10 research outputs found
Terahertz-Mediated Microwave-to-Optical Transduction
Transduction of quantum signals between the microwave and the optical ranges
will unlock powerful hybrid quantum systems enabling information processing
with superconducting qubits and low-noise quantum networking through optical
photons. Most microwave-to-optical quantum transducers suffer from thermal
noise due to pump absorption. We analyze the coupled thermal and wave dynamics
in electro-optic transducers that use a two-step scheme based on an
intermediate frequency state in the THz range. Our analysis, supported by
numerical simulations, shows that the two-step scheme operating with a
continuous pump offers near-unity external efficiency with a multi-order noise
suppression compared to direct transduction. As a result, two-step
electro-optic transducers may enable quantum noise-limited interfacing of
superconducting quantum processors with optical channels at MHz-scale bitrates
FiND: Few-shot three-dimensional image-free confocal focusing on point-like emitters
Confocal fluorescence microscopy is widely applied for the study of
point-like emitters such as biomolecules, material defects, and quantum light
sources. Confocal techniques offer increased optical resolution, dramatic
fluorescence background rejection and sub-nanometer localization, useful in
super-resolution imaging of fluorescent biomarkers, single-molecule tracking,
or the characterization of quantum emitters. However, rapid, noise-robust
automated 3D focusing on point-like emitters has been missing for confocal
microscopes. Here, we introduce FiND (Focusing in Noisy Domain), an
imaging-free, non-trained 3D focusing framework that requires no hardware
add-ons or modifications. FiND achieves focusing for signal-to-noise ratios
down to 1, with a few-shot operation for signal-to-noise ratios above 5. FiND
enables unsupervised, large-scale focusing on a heterogeneous set of quantum
emitters. Additionally, we demonstrate the potential of FiND for real-time 3D
tracking by following the drift trajectory of a single NV center indefinitely
with a positional precision of < 10 nm. Our results show that FiND is a useful
focusing framework for the scalable analysis of point-like emitters in biology,
material science, and quantum optics.Comment: 17 pages, 7 figure
Hybrid Plasmonic Bullseye Antennas for Efficient Photon Collection
We
propose highly efficient hybrid plasmonic bullseye antennas
for collecting photon emission from nm-sized quantum emitters. In
our approach, the emitter radiation is coupled to surface plasmon
polaritons that are consequently converted into highly directional
out-of-plane emission. The proposed configuration consists of a high-index
titania bullseye grating separated from a planar silver film by a
thin low-index silica spacer layer. Such hybrid systems are theoretically
capable of directing 85% of the dipole emission into a 0.9 NA objective,
while featuring a spectrally narrow-band tunable decay rate enhancement
of close to 20 at the design wavelength. Hybrid antenna structures
were fabricated by standard electron-beam lithography without the
use of lossy adhesion layers that might be detrimental to antenna
performance. The fabricated antennas remained undamaged at saturation
laser powers exhibiting stable operation. For experimental characterization
of the antenna properties, a fluorescent nanodiamond containing multiple
nitrogen vacancy centers (NV-center) was deterministically placed
in the bullseye center, using an atomic force microscope. Probing
the NV-center fluorescence we demonstrate resonantly enhanced, highly
directional emission at the design wavelength of 670 nm, whose characteristics
are in excellent agreement with our numerical simulations
Ultrabright Room-Temperature Sub-Nanosecond Emission from Single Nitrogen-Vacancy Centers Coupled to Nanopatch Antennas
Ultrabright Room-Temperature Sub-Nanosecond Emission from Single Nitrogen-Vacancy Centers Coupled to Nanopatch Antennas
Solid-state
quantum emitters are in high demand for emerging technologies
such as advanced sensing and quantum information processing. Generally,
these emitters are not sufficiently bright for practical applications,
and a promising solution consists in coupling them to plasmonic nanostructures.
Plasmonic nanostructures support broadband modes, making it possible
to speed up the fluorescence emission in room-temperature emitters
by several orders of magnitude. However, one has not yet achieved
such a fluorescence lifetime shortening without a substantial loss
in emission efficiency, largely because of strong absorption in metals
and emitter bleaching. Here, we demonstrate ultrabright single-photon
emission from photostable nitrogen-vacancy (NV) centers in nanodiamonds
coupled to plasmonic nanocavities made of low-loss single-crystalline
silver. We observe a 70-fold difference between the average fluorescence
lifetimes and a 90-fold increase in the average detected saturated
intensity. The nanocavity-coupled NVs produce up to 35 million photon
counts per second, several times more than the previously reported
rates from room-temperature quantum emitters