601 research outputs found
Full control of quadruple quantum dot circuit charge states in the single electron regime
We report the realization of an array of four tunnel coupled quantum dots in
the single electron regime, which is the first required step toward a scalable
solid state spin qubit architecture. We achieve an efficient tunability of the
system but also find out that the conditions to realize spin blockade readout
are not as straightforwardly obtained as for double and triple quantum dot
circuits. We use a simple capacitive model of the series quadruple quantum dots
circuit to investigate its complex charge state diagrams and are able to find
the most suitable configurations for future Pauli spin blockade measurements.
We then experimentally realize the corresponding charge states with a good
agreement to our model.Comment: 4 pages, 3 figure
Nonlinear deformed su(2) algebras involving two deforming functions
The most common nonlinear deformations of the su(2) Lie algebra, introduced
by Polychronakos and Ro\v cek, involve a single arbitrary function of J_0 and
include the quantum algebra su_q(2) as a special case. In the present
contribution, less common nonlinear deformations of su(2), introduced by
Delbecq and Quesne and involving two deforming functions of J_0, are reviewed.
Such algebras include Witten's quadratic deformation of su(2) as a special
case. Contrary to the former deformations, for which the spectrum of J_0 is
linear as for su(2), the latter give rise to exponential spectra, a property
that has aroused much interest in connection with some physical problems.
Another interesting algebra of this type, denoted by , has two
series of (N+1)-dimensional unitary irreducible representations, where N=0, 1,
2, .... To allow the coupling of any two such representations, a generalization
of the standard Hopf axioms is proposed. The resulting algebraic structure,
referred to as a two-colour quasitriangular Hopf algebra, is described.Comment: 8 pages, LaTeX, no figures, submitted to Proc. 5th Int. Coll.
``Quantum Groups and Integrable Systems'', Prague, 20-22 June 1996 (to be
published in Czech. J. Phys.
Mapping the contribution of Allied Health Professions to the wider public health workforce : a rapid review of evidence-based interventions
Objectives: The objective was to identify a selection of the best examples of the public health contributions by Allied Health Professionals (AHPs) in order to encourage a wider awareness and participation from that workforce to public health practice.
Study design: A mapping exercise was used to identify evidence-based interventions that could lead to health improvements across a population.
Methods: A rapid review was undertaken to identify evidence, followed by a survey of Allied Health Profession (AHP) practitioners and an expert panel consensus method to select the examples of AHP public health interventions.
Results: Nine evidence-based interventions are identified and selected as examples of current AHP good practice. These examples represent a contribution to public health and include screening interventions, secondary prevention and risk management.
Conclusions: This study contributes to a strategy for AHPs in public health by appraising the effectiveness and impact of some exemplar AHP practices that contribute to health improvement. There is a need for AHPs to measure the impact of their interventions and to demonstrate evidence of outcomes at population level.
Keywords: allied health professions; Applied Health Professionals; evidence-based practice; health improvement; public health; rapid revie
A fast quantum interface between different spin qubit encodings
Single-spin qubits in semiconductor quantum dots proposed by Loss and
DiVincenzo (LD qubits) hold promise for universal quantum computation with
demonstrations of a high single-qubit gate fidelity above 99.9 % and two-qubit
gates in conjunction with a long coherence time. However, initialization and
readout of a qubit is orders of magnitude slower than control, which is
detrimental for implementing measurement-based protocols such as
error-correcting codes. In contrast, a singlet-triplet (ST) qubit, encoded in a
two-spin subspace, has the virtue of fast readout with high fidelity and
tunable coupling to the electric field. Here, we present a hybrid system which
benefits from the different advantages of these two distinct spin-qubit
implementations. A quantum interface between the two codes is realized by
electrically tunable inter-qubit exchange coupling. We demonstrate a
controlled-phase (CPHASE) gate that acts within 5.5 ns, much faster than the
measured dephasing time of 211 ns. The presented hybrid architecture will be
useful to settle remaining key problems with building scalable spin-based
quantum computers
Expression, Purification, and Analysis of Unknown Translation Factors from Escherichia coli: A Synthesis Approach
New approaches are currently being developed to expose biochemistry and molecular biology undergraduates to a more interactive learning environment. Here, we propose a unique project-based laboratory module, which incorporates exposure to biophysical chemistry approaches to address problems in protein chemistry. Each of the experiments described herein contributes to the stepwise process of isolating, identifying, and analyzing a protein involved in a central biological process, prokaryotic translation. Students are provided with expression plasmids that harbor an unknown translation factor, and it is their charge to complete a series of experiments that will allow them to develop hypotheses for discovering the identity of their unknown (from a list of potential candidates). Subsequent to the identification of their unknown translation factor, a series of protein unfolding exercises are performed employing circular dichroism and fluorescence spectroscopies, allowing students to directly calculate thermodynamic parameters centered around determining the equilibrium constant for unfolding as a function of denaturant (temperature or chemical). The conclusion of this multi-part laboratory exercise consists of both oral and written presentations, emphasizing synthesis of the roles of each translation factor during the stepwise process of translation
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