6,277 research outputs found
Electrical excitation of surface plasmons
We exploit a plasmon mediated two-step momentum downconversion scheme to
convert low-energy tunneling electrons into propagating photons. Surface
plasmon polaritons (SPPs) propagating along an extended gold nanowire are
excited on one end by low-energy electron tunneling and are then converted to
free-propagating photons at the other end. The separation of excitation and
outcoupling proofs that tunneling electrons excite gap plasmons that
subsequently couple to propagating plasmons. Our work shows that electron
tunneling provides a non-optical, voltage-controlled and low-energy pathway for
launching SPPs in nanostructures, such as plasmonic waveguide
Mechanism of Near-Field Raman Enhancement in One-Dimensional Systems
We develop a theory of near-field Raman enhancement in one-dimensional systems, and report supporting experimental results for carbon nanotubes. The enhancement is established by a laser-irradiated nanoplasmonic structure acting as an optical antenna. The near-field Raman intensity is inversely proportional to the 10th power of the separation between the enhancing structure and the one-dimensional system. Experimental data obtained from single-wall carbon nanotubes indicate that the Raman enhancement process is not significantly influenced by the specific phonon eigenvector, and is mainly defined by the properties of the nanoplasmonic structure
Extreme Long-time Dynamic Monte Carlo Simulations
We study the extreme long-time behavior of the metastable phase of the
three-dimensional Ising model with Glauber dynamics in an applied magnetic
field and at a temperature below the critical temperature. For these
simulations we use the advanced simulation method of projective dynamics. The
algorithm is described in detail, together with its application to the escape
from the metastable state. Our results for the field dependence of the
metastable lifetime are in good agreement with theoretical expectations and
span more than fifty decades in time.Comment: 13 pages with embedded eps figures. Int. J. Mod. Phys. C, in pres
Sub-Kelvin Parametric Feedback Cooling of a Laser-Trapped Nanoparticle
Recent experiments have demonstrated the ability to optically cool a
macroscopic mechanical oscillator to its quantum ground state by means of
dynamic backaction. Such experiments allow quantum mechanics to be tested with
mesoscopic objects, and represent an essential step toward quantum optical
memories, transducers, and amplifiers. Most oscillators considered so far are
rigidly connected to their thermal environment, fundamentally limiting their
mechanical Q-factors and requiring cryogenic precooling to liquid helium
temperatures. Here we demonstrate parametric feedback cooling of a
laser-trapped nanoparticle which is entirely isolated from the thermal bath.
The lack of a clamping mechanism provides robust decoupling from internal
vibrations and makes it possible to cool the nanoparticle in all degrees of
freedom by means of a single laser beam. Compared to laser-trapped
microspheres, nanoparticles have the advantage of higher resonance frequencies
and lower recoil heating, which are favorable conditions for quantum ground
state coolin
Comment on "Dynamic properties in a family of competitive growing models"
The article [Phys. Rev. E {\bf 73}, 031111 (2006)] by Horowitz and Albano
reports on simulations of competitive surface-growth models RD+X that combine
random deposition (RD) with another deposition X that occurs with probability
. The claim is made that at saturation the surface width obeys a
power-law scaling , where is only either
or , which is illustrated by the models where X is
ballistic deposition and where X is RD with surface relaxation. Another claim
is that in the limit , for any lattice size , the time evolution
of generally obeys the scaling , where is Family-Vicsek universal scaling function. We
show that these claims are incorrect.Comment: 2 pages, 3 figures, accepted for publication in Physical Review E in
Aug. 200
Mapping the local density of optical states of a photonic crystal with single quantum dots
We use single self-assembled InGaAs quantum dots as internal probes to map
the local density of optical states of photonic crystal membranes. The employed
technique separates contributions from non-radiative recombination and
spin-flip processes by properly accounting for the role of the exciton fine
structure. We observe inhibition factors as high as 55 and compare our results
to local density of optical states calculations available from the literature,
thereby establishing a quantitative understanding of photon emission in
photonic crystal membranes.Comment: 4 pages, 3 figure
Scanning emitter lifetime imaging microscopy for spontaneous emission control
We report an experimental technique to map and exploit the local density of
optical states of arbitrary planar nano-photonic structures. The method relies
on positioning a spontaneous emitter attached to a scanning probe
deterministically and reversibly with respect to its photonic environment while
measuring its lifetime. We demonstrate the method by imaging the enhancement of
the local density of optical states around metal nanowires. By
nano-positioning, the decay rate of a pointlike source of fluorescence can be
reversibly and repeatedly changed by a factor of two by coupling it to the
guided plasmonic mode of the wire
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