833 research outputs found
Non-linear optomechanical measurement of mechanical motion
Precision measurement of non-linear observables is an important goal in all
facets of quantum optics. This allows measurement-based non-classical state
preparation, which has been applied to great success in various physical
systems, and provides a route for quantum information processing with otherwise
linear interactions. In cavity optomechanics much progress has been made using
linear interactions and measurement, but observation of non-linear mechanical
degrees-of-freedom remains outstanding. Here we report the observation of
displacement-squared thermal motion of a micro-mechanical resonator by
exploiting the intrinsic non-linearity of the radiation pressure interaction.
Using this measurement we generate bimodal mechanical states of motion with
separations and feature sizes well below 100~pm. Future improvements to this
approach will allow the preparation of quantum superposition states, which can
be used to experimentally explore collapse models of the wavefunction and the
potential for mechanical-resonator-based quantum information and metrology
applications.Comment: 8 pages, 4 figures, extensive supplementary material available with
published versio
Evolution of the Fucaceae (Phaeophyceae) inferred from nrDNA-ITS
Sequences of the internal transcribed spacer region (ITS-1, 5.8S, and ITS-2) of nuclear ribosomal DNA were obtained from 16 species representing all six genera of Fucaceae (Ascophyllum, Fucus, Hesperophycus, Pelvetia, Pelvetiopsis, and Xiphophora) plus one outgroup (Hormosira). Parsimony analysis indicated that the family Fucaceae is monophyletic and that the northern hemisphere taxa are highly divergent from the only southern hemisphere genus, Xiphophora. The genus Pelvetia is not monophyletic because the European P. canaliculata is more closely related to Fucus, Hesperophycus, and Pelvetiopsis than to other Pelvetia species. We establish Silvetia, gen. nov. and transfer the 3 Pacific species of Pelvetia to the new genus. Fucus is monophyletic and not ancestral in the Fucaceae. The ITS sequences identified two strongly supported lineages within Fucus, one with F. serratus sister to the clade containing F. gardneri, F. distichus, and F. evanescens and a second including F. vesiculosus, F. spiralis, F. ceranoides, and F. virsoides. The ITS was not useful for resolving relationships within each of these clusters and between populations of F. vesiculosus. Within-individual variation in ITS sequences is high in Fucus, a derived genus, compared to Ascophyllum, a more ancestral genus. Mapping of the two characters that form the basis of Powell’s model for speciation in the Fucaceae showed that 1) number of eggs per oogonium has not followed a gradual reduction and that 2) monoecy/dioecy has changed several times during evolution of this family
Integrating the Core: A New Management Curriculum to Empower our Students
This paper follows Kennesaw State University\u27s (KSU) faculty journal in developing a new integrated core curriculum for their Management majors that will empower the students and meet the needs of today\u27s employers. Curriculums must change to stay current. Depending on the amount of change, this can be a huge undertaking for a department ensconced in an existing curriculum paradigm, and can be met with resistance. In this paper we look for answers to: 1) Why is the change necessary? 2) What are we changing to? We will follow up with some thoughts about 3) how will we make these changes
Absolute differential positronium-formation cross sections
The first absolute experimental determinations of the differential cross-sections for the formation of ground-state positronium are presented for He, Ar, H2 and CO2 near 0â—‹. Results are compared with available theories. The ratio of the differential and integrated cross-sections for the targets exposes the higher propensity for forward-emission of positronium formed from He and H2
History on trial: evaluating learning outcomes through audit and accreditation in a national standards environment
This paper uses a trial audit of history programs undertaken in 2011-2012 to explore issues surrounding the attainment of Threshold Learning Outcomes (TLOs) in an emerging Australian national standards environment for the discipline of history. The audit sought to ascertain whether an accreditation process managed by the discipline under the auspices of the Australian Historical Association (AHA) could be based on a limited-intervention, “light-touch” approach to assessing attainment of the TLOs. The results of the audit show that successful proof of TLO attainment would only be possible with more active intervention into existing history majors and courses. Assessments across all levels of history teaching would have to be designed, undertaken, and marked using a rubric matched to the TLOs. It proved unrealistic to expect students to demonstrate acquisition of the TLOs from existing teaching and assessment practices. The failure of the “light-touch” audit process indicates that demonstrating student attainment under a national standards regime would require fundamental redevelopment of the curriculum. With standards-based approaches to teaching and learning emerging as international phenomena, this case study resonates beyond Australia and the discipline under investigation.Sean Brawley, Jennifer Clark, Chris Dixon, Lisa Ford, Erik Nielsen, Shawn Ross, Stuart Upto
Mechanical squeezing via fast continuous measurement
We revisit quantum state preparation of an oscillator by continuous linear
position measurement. Quite general analytical expressions are derived for the
conditioned state of the oscillator. Remarkably, we predict that quantum
squeezing is possible outside of both the backaction dominated and quantum
coherent oscillation regimes, relaxing experimental requirements even compared
to ground-state cooling. This provides a new way to generate non-classical
states of macroscopic mechanical oscillators, and opens the door to quantum
sensing and tests of quantum macroscopicity at room temperature
Complete Break Up of Ortho Positronium (Ps)- Hydrogenic ion System
The dynamics of the complete breakup process in an Ortho Ps - He+ system
including electron loss to the continuum (ELC) is studied where both the
projectile and the target get ionized. The process is essentially a four body
problem and the present model takes account of the two centre effect on the
electron ejected from the Ps atom which is crucial for a proper description of
the ELC phenomena. The calculations are performed in the framework of Coulomb
Distorted Eikonal Approximation. The exchange effect between the target and the
projectile electron is taken into account in a consistent manner. The proper
asymptotic 3-body boundary condition for this ionization process is also
satisfied in the present model. A distinct broad ELC peak is noted in the fully
differential cross sections (5DCS) for the Ps electron corroborating
qualitatively the experiment for the Ps - He system. Both the dynamics of the
ELC from the Ps and the ejected electron from the target He+ in the FDCS are
studied using coplanar geometry. Interesting features are noted in the FDCS for
both the electrons belonging to the target and the projectile.Comment: 14 pages,7 figure
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