Structural, Electronic, and Magnetic Properties of MnO
We calculate the structural, electronic, and magnetic properties of MnO from
first principles, using the full-potential linearized augmented planewave
method, with both local-density and generalized-gradient approximations to
exchange and correlation. We find the ground state to be of rhombohedrally
distorted B1 structure with compression along the [111] direction,
antiferromagnetic with type-II ordering, and insulating, consistent with
experiment. We show that the distortion can be understood in terms of a
Heisenberg model with distance dependent nearest-neighbor and
next-nearest-neighbor couplings determined from first principles. Finally, we
show that magnetic ordering can induce significant charge anisotropy, and give
predictions for electric field gradients in the ground-state rhombohedrally
distorted structure.Comment: Submitted to Physical Review B. Replaced: regenerated figures to
resolve font problems in automatically generated pd
Characterization of rate-dependent shear behavior of Zr-based bulk metallic glass using shear-punch testing
QED Effective Action at Finite Temperature: Two-Loop Dominance
We calculate the two-loop effective action of QED for arbitrary constant
electromagnetic fields at finite temperature T in the limit of T much smaller
than the electron mass. It is shown that in this regime the two-loop
contribution always exceeds the influence of the one-loop part due to the
thermal excitation of the internal photon. As an application, we study light
propagation and photon splitting in the presence of a magnetic background field
at low temperature. We furthermore discover a thermally induced contribution to
pair production in electric fields.Comment: 34 pages, 4 figures, LaTe
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