24,398 research outputs found
The dynamical Casimir effect in superconducting microwave circuits
We theoretically investigate the dynamical Casimir effect in electrical
circuits based on superconducting microfabricated waveguides with tunable
boundary conditions. We propose to implement a rapid modulation of the boundary
conditions by tuning the applied magnetic flux through superconducting quantum
interference devices (SQUIDs) that are embedded in the waveguide circuits. We
consider two circuits: (i) An open waveguide circuit that corresponds to a
single mirror in free space, and (ii) a resonator coupled to a microfabricated
waveguide, which corresponds to a single-sided cavity in free space. We analyze
the properties of the dynamical Casimir effect in these two setups by
calculating the generated photon-flux density, output-field correlation
functions, and the quadrature squeezing spectra. We show that these properties
of the output field exhibit signatures unique to the radiation due to the
dynamical Casimir effect, and could therefore be used for distinguishing the
dynamical Casimir effect from other types of radiation in these circuits. We
also discuss the similarities and differences between the dynamical Casimir
effect, in the resonator setup, and downconversion of pump photons in
parametric oscillators.Comment: 18 pages, 14 figure
Nonclassical microwave radiation from the dynamical Casimir effect
We investigate quantum correlations in microwave radiation produced by the
dynamical Casimir effect in a superconducting waveguide terminated and
modulated by a superconducting quantum interference device. We apply
nonclassicality tests and evaluate the entanglement for the predicted field
states. For realistic circuit parameters, including thermal background noise,
the results indicate that the produced radiation can be strictly nonclassical
and can have a measurable amount of intermode entanglement. If measured
experimentally, these nonclassicalilty indicators could give further evidence
of the quantum nature of the dynamical Casimir radiation in these circuits.Comment: 5 pages, 3 figure
Local consequences of applying international norms: differences in the application of forest certification in northern Sweden, northern Finland, and northwest Russia
Forest certification, developed in the early 1990s, is a process in which independent assessors grant use of the certification label to producers who meet certain environmental and social criteria set for their forest products. This label was quickly seen to offer a market advantage and to signal corporate social and environmental responsibility. This paper focuses on international norms pertaining to environmental and indigenous rights, as manifested in cases of Forest Stewardship Council (FSC)- and Programme for the Endorsement of Forest Certification (PEFC)-compatible certification, and how these norms have been applied domestically and perceived locally in different states. Case studies are drawn from northern Sweden, northern Finland, and three regions in northwest Russia. The studies illustrate that the choice and implementation of certification type depend considerably on national infrastructure and market characteristics and result in substantial differences in the impact that international norms have at the local leve
Scattering of coherent states on a single artificial atom
In this work we theoretically analyze a circuit QED design where propagating
quantum microwaves interact with a single artificial atom, a single Cooper pair
box. In particular, we derive a master equation in the so-called transmon
regime, including coherent drives. Inspired by recent experiments, we then
apply the master equation to describe the dynamics in both a two-level and a
three-level approximation of the atom. In the two-level case, we also discuss
how to measure photon antibunching in the reflected field and how it is
affected by finite temperature and finite detection bandwidth.Comment: 18 pages, 7 figure
Quasiperiodic localized oscillating solutions in the discrete nonlinear Schr\"odinger equation with alternating on-site potential
We present what we believe to be the first known example of an exact
quasiperiodic localized stable solution with spatially symmetric
large-amplitude oscillations in a non-integrable Hamiltonian lattice model. The
model is a one-dimensional discrete nonlinear Schr\"odinger equation with
alternating on-site energies, modelling e.g. an array of optical waveguides
with alternating widths. The solution bifurcates from a stationary discrete gap
soliton, and in a regime of large oscillations its intensity oscillates
periodically between having one peak at the central site, and two symmetric
peaks at the neighboring sites with a dip in the middle. Such solutions, termed
'pulsons', are found to exist in continuous families ranging arbitrarily close
both to the anticontinuous and continuous limits. Furthermore, it is shown that
they may be linearly stable also in a regime of large oscillations.Comment: 4 pages, 4 figures, to be published in Phys. Rev. E. Revised version:
change of title, added Figs. 1(b),(c), 4 new references + minor
clarification
Topical analgesia for acute otitis media
BACKGROUND: Acute otitis media (AOM) is a spontaneously remitting disease of which pain is the most distressing symptom. Antibiotics are now known to have less benefit than previously assumed. Topical pain relief may be a satisfactory intervention for AOM sufferers and encourage clinicians to prescribe fewer antibiotics. OBJECTIVES: To assess the effectiveness of topical analgesia for AOM in adults and children. SEARCH METHODS: For this second update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), Ovid MEDLINE (2008 to February Week 1 2011), Ovid MEDLINE (InâProcess & Other NonâIndexed Citations 10 February 2011), Ovid EMBASE (2008 to 2011 Week 05), EBSCO CINAHL (2008 to 4 February 2011) and Ovid AMED (2008 to April 2011). SELECTION CRITERIA: Doubleâblind randomised controlled trials (RCTs) or quasiâRCTs comparing an otic preparation with an analgesic effect (excluding antibiotics) versus placebo or an otic preparation with an analgesic effect (excluding antibiotics) versus any other otic preparation with an analgesic effect, in adults or children presenting at primary care settings with AOM without perforation. DATA COLLECTION AND ANALYSIS: Three review authors independently screened studies, assessed trial quality and extracted data. Attempts to obtain additional information from the trial authors of the included trials were unsuccessful. MAIN RESULTS: Five trials including 391 children aged three to 18 years met our criteria. Two studies (117 children) compared anaesthetic ear drops versus placebo immediately at diagnosis. All children received some form of oral pain relief. In all five studies it was clear that ear pain diminishes rapidly for most sufferers. Nevertheless there was a statistically significant difference in the proportion of children achieving a 50% reduction in pain in favour of anaesthetic drops 10 minutes after instillation (risk ratio (RR) 2.13, 95% confidence interval (CI) 1.19 to 3.80) and 30 minutes after instillation (RR 1.43, 95% CI 1.12 to 1.81) on the day AOM was diagnosed but not at 20 minutes (RR 1.24, 95% CI 0.88 to 1.74). Three trials (274 children) compared anaesthetic ear drops with naturopathic herbal ear drops. Naturopathic drops were favoured 15 and 30 minutes after instillation, one to three days after diagnosis, but the differences were not statistically significant. Only one trial looked at adverse reactions and found none. Overall the findings of this review are based on trial evidence that is at low or unclear risk of bias. AUTHORS' CONCLUSIONS: Evidence from five RCTs, only two of which addressed the most relevant question of primary effectiveness, provides limited evidence that ear drops are effective 30 minutes after administration in older children with AOM. Uncertainty exists as to the magnitude of this effect and more highâquality studies are needed
Edge scaling limits for a family of non-Hermitian random matrix ensembles
A family of random matrix ensembles interpolating between the GUE and the
Ginibre ensemble of matrices with iid centered complex Gaussian
entries is considered. The asymptotic spectral distribution in these models is
uniform in an ellipse in the complex plane, which collapses to an interval of
the real line as the degree of non-Hermiticity diminishes. Scaling limit
theorems are proven for the eigenvalue point process at the rightmost edge of
the spectrum, and it is shown that a non-trivial transition occurs between
Poisson and Airy point process statistics when the ratio of the axes of the
supporting ellipse is of order . In this regime, the family of
limiting probability distributions of the maximum of the real parts of the
eigenvalues interpolates between the Gumbel and Tracy-Widom distributions.Comment: 44 page
Internally Electrodynamic Particle Model: Its Experimental Basis and Its Predictions
The internally electrodynamic (IED) particle model was derived based on
overall experimental observations, with the IED process itself being built
directly on three experimental facts, a) electric charges present with all
material particles, b) an accelerated charge generates electromagnetic waves
according to Maxwell's equations and Planck energy equation and c) source
motion produces Doppler effect. A set of well-known basic particle equations
and properties become predictable based on first principles solutions for the
IED process; several key solutions achieved are outlined, including the de
Broglie phase wave, de Broglie relations, Schr\"odinger equation, mass,
Einstein mass-energy relation, Newton's law of gravity, single particle self
interference, and electromagnetic radiation and absorption; these equations and
properties have long been broadly experimentally validated or demonstrated. A
specific solution also predicts the Doebner-Goldin equation which emerges to
represent a form of long-sought quantum wave equation including gravity. A
critical review of the key experiments is given which suggests that the IED
process underlies the basic particle equations and properties not just
sufficiently but also necessarily.Comment: Presentation at the 27th Int Colloq on Group Theo Meth in Phys, 200
Prospects for cooling nanomechanical motion by coupling to a superconducting microwave resonator
Recent theoretical work has shown that radiation pressure effects can in
principle cool a mechanical degree of freedom to its ground state. In this
paper, we apply this theory to our realization of an opto-mechanical system in
which the motion of mechanical oscillator modulates the resonance frequency of
a superconducting microwave circuit. We present experimental data demonstrating
the large mechanical quality factors possible with metallic, nanomechanical
beams at 20 mK. Further measurements also show damping and cooling effects on
the mechanical oscillator due to the microwave radiation field. These data
motivate the prospects for employing this dynamical backaction technique to
cool a mechanical mode entirely to its quantum ground state.Comment: 6 pages, 6 figure
Optimal Topological Test for Degeneracies of Real Hamiltonians
We consider adiabatic transport of eigenstates of real Hamiltonians around
loops in parameter space. It is demonstrated that loops that map to nontrivial
loops in the space of eigenbases must encircle degeneracies. Examples from
Jahn-Teller theory are presented to illustrate the test. We show furthermore
that the proposed test is optimal.Comment: Minor corrections, accepted in Phys. Rev. Let
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