3,730 research outputs found
Pivoting makes the ZX-calculus complete for real stabilizers
We show that pivoting property of graph states cannot be derived from the
axioms of the ZX-calculus, and that pivoting does not imply local
complementation of graph states. Therefore the ZX-calculus augmented with
pivoting is strictly weaker than the calculus augmented with the Euler
decomposition of the Hadamard gate. We derive an angle-free version of the
ZX-calculus and show that it is complete for real stabilizer quantum mechanics.Comment: In Proceedings QPL 2013, arXiv:1412.791
Verifying the Steane code with Quantomatic
In this paper we give a partially mechanized proof of the correctness of
Steane's 7-qubit error correcting code, using the tool Quantomatic. To the best
of our knowledge, this represents the largest and most complicated verification
task yet carried out using Quantomatic.Comment: In Proceedings QPL 2013, arXiv:1412.791
Symmetry, Compact Closure and Dagger Compactness for Categories of Convex Operational Models
In the categorical approach to the foundations of quantum theory, one begins
with a symmetric monoidal category, the objects of which represent physical
systems, and the morphisms of which represent physical processes. Usually, this
category is taken to be at least compact closed, and more often, dagger
compact, enforcing a certain self-duality, whereby preparation processes
(roughly, states) are inter-convertible with processes of registration
(roughly, measurement outcomes). This is in contrast to the more concrete
"operational" approach, in which the states and measurement outcomes associated
with a physical system are represented in terms of what we here call a "convex
operational model": a certain dual pair of ordered linear spaces -- generally,
{\em not} isomorphic to one another. On the other hand, state spaces for which
there is such an isomorphism, which we term {\em weakly self-dual}, play an
important role in reconstructions of various quantum-information theoretic
protocols, including teleportation and ensemble steering. In this paper, we
characterize compact closure of symmetric monoidal categories of convex
operational models in two ways: as a statement about the existence of
teleportation protocols, and as the principle that every process allowed by
that theory can be realized as an instance of a remote evaluation protocol ---
hence, as a form of classical probabilistic conditioning. In a large class of
cases, which includes both the classical and quantum cases, the relevant
compact closed categories are degenerate, in the weak sense that every object
is its own dual. We characterize the dagger-compactness of such a category
(with respect to the natural adjoint) in terms of the existence, for each
system, of a {\em symmetric} bipartite state, the associated conditioning map
of which is an isomorphism
Understanding and responding when things go wrong: key principles for primary care educators
Learning from events with unwanted outcomes is an important part of
workplace based education and providing evidence for medical appraisal
and revalidation. It has been suggested that adopting a ‘systems approach’
could enhance learning and effective change. We believe the following key
principles should be understood by all healthcare staff, especially those
with a role in developing and delivering educational content for safety and
improvement in primary care.
When things go wrong, professional accountability involves accepting there
has been a problem, apologising if necessary and committing to learn and
change. This is easier in a ‘Just Culture’ where wilful disregard of safe
practice is not tolerated but where decisions commensurate with training
and experience do not result in blame and punishment. People usually
attempt to achieve successful outcomes, but when things go wrong the
contribution of hindsight and attribution bias as well as a lack of
understanding of conditions and available information (local rationality) can
lead to inappropriately blame ‘human error’. System complexity makes
reduction into component parts difficult; thus attempting to ‘find-and-fix’
malfunctioning components may not always be a valid approach. Finally,
performance variability by staff is often needed to meet demands or cope
with resource constraints.
We believe understanding these core principles is a necessary precursor to
adopting a ‘systems approach’ that can increase learning and reduce the
damaging effects on morale when ‘human error’ is blamed. This may
result in ‘human error’ becoming the starting point of an investigation and
not the endpoint
Strong Complementarity and Non-locality in Categorical Quantum Mechanics
Categorical quantum mechanics studies quantum theory in the framework of
dagger-compact closed categories.
Using this framework, we establish a tight relationship between two key
quantum theoretical notions: non-locality and complementarity. In particular,
we establish a direct connection between Mermin-type non-locality scenarios,
which we generalise to an arbitrary number of parties, using systems of
arbitrary dimension, and performing arbitrary measurements, and a new stronger
notion of complementarity which we introduce here.
Our derivation of the fact that strong complementarity is a necessary
condition for a Mermin scenario provides a crisp operational interpretation for
strong complementarity. We also provide a complete classification of strongly
complementary observables for quantum theory, something which has not yet been
achieved for ordinary complementarity.
Since our main results are expressed in the (diagrammatic) language of
dagger-compact categories, they can be applied outside of quantum theory, in
any setting which supports the purely algebraic notion of strongly
complementary observables. We have therefore introduced a method for discussing
non-locality in a wide variety of models in addition to quantum theory.
The diagrammatic calculus substantially simplifies (and sometimes even
trivialises) many of the derivations, and provides new insights. In particular,
the diagrammatic computation of correlations clearly shows how local
measurements interact to yield a global overall effect. In other words, we
depict non-locality.Comment: 15 pages (incl. 5 appendix). To appear: LiCS 201
Understanding patient safety performance and educational needs using the ‘Safety-II’ approach for complex systems
Participation in projects to improve patient safety is a key component of general practice (GP) specialty training, appraisal and revalidation. Patient safety training priorities for GPs at all career stages are described in the Royal College of General Practitioners’ curriculum. Current methods that are taught and employed to improve safety often use a ‘find-and-fix’ approach to identify components of a system (including humans) where performance could be improved. However, the complex interactions and inter-dependence between components in healthcare systems mean that cause and effect are not always linked in a predictable manner. The Safety-II approach has been proposed as a new way to understand how safety is achieved in complex systems that may improve quality and safety initiatives and enhance GP and trainee curriculum coverage. Safety-II aims to maximise the number of events with a successful outcome by exploring everyday work. Work-as-done often differs from work-as-imagined in protocols and guidelines and various ways to achieve success, dependent on work conditions, may be possible. Traditional approaches to improve the quality and safety of care often aim to constrain variability but understanding and managing variability may be a more beneficial approach. The application of a Safety-II approach to incident investigation, quality improvement projects, prospective analysis of risk in systems and performance indicators may offer improved insight into system performance leading to more effective change. The way forward may be to combine the Safety-II approach with ‘traditional’ methods to enhance patient safety training, outcomes and curriculum coverage
The adaptation of cognitive behavioural therapy for adult Maori clients with depression: A pilot study
A semistructured cognitive behavioural therapy (CBT) programme for depression was adapted for use with Maori adult clients with depression. Adaptations were developed in consultation with an advisory group consisting of Maori clinical psychologists and kaumatua with experience working in mental health services. The programme was piloted with 2 participants who were clients of a Maori mental health service. The programme builds on a more traditional CBT treatment programme by integrating concepts such as whakatauki, whanaungatanga, whanau involvement, and whakapapa into the therapeutic context. Despite limitations the results demonstrate considerable promise. Depressive symptoms increased substantially in both cases and both clients reflected positively on the adaptations incorporated into therapy
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