3,025 research outputs found
Effects of carbon fibers on consumer products
The potential effects of carbon fibers on consumer products such as dishwashers, microwave ovens, and smoke detectors were investigated. The investigation was divided into two categories to determine the potential faults and hazards that could occur if fibers should enter the electrical circuits of the selected appliances. The categories were a fault analysis and a hazard analysis. Hazards considered were fire, flood, physical harm, explosion, and electrical shock. Electrical shock was found to be a possible occurrence related to carbon fibers. Faults were considered to be any effect on the performance of an appliance which would result in complaint or require service action
‘Yes-in-my-backyard’: Spatial differences in the valuation of forest services and local co-benefits for carbon markets in México
Forests provide many and large benefits, including cost-efficient climate change mitigation. However international
carbon markets have not stimulated the demand for forestry offsets. Domestic market-mechanisms are emerging inmany countries and forests could be highly valued through these policies asmost of the benefits produced
by forests are enjoyed locally. Here, a choice experiment explores drivers of valuation and willingness to
pay for forest carbon services in voluntary markets in Mexico by comparing the valuation of citizens from four
regions to test geographical preference for projects (n = 645). Findings from multinomial-logit models show
valuation of forest carbon services is transferable and citizens would pay more for offsets from projects closer
to their homes. Proximate forests provide a range of co-benefits to local users, including environmental services
and opportunities for recreation. Factors related to valuation include sense of responsibility, previous knowledge
of carbon emissions, previous visits to the sites, regional identification and the valuation of local environmental services (e.g. improvements in local air quality). Knowledge of spatial heterogeneity in valuation of the use of forest services can help to design market-based instruments by identifying highly valued areas for environmental services programs and carbon markets
Differential Evolution for Many-Particle Adaptive Quantum Metrology
We devise powerful algorithms based on differential evolution for adaptive
many-particle quantum metrology. Our new approach delivers adaptive quantum
metrology policies for feedback control that are orders-of-magnitude more
efficient and surpass the few-dozen-particle limitation arising in methods
based on particle-swarm optimization. We apply our method to the
binary-decision-tree model for quantum-enhanced phase estimation as well as to
a new problem: a decision tree for adaptive estimation of the unknown bias of a
quantum coin in a quantum walk and show how this latter case can be realized
experimentally.Comment: Fig. 2(a) is the cover of Physical Review Letters Vol. 110 Issue 2
High fidelity all-optical control of quantum dot spins: detailed study of the adiabatic approach
Confined electron spins are preferred candidates for embodying quantum
information in the solid state. A popular idea is the use of optical excitation
to achieve the ``best of both worlds'', i.e. marrying the long spin decoherence
times with rapid gating. Here we study an all-optical adiabatic approach to
generating single qubit phase gates. We find that such a gate can be extremely
robust against the combined effect of all principal sources of decoherence,
with an achievable fidelity of 0.999 even at finite temperature. Crucially this
performance can be obtained with only a small time cost: the adiabatic gate
duration is within about an order of magnitude of a simple dynamic
implementation. An experimental verification of these predictions is
immediately feasible with only modest resources
Quantum dynamics in a tiered non-Markovian environment
We introduce a new analytical method for studying the open quantum systems
problem of a discrete system weakly coupled to an environment of harmonic
oscillators. Our approach is based on a phase space representation of the
density matrix for a system coupled to a two-tiered environment. The dynamics
of the system and its immediate environment are resolved in a non-Markovian
way, and the environmental modes of the inner environment can themselves be
damped by a wider `universe'. Applying our approach to the canonical cases of
the Rabi and spin-boson models we obtain new analytical expressions for an
effective thermalisation temperature and corrections to the environmental
response functions as direct consequences of considering such a tiered
environment. A comparison with exact numerical simulations confirms that our
approximate expressions are remarkably accurate, while their analytic nature
offers the prospect of deeper understanding of the physics which they describe.
A unique advantage of our method is that it permits the simultaneous inclusion
of a continuous bath as well as discrete environmental modes, leading to wide
and versatile applicability.Comment: Video abstract available at
http://iopscience.iop.org/1367-2630/17/2/023063. 15 pages, 6 figure
Practicality of spin chain 'wiring' in diamond quantum technologies
Coupled spin chains are promising candidates for 'wiring up' qubits in
solid-state quantum computing (QC). In particular, two nitrogen-vacancy centers
in diamond can be connected by a chain of implanted nitrogen impurities; when
driven by a suitable global fields the chain can potentially enable quantum
state transfer at room temperature. However, our detailed analysis of error
effects suggests that foreseeable systems may fall far short of the fidelities
required for QC. Fortunately the chain can function in the more modest role as
a mediator of noisy entanglement, enabling QC provided that we use subsequent
purification. For instance, a chain of 5 spins with inter-spin distances of 10
nm has finite entangling power as long as the T2 time of the spins exceeds 0.55
ms. Moreover we show that re-purposing the chain this way can remove the
restriction to nearest-neighbor interactions, so eliminating the need for
complicated dynamical decoupling sequences.Comment: 5 pages (plus 5-page supplement
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