425 research outputs found
Gold, copper, silver and aluminum nanoantennas to enhance spontaneous emission
We compute the decay rates of emitters coupled to spheroidal nanoantennas
made of gold, copper, silver, and aluminum. The spectral position of the
localized surface plasmon-polariton resonance, the enhancement factors and the
quantum efficiency are investigated as a function of the aspect ratio,
background index and the metal composing the nanoantenna. While copper yields
results similar to gold, silver and aluminum exhibit different performances.
Our results show that with a careful choice of the parameters these
nanoantennas can enhance emitters ranging from the UV to the near-IR spectrum.Comment: 7 pages, 10 figure
Coherent interaction of a metallic structure with a single quantum emitter: from super absorption to cloaking
We provide a general theoretical platform based on quantized radiation in
absorptive and inhomogeneous media for investigating the coherent interaction
of light with metallic structures in the immediate vicinity of quantum
emitters. In the case of a very small metallic cluster, we demonstrate extreme
regimes where a single emitter can either counteract or enhance particle
absorption by three orders of magnitude. For larger structures, we show that an
emitter can eliminate both scattering and absorption and cloak a plasmonic
antenna. We provide physical interpretations of our results and discuss their
applications in active metamaterials and quantum plasmonics
A high-fidelity photon gun: intensity-squeezed light from a single molecule
A two-level atom cannot emit more than one photon at a time. As early as the
1980s, this quantum feature was identified as a gateway to "single-photon
sources", where a regular excitation sequence would create a stream of light
particles with photon number fluctuations below the shot noise. Such an
intensity squeezed beam of light would be desirable for a range of applications
such as quantum imaging, sensing, enhanced precision measurements and
information processing. However, experimental realizations of these sources
have been hindered by large losses caused by low photon collection efficiencies
and photophysical shortcomings. By using a planar metallo-dielectric antenna
applied to an organic molecule, we demonstrate the most regular stream of
single photons reported to date. Measured intensity fluctuations reveal 2.2 dB
squeezing limited by our detection efficiency, equivalent to 6.2 dB intensity
squeezing right after the antenna.Comment: 9 pages, 3 figure
Extinction imaging of a single quantum emitter in its bright and dark states
Room temperature detection of single quantum emitters has had a broad impact
in fields ranging from biophysics to material science, photophysics, or even
quantum optics. These experiments have exclusively relied on the efficient
detection of fluorescence. An attractive alternative would be to employ direct
absorption, or more correctly expressed "extinction" measurements. Indeed,
small nanoparticles have been successfully detected using this scheme in
reflection and transmission. Coherent extinction detection of single emitters
has also been reported at cryogenic temperatures, but their room temperature
implementation has remained a great laboratory challenge owing to the expected
weak signal-to-noise ratio. Here we report the first extinction study of a
single quantum emitter at ambient condition. We obtain a direct measure for the
extinction cross section of a single semiconductor nanocrystal both during and
in the absence of fluorescence, for example in the photobleached state or
during blinking off-times. Our measurements pave the way for the detection and
absorption spectroscopy of single molecules or clusters of atoms even in the
quenched state
Highly efficient interfacing of guided plasmons and photons in nanowires
Successful exploitations of strongly confined surface plasmon-polaritons
critically rely on their efficient and rapid conversion to lossless channels.
We demonstrate a simple, robust, and broad-band butt-coupling technique for
connecting a metallic nanowire and a dielectric nanofiber. Conversion
efficiencies above 95% in the visible and close to 100% in the near infrared
can be achieved with realistic parameters. Moreover, by combining butt-coupling
with nanofocusing, we propose a broad-band high-throughput near-field optical
microscope.Comment: 5 figure
Polaritonic states in a dielectric nanoguide: localization and strong coupling
Propagation of light through dielectrics lies at the heart of optics.
However, this ubiquitous process is commonly described using phenomenological
dielectric function and magnetic permeability , i.e. without
addressing the quantum graininess of the dielectric matter. Here, we present a
theoretical study where we consider a one-dimensional ensemble of atoms in a
subwavelength waveguide (nanoguide) as fundamental building blocks of a model
dielectric. By exploring the roles of the atom-waveguide coupling efficiency,
density, disorder, and dephasing, we establish connections among various
features of polaritonic light-matter states such as localization, super and
subradiance, and strong coupling. In particular, we show that coherent multiple
scattering of light among atoms that are coupled via a single propagating mode
can gives rise to Rabi splitting. These results provide important insight into
the underlying physics of strong coupling reported by recent room-temperature
experiments with microcavities and surface plasmons.Comment: 10 pages, 6 figure
A Single-Emitter Gain Medium for Bright Coherent Radiation from a Plasmonic Nanoresonator
We theoretically demonstrate the generation and radiation of coherent
nanoplasmons powered by a single three-level quantum emitter on a plasmonic
nanoresonator. By pumping the three-level emitter in a Raman configuration, we
show a pathway to achieve macroscopic accumulation of nanoplasmons due to
stimulated emission in the nanoresonator despite their fast relaxation. Thanks
to the antenna effect of the nanoresonator, the system acts as an efficient and
bright nanoscopic coherent light source with a photon emission rate of hundreds
of Terahertz and could be realized with solid-state emitters at room
temperatures in pulse mode. We provide physical interpretations of the results
and discuss their realization and implications for ultra-compact integration of
optoelectronics.Comment: 15 pages, 7 figure
High-resolution spectroscopy of single Pr ions on the H-D transition
Rare earth ions in crystals exhibit narrow spectral features and
hyperfine-split ground states with exceptionally long coherence times. These
features make them ideal platforms for quantum information processing in the
solid state. Recently, we reported on the first high-resolution spectroscopy of
single Pr ions in yttrium orthosilicate (YSO) nanocrystals. While in
that work we examined the less explored H-P transition at a
wavelength of 488 nm, here we extend our investigations to the
H-D transition at 606 nm. In addition, we present measurements
of the second-order autocorrelation function, fluorescence lifetime, and
emission spectra of single ions as well as their polarization dependencies on
both transitions; these data were not within the reach of the first experiments
reported earlier. Furthermore, we show that by a proper choice of the
crystallite, one can obtain narrower spectral lines and, thus, resolve the
hyperfine levels of the excited state. We expect our results to make single-ion
spectroscopy accessible to a larger scientific community.Comment: 5 pages, 5 figure
Spontaneous emission in the near-field of 2D photonic crystals
We show theoretically that photonic crystal membranes cause large variations
in the spontaneous emission rate of dipole emitters, not only inside but also
in the near-field above the membranes. Our three-dimensional finite difference
time-domain calculations reveal an inhibition of more than five times and an
enhancement of more than ten times for the spontaneous emission rate of
emitters with select dipole orientations and frequencies. Furthermore we
demonstrate theoretically, the potential of a nanoscopic emitter attached to
the end of a glass fiber tip as a local probe for mapping the large spatial
variations of the photonic crystal local radiative density of states. This
arrangement is promising for on-command modification of the coupling between an
emitter and the photonic crystal in quantum optical experiments.Comment: 3 pages, 3 figures. Figure 2 colo
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