7,909 research outputs found
Some spectrometric results from the NASA 1968 Airborne Auroral Expedition and tentative identification of several N2 c prime /1 Sigma u plus/ yields a /1 Pi g/ bands in auroras
Spectrophotometric results from NASA 1968 Airborne Auroral Expedition and tentative identification of several molecular nitrogen emission band
Gold-free GaAs/GaAsSb heterostructure nanowires grown on silicon
Growth of GaAs/GaAsSb heterostructurenanowires on silicon without the need for gold seed particles is presented. A high vertical yield of GaAsnanowires is first obtained, and then GaAsâSbâËâ segments are successfully grown axially in these nanowires. GaAsSb can also be integrated as a shell around the GaAs core. Finally, two GaAsSb segments are grown inside a GaAsnanowire and passivated using an AlâGaâËâAs shell. It is found that no stacking faults or twin planes occur in the GaAsSb segments.Part of this work was funded by the Swedish Foundation for
Strategic Research SSF, the Swedish Research Council
VR, and the Knut and Alice Wallenberg Foundation
Curvature corrections in DGP brane cosmology
We consider a DGP inspired brane scenario where the action on the brane is
augmented by a function of the Ricci scalar, . The cosmological
implications that such a scenario entails are examined for and shown to
be consistent with a universe expanding with power-law acceleration. It is
shown that two classes of solutions exist for the usual FRW metric and small
Hubble radii. When the Hubble radius becomes larger, we either have a
transition to a fully 5D regime or to a self-inflationary solution which
produces a late accelerated expansion such that the radius becomes a function
of .Comment: 11 pages, 2 figure
Brans-Dicke DGP Brane Cosmology
We consider a five dimensional DGP-brane scenario endowed with a
non-minimally coupled scalar field within the context of Brans-Dicke theory.
This theory predicts that the mass appearing in the gravitational potential is
modified by the addition of the mass of the effective intrinsic curvature on
the brane. We also derive the effective four dimensional field equations on a
3+1 dimensional brane where the fifth dimension is assumed to have an orbifold
symmetry. Finally, we discuss the cosmological implications of this setup,
predicting an accelerated expanding universe with a value of the Brans-Dicke
parameter consistent with values resulting from the solar system
observations.Comment: 12 pages, 1 figure, to appear in JCA
Some photometer results obtained on the NASA 1969 Airborne Auroral Expedition
The spectral features measured by a photometer onboard the Convair 990 Galileo, during the Auroral Expedition are given in tables. The measurements given cover flights 3 to 15
Recommended from our members
A continuum of language comprehension: college students, agrammatics, and everone in between
Locking Local Oscillator Phase to the Atomic Phase via Weak Measurement
We propose a new method to reduce the frequency noise of a Local Oscillator
(LO) to the level of white phase noise by maintaining (not destroying by
projective measurement) the coherence of the ensemble pseudo-spin of atoms over
many measurement cycles. This scheme uses weak measurement to monitor the phase
in Ramsey method and repeat the cycle without initialization of phase and we
call, "atomic phase lock (APL)" in this paper. APL will achieve white phase
noise as long as the noise accumulated during dead time and the decoherence are
smaller than the measurement noise. A numerical simulation confirms that with
APL, Allan deviation is averaged down at a maximum rate that is proportional to
the inverse of total measurement time, tau^-1. In contrast, the current atomic
clocks that use projection measurement suppress the noise only down to the
level of white frequency, in which case Allan deviation scales as tau^-1/2.
Faraday rotation is one of the possible ways to realize weak measurement for
APL. We evaluate the strength of Faraday rotation with 171Yb+ ions trapped in a
linear rf-trap and discuss the performance of APL. The main source of the
decoherence is a spontaneous emission induced by the probe beam for Faraday
rotation measurement. One can repeat the Faraday rotation measurement until the
decoherence become comparable to the SNR of measurement. We estimate this
number of cycles to be ~100 cycles for a realistic experimental parameter.Comment: 18 pages, 7 figures, submitted to New Journal of Physic
Fragmentation pathways of nanofractal structures on surface
We present a detailed systematical theoretical analysis of the post-growth
processes occurring in nanofractals grown on surface. For this study we
developed a method which accounts for the internal dynamics of particles in a
fractal. We demonstrate that particle diffusion and detachment controls the
shape of the emerging stable islands on surface. We consider different
scenarios of fractal post-growth relaxation and analyze the time evolution of
the island's morphology. The results of our calculations are compared with
available experimental observations, and experiments in which the post-growth
relaxation of deposited nanostructures can be probed are suggested.Comment: 34 pages, 11 figure
General Formalism for Evaluating the Impact of Phase Noise on Bloch Vector Rotations
Quantum manipulation protocols for quantum sensors and quantum computation
often require many single qubit rotations. However, the impact of phase noise
in the field that performs the qubit rotations is often neglected or treated
only for special cases. We present a general framework for calculating the
impact of phase noise on the state of a qubit, as described by its equivalent
Bloch vector. The analysis applies to any Bloch vector orientation, and any
rotation axis azimuthal angle for both a single pulse, and pulse sequences.
Experimental examples are presented for several special cases. We apply the
analysis to commonly used composite -pulse sequences: CORPSE, SCROFULOUS,
and BB1, used to suppress static amplitude and detuning errors, and also to
spin echo sequences. We expect the formalism presented will help guide the
development and evaluation of future quantum manipulation protocols.Comment: 12 pages, 6 figures, submitted to PR
- âŚ