2,534 research outputs found
Everett and the Born Rule
During the last ten years or so, derivations of the Born rule based on
decision theory have been proposed and developed, and it is claimed that these
are valid in the context of the Everett interpretation. This claim is
critically assessed and it is shown that one of its key assumptions, although
natural in the context of the Copenhagen interpretation, is not consistent with
that of Everett. It is further argued that any interpretation that relates
outcome likelihood to the expansion coefficients connecting the wavefunction
with the eigenfunctions of the measurement operator must be inconsistent with
the Everett interpretation.Comment: 22 pages 1 figur
ULF Waves above the Nightside Auroral Oval during Substorm Onset
This chapter reviews historical ground-based observations of ultra-low-frequency (ULF) waves tied to substorms, and highlights new research linking these ULF waves explicitly to substorm onset itself. There are several robust methods that can be used to determine the characteristics of a nonstationary time series such as the ULF magnetic field traces observed in the auroral zone during substorms. These include the pure state filter, the Hilbert-Huang transform, and wavelet analysis. The first indication of a substorm is a sudden brightening of one of the quiet arcs lying in the midnight sector of the oval. The chapter focuses on the properties of ULF waves that are seen in two-dimensional images of auroral intensity near substorm expansion phase onset. It also discusses a wider range of magnetotail instabilities that could be responsible for the azimuthally structured auroral forms at substorm onset
A New Coupling Potential for the Scattering of Deformed Light Heavy-Ions
This letter introduces a new coupling potential to explain the experimental
data over wide energy ranges for a number of systems. Within the
coupled-channels formalism, this letter first shows the limitations of the
standard coupled-channels theory in the case where one of the nuclei in the
reaction is strongly deformed and then, demonstrates that a global solution to
the problems of light heavy-ion reactions such as C+C,
O+Si and C+Mg can be found using a new
second-derivative coupling potential in the coupled-channels formalism. This
new approach consistently improves the agreement with the experimental data for
the elastic and inelastic scattering data as well as for their excitation
functions using constant or slightly energy-dependent parameters.Comment: 4 Pages, 5 Figures, submitted to the Phys. Lett.
All-optical non-demolition measurement of single-hole spin in a quantum-dot molecule
We propose an all-optical scheme to perform a non-demolition measurement of a
single hole spin localized in a quantum-dot molecule. The latter is embedded in
a microcavity and driven by two lasers. This allows to induce Raman transitions
which entangle the spin state with the polarization of the emitted photons. We
find that the measurement can be completed with high fidelity on a timescale of
100 ps, shorter than the typical T2. Furthermore, we show that the scheme can
be used to induce and observe spin oscillations without the need of
time-dependent magnetic fields
Exciton-assisted optomechanics with suspended carbon nanotubes
We propose a framework for inducing strong optomechanical effects in a
suspended carbon nanotube based on deformation potential exciton-phonon
coupling. The excitons are confined using an inhomogeneous axial electric field
which generates optically active quantum dots with a level spacing in the
milli-electronvolt range and a characteristic size in the 10-nanometer range. A
transverse field induces a tunable parametric coupling between the quantum dot
and the flexural modes of the nanotube mediated by electron-phonon
interactions. We derive the corresponding excitonic deformation potentials and
show that this interaction enables efficient optical ground-state cooling of
the fundamental mode and could allow us to realise the strong and ultra-strong
coupling regimes of the Jaynes-Cummings and Rabi models.Comment: 25 pages, 2 figure
Vaccines – but not as we know them: An ethical evaluation of HPV vaccination policy in Australia
Objective: To show how systematic ethical evaluation of public health policy may reveal issues of moral significance for critical examination. Method: Using Australia's human papillomavirus (HPV) vaccination program as an exemplar and adopting an approach outlined elsewhere, we determine whether conditions of effectiveness, proportionality, necessity and least infringement, and public justification, are met such that any breach of autonomy or justice principles associated with this intervention can be defended. Conclusions: While the HPV vaccine itself may be efficacious, some aspects of the program lack sufficient moral justification and raise concerns around procedural and social justice and gender equity. Implications: Public health interventions deploying new technologies against new targets – such as vaccines against cancer and chronic illness – require approaches crafted to their specific risk-benefit profiles that have carefully considered the ethical issues involved. Systematic ethical reflection is a useful tool for this
Nonlinear nanomechanical resonators for quantum optoelectromechanics
We present a scheme for tuning and controlling nano mechanical resonators by
subjecting them to electrostatic gradient fields, provided by nearby tip
electrodes. We show that this approach enables access to a novel regime of
optomechanics, where the intrinsic nonlinearity of the nanoresonator can be
explored. In this regime, one or several laser driven cavity modes coupled to
the nanoresonator and suitably adjusted gradient fields allow to control the
motional state of the nanoresonator at the single phonon level. Some
applications of this platform have been presented previously [New J. Phys. 14,
023042 (2012), Phys. Rev. Lett. 110, 120503 (2013)]. Here, we provide a
detailed description of the corresponding setup and its optomechanical coupling
mechanisms, together with an in-depth analysis of possible sources of damping
or decoherence and a discussion of the readout of the nanoresonator state.Comment: 15 pages, 6 figure
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