969,981 research outputs found
Magnifying superlens in the visible frequency range
In this communication we introduce a new design of the magnifying superlens
and demonstrate it in the experiment.Comment: 3pages, 1 figur
Far-field optical microscope with nanometer-scale resolution based on in-plane surface plasmon imaging
A new far-field optical microscopy technique capable of reaching
nanometer-scale resolution has been developed recently using the in-plane image
magnification by surface plasmon polaritons. This microscopy is based on the
optical properties of a metal-dielectric interface that may, in principle,
provide extremely large values of the effective refractive index n up to
100-1000 as seen by the surface plasmons. Thus, the theoretical diffraction
limit on resolution becomes lambda/2n, and falls into the nanometer-scale
range. The experimental realization of the microscope has demonstrated the
optical resolution better than 50 nm for 502 nm illumination wavelength.
However, the theory of such surface plasmon-based far-field microscope
presented so far gives an oversimplified picture of its operation. For example,
the imaginary part of the metal dielectric constant severely limits the
surface-plasmon propagation and the shortest attainable wavelength in most
cases, which in turn limits the microscope magnification. Here I describe how
this limitation has been overcome in the experiment, and analyze the practical
limits on the surface plasmon microscope resolution. In addition, I present
more experimental results, which strongly support the conclusion of extremely
high spatial resolution of the surface plasmon microscope.Comment: 23 pages, 9 figures, will be published in the topical issue on
Nanostructured Optical Metamaterials of the Journal of Optics A: Pure and
Applied Optics, Manuscript revised in response to referees comment
The Deflection of the Two Interacting Coronal Mass Ejections of 2010 May 23-24 as Revealed by Combined In situ Measurements and Heliospheric Imaging
In 2010 May 23-24, SDO observed the launch of two successive coronal mass
ejections (CMEs), which were subsequently tracked by the SECCHI suite onboard
STEREO. Using the COR2 coronagraphs and the heliospheric imagers (HIs), the
initial direction of both CMEs is determined to be slightly west of the
Sun-Earth line. We derive the CME kinematics, including the evolution of the
CME expansion until 0.4 AU. We find that, during the interaction, the second
CME decelerates from a speed above 500 km/s to 380 km/s the speed of the
leading edge of the first CME. STEREO observes a complex structure composed of
two different bright tracks in HI2-A but only one bright track in HI2-B. In
situ measurements from Wind show an "isolated" ICME, with the geometry of a
flux rope preceded by a shock. Measurements in the sheath are consistent with
draping around the transient. By combining remote-sensing and in situ
measurements, we determine that this event shows a clear instance of deflection
of two CMEs after their collision, and we estimate the deflection of the first
CME to be about 10 degrees towards the Sun-Earth line. The arrival time,
arrival speed and radius at Earth of the first CME are best predicted from
remote-sensing observations taken before the collision of the CMEs. Due to the
over-expansion of the CME after the collision, there are few, if any, signs of
interaction in in situ measurements. This study illustrates that complex
interactions during the Sun-to-Earth propagation may not be revealed by in situ
measurements alone.Comment: 14 pages, 8 figures, 1 table, accepted to the Astrophysical Journa
Bimodal conductance distribution of Kitaev edge modes in topological superconductors
A two-dimensional superconductor with spin-triplet p-wave pairing supports
chiral or helical Majorana edge modes with a quantized (length -independent)
thermal conductance. Sufficiently strong anisotropy removes both chirality and
helicity, doubling the conductance in the clean system and imposing a
super-Ohmic decay in the presence of disorder. We explain the
absence of localization in the framework of the Kitaev Hamiltonian, contrasting
the edge modes of the two-dimensional system with the one-dimensional Kitaev
chain. While the disordered Kitaev chain has a log-normal conductance
distribution peaked at an exponentially small value, the Kitaev edge has a
bimodal distribution with a second peak near the conductance quantum. Shot
noise provides an alternative, purely electrical method of detection of these
charge-neutral edge modes.Comment: 11 pages, 13 figure
Substructure in Tidal Streams; Tributaries in the Anticenter Ring
We report on the detection in Sloan Digital Sky Survey data of at least
three, roughly parallel components in a 65 degree-long stellar stream complex
previously identified with the Anticenter or Monoceros Ring. The three-stream
complex varies in width from 4 to 6 degrees along its length and appears to be
made up of two or more narrow substreams as well as a broader, diffuse
component. The width and complexity of the stream indicate that the progenitor
was likely a dwarf galaxy of significant size and mass. The stream is 8.9 kpc
distant and is oriented almost perpendicularly to our line of sight. The
visible portion of the stream does not pass near any known dwarf galaxies and a
preliminary orbit does not point to any viable progenitor candidates. Orbits
for the narrower substreams can be modeled with velocity offsets from the broad
component of about 8 km/s. We suggest that the broad component is likely to be
the remains of a dwarf galaxy, while the narrower streams constitute the
remnants of dynamically distinct components which may have included a native
population of globular clusters. While the color of the main sequence turn-off
is not unlike that for the Monoceros Ring, neither the visible stream nor any
reasonable projection of its orbit passes through Monoceros or Canis Major, and
we conclude that this stream is probably unrelated to the overdensities found
in these regions.Comment: 11 pages, 4 figures, accepted for publication in ApJ Letter
- …