1,824 research outputs found
Extensions and further applications of the nonlocal Polyakov--Nambu--Jona-Lasinio model
The nonlocal Polyakov-loop-extended Nambu--Jona-Lasinio (PNJL) model is
further improved by including momentum-dependent wave-function renormalization
in the quark quasiparticle propagator. Both two- and three-flavor versions of
this improved PNJL model are discussed, the latter with inclusion of the
(nonlocal) 't Hooft-Kobayashi-Maskawa determinant interaction in order to
account for the axial U(1) anomaly. Thermodynamics and phases are investigated
and compared with recent lattice-QCD results.Comment: 28 pages, 11 figures, 4 tables; minor changes compared to v1;
extended conclusion
Qubit quantum-dot sensors: noise cancellation by coherent backaction, initial slips, and elliptical precession
We theoretically investigate the backaction of a sensor quantum dot with
strong local Coulomb repulsion on the transient dynamics of a qubit that is
probed capacitively. We show that the measurement backaction induced by the
noise of electron cotunneling through the sensor is surprisingly mitigated by
the recently identified coherent backaction [PRB 89, 195405] arising from
quantum fluctuations. This renormalization effect is missing in semiclassical
stochastic fluctuator models and typically also in Born-Markov approaches,
which try to avoid the calculation of the nonstationary, nonequilibrium state
of the qubit plus sensor. Technically, we integrate out the current-carrying
electrodes to obtain kinetic equations for the joint, nonequilibrium
detector-qubit dynamics. We show that the sensor-current response, level
renormalization, cotunneling, and leading non-Markovian corrections always
appear together and cannot be turned off individually in an experiment or
ignored theoretically. We analyze the backaction on the reduced qubit state -
capturing the full non-Markovian effects imposed by the sensor quantum dot on
the qubit - by applying a Liouville-space decomposition into quasistationary
and rapidly decaying modes. Importantly, the sensor cannot be eliminated
completely even in the simplest high-temperature, weak-measurement limit: The
qubit state experiences an initial slip that persists over many qubit cycles
and depends on the initial preparation of qubit plus sensor quantum dot. A
quantum-dot sensor can thus not be modeled as a 'black box' without accounting
for its dynamical variables. We furthermore find that the Bloch vector relaxes
(T1) along an axis that is not orthogonal to the plane in which the Bloch
vector dephases (T2), blurring the notions of T1 and T2 times. Finally, the
precessional motion of the Bloch vector is distorted into an ellipse in the
tilted dephasing plane.Comment: This is the version published in Phys. Rev.
Super-resolution provided by the arbitrarily strong superlinearity of the blackbody radiation
Blackbody radiation is a fundamental phenomenon in nature, and its explanation by Planck marks a cornerstone in the history of Physics. In this theoretical work, we show that the spectral radiance given by Planck's law is strongly superlinear with temperature, with an arbitrarily large local exponent for decreasing wavelengths. From that scaling analysis, we propose a new concept of super-resolved detection and imaging: if a focused beam of energy is scanned over an object that absorbs and linearly converts that energy into heat, a highly nonlinear thermal radiation response is generated, and its point spread function can be made arbitrarily smaller than the excitation beam focus. Based on a few practical scenarios, we propose to extend the notion of super-resolution beyond its current niche in microscopy to various kinds of excitation beams, a wide range of spatial scales, and a broader diversity of target objects
On the homomorphism order of labeled posets
Partially ordered sets labeled with k labels (k-posets) and their
homomorphisms are examined. We give a representation of directed graphs by
k-posets; this provides a new proof of the universality of the homomorphism
order of k-posets. This universal order is a distributive lattice. We
investigate some other properties, namely the infinite distributivity, the
computation of infinite suprema and infima, and the complexity of certain
decision problems involving the homomorphism order of k-posets. Sublattices are
also examined.Comment: 14 page
Measurement of focusing properties for high numerical aperture optics using an automated submicron beamprofiler
The focusing properties of three aspheric lenses with numerical aperture (NA)
between 0.53 and 0.68 were directly measured using an interferometrically
referenced scanning knife-edge beam profiler with sub-micron resolution. The
results obtained for two of the three lenses tested were in agreement with
paraxial gaussian beam theory. It was also found that the highest NA aspheric
lens which was designed for 830nm was not diffraction limited at 633nm. This
process was automated using motorized translation stages and provides a direct
method for testing the design specifications of high numerical aperture optics.Comment: 6 pages 4 figure
Ultrastructural anatomy of nodes of Ranvier in the peripheral nervous system as revealed by STED microscopy.
We used stimulated emission depletion (STED) superresolution microscopy to analyze the nanoscale organization of 12 glial and axonal proteins at the nodes of Ranvier of teased sciatic nerve fibers. Cytoskeletal proteins of the axon (betaIV spectrin, ankyrin G) exhibit a high degree of one-dimensional longitudinal order at nodal gaps. In contrast, axonal and glial nodal adhesion molecules [neurofascin-186, neuron glial-related cell adhesion molecule (NrCAM)] can arrange in a more complex, 2D hexagonal-like lattice but still feature a âŒ190-nm periodicity. Such a lattice-like organization is also found for glial actin. Sodium and potassium channels exhibit a one-dimensional periodicity, with the Nav channels appearing to have a lower degree of organization. At paranodes, both axonal proteins (betaII spectrin, Caspr) and glial proteins (neurofascin-155, ankyrin B) form periodic quasiâone-dimensional arrangements, with a high degree of interdependence between the position of the axonal and the glial proteins. The results indicate the presence of mechanisms that finely align the cytoskeleton of the axon with the one of the Schwann cells, both at paranodal junctions (with myelin loops) and at nodal gaps (with microvilli). Taken together, our observations reveal the importance of the lateral organization of proteins at the nodes of Ranvier and pave the way for deeper investigations of the molecular ultrastructural mechanisms involved in action potential propagation, the formation of the nodes, axonâglia interactions, and demyelination diseases
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