7,335 research outputs found
Final-state read-out of exciton qubits by observing resonantly excited photoluminescence in quantum dots
We report on a new approach to detect excitonic qubits in semiconductor
quantum dots by observing spontaneous emissions from the relevant qubit level.
The ground state of excitons is resonantly excited by picosecond optical
pulses. Emissions from the same state are temporally resolved with picosecond
time resolution. To capture weak emissions, we greatly suppress the elastic
scattering of excitation beams, by applying obliquely incident geometry to the
micro photoluminescence set-up. Rabi oscillations of the ground-state excitons
appear to be involved in the dependence of emission intensity on excitation
amplitude.Comment: 4 pages, 4 figures, to appear in Appl. Phys. Let
Surface Shubnikov-de Hass oscillations and non-zero Berry phases of the topological hole conduction in TlBiSe
We report the observation of two-dimensional Shubnikov-de Hass (SdH)
oscillations in the topological insulator TlBiSe. Hall
effect measurements exhibited electron-hole inversion in samples with bulk
insulating properties. The SdH oscillations accompanying the hole conduction
yielded a large surface carrier density of /cm, with the Landau-level fan diagram exhibiting the
Berry phase. These results showed the electron-hole reversibility around the
in-gap Dirac point and the hole conduction on the surface Dirac cone without
involving the bulk metallic conduction.Comment: 5 pages, 4 figure
Parametric instabilities in the LCGT arm cavity
We evaluated the parametric instabilities of LCGT (Japanese interferometric
gravitational wave detector project) arm cavity. The number of unstable modes
of LCGT is 10-times smaller than that of Advanced LIGO (U.S.A.). Since the
strength of the instabilities of LCGT depends on the mirror curvature more
weakly than that of Advanced LIGO, the requirement of the mirror curvature
accuracy is easier to be achieved. The difference in the parametric
instabilities between LCGT and Advanced LIGO is because of the thermal noise
reduction methods (LCGT, cooling sapphire mirrors; Advanced LIGO, fused silica
mirrors with larger laser beams), which are the main strategies of the
projects. Elastic Q reduction by the barrel surface (0.2 mm thickness
TaO) coating is effective to suppress instabilities in the LCGT arm
cavity. Therefore, the cryogenic interferometer is a smart solution for the
parametric instabilities in addition to thermal noise and thermal lensing.Comment: 6 pages,3 figures. Amaldi7 proceedings, J. Phys.: Conf. Ser.
(accepted
Spin melting and refreezing driven by uniaxial compression on a dipolar hexagonal plate
We investigate freezing characteristics of a finite dipolar hexagonal plate
by the Monte Carlo simulation. The hexagonal plate is cut out from a piled
triangular lattice of three layers with FCC-like (ABCABC) stacking structure.
In the present study an annealing simulation is performed for the dipolar plate
uniaxially compressed in the direction of layer-piling. We find spin melting
and refreezing driven by the uniaxial compression. Each of the melting and
refreezing corresponds one-to-one with a change of the ground states induced by
compression. The freezing temperatures of the ground-state orders differ
significantly from each other, which gives rise to the spin melting and
refreezing of the present interest. We argue that these phenomena are
originated by a finite size effect combined with peculiar anisotropic nature of
the dipole-dipole interaction.Comment: Proceedings of the Highly Frustrated Magnetism (HFM2006) conference.
To appear in a special issue of J. Phys. Condens. Matte
Gravitational waveforms for spinning compact binaries
The rotation of the bodies and the eccentricity of the orbit have significant
effects on the emitted gravitational radiation of binary systems. This work
focuses on the evaluation of the gravitational wave polarization states for
spinning compact binaries. We consider binaries on eccentric orbits and the
spin-orbit interaction up to the 1.5 post-Newtonian order in a way which is
independent of the parameterization of the orbit. The equations of motion for
angular variables are included. The formal expressions of the polarization
states are given with the inclusion of higher order corrections to the
waveform
Precise determination of two-carrier transport properties in the topological insulator TlBiSe
We report the electric transport study of the three-dimensional topological
insulator TlBiSe. We applied a newly developed analysis procedure and
precisely determined two-carrier transport properties. Magnetotransport
properties revealed a multicarrier conduction of high- and low-mobility
electrons in the bulk, which was in qualitative agreement with angle-resolved
photoemission results~[K. Kuroda , Phys. Rev. Lett. , 146801
(2010)]. The temperature dependence of the Hall mobility was explained well
with the conventional Bloch-Gr{\"u}neisen formula and yielded the Debye
temperature ~K. The results indicate that the
scattering of bulk electrons is dominated by acoustic phonons.Comment: 6 pages, 5 figures, to be published in Physical Review
Nucleosynthesis in 2D Core-Collapse Supernovae of 11.2 and 17.0 M Progenitors: Implications for Mo and Ru Production
Core-collapse supernovae are the first polluters of heavy elements in the
galactic history. As such, it is important to study the nuclear compositions of
their ejecta, and understand their dependence on the progenitor structure
(e.g., mass, compactness, metallicity). Here, we present a detailed
nucleosynthesis study based on two long-term, two-dimensional core-collapse
supernova simulations of a 11.2 M and a 17.0 M star. We
find that in both models nuclei well beyond the iron group (up to ) can be produced, and discuss in detail also the nucleosynthesis of the
p-nuclei Mo and Ru. While we observe the production of
Mo and Mo in slightly neutron-rich conditions in both
simulations, Ru can only be produced efficiently via the
p-process. Furthermore, the production of Ru in the p-process heavily
depends on the presence of very proton-rich material in the ejecta. This
disentanglement of production mechanisms has interesting consequences when
comparing to the abundance ratios between these isotopes in the solar system
and in presolar grains.Comment: 48 pages, 19 figures, accepted for publication in: J. Phys. G: Nucl.
Part. Phy
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