26 research outputs found
Scalable Focused Ion Beam Creation of Nearly Lifetime-Limited Single Quantum Emitters in Diamond Nanostructures
The controlled creation of defect center---nanocavity systems is one of the
outstanding challenges for efficiently interfacing spin quantum memories with
photons for photon-based entanglement operations in a quantum network. Here, we
demonstrate direct, maskless creation of atom-like single silicon-vacancy (SiV)
centers in diamond nanostructures via focused ion beam implantation with nm lateral precision and nm positioning accuracy relative to a
nanocavity. Moreover, we determine the Si+ ion to SiV center conversion yield
to and observe a 10-fold conversion yield increase by additional
electron irradiation. We extract inhomogeneously broadened ensemble emission
linewidths of GHz, and close to lifetime-limited single-emitter
transition linewidths down to MHz corresponding to -times
the natural linewidth. This demonstration of deterministic creation of
optically coherent solid-state single quantum systems is an important step
towards development of scalable quantum optical devices
Quantum interference of electromechanically stabilized emitters in nanophotonic devices
Photon-mediated coupling between distant matter qubits may enable secure
communication over long distances, the implementation of distributed quantum
computing schemes, and the exploration of new regimes of many-body quantum
dynamics. Nanophotonic devices coupled to solid-state quantum emitters
represent a promising approach towards realization of these goals, as they
combine strong light-matter interaction and high photon collection
efficiencies. However, the scalability of these approaches is limited by the
frequency mismatch between solid-state emitters and the instability of their
optical transitions. Here we present a nano-electromechanical platform for
stabilization and tuning of optical transitions of silicon-vacancy (SiV) color
centers in diamond nanophotonic devices by dynamically controlling their strain
environments. This strain-based tuning scheme has sufficient range and
bandwidth to alleviate the spectral mismatch between individual SiV centers.
Using strain, we ensure overlap between color center optical transitions and
observe an entangled superradiant state by measuring correlations of photons
collected from the diamond waveguide. This platform for tuning spectrally
stable color centers in nanophotonic waveguides and resonators constitutes an
important step towards a scalable quantum network
Aggregation-Induced Emission from FluorophoreâQuencher Dyads with Long-Lived Luminescence
Aggregation-induced emission (AIE)
is an important photophysical
phenomenon in molecular materials and has found broad applications
in optoelectronics, bioimaging, and chemosensing. Currently, the majority
of reported AIE-active molecules are based on either propeller-shaped
rotamers or donorâacceptor molecules with strong intramolecular
charge-transfer states. Here, we report a new design motif, where
a fluorophore is covalently tethered to a quencher, to expand the
scope of AIE-active materials. The fluorophoreâquencher dyad
(FQD) is nonemissive in solutions due to photoinduced electron-transfer
quenching but becomes luminescent in the solid state. The intrinsic
emission lifetimes are found to be within the microseconds domain
at both room and low temperatures. We performed single-crystal X-ray
diffraction measurement for each of the FQDs as well as theoretical
calculations to account for the possible origin of the long-lived
AIE. These FQDs represent a new class of AIE-active molecules with
potential applications in organic optoelectronics
Aromatic Difluoroboron ÎČâDiketonate Complexes: Effects of ÏâConjugation and Media on Optical Properties
Aromatic difluoroboron ÎČ-diketonate complexes (BF<sub>2</sub>bdks) are classic fluorescent molecules that have been explored as photochemical reagents, two-photon dyes, and oxygen sensors. To gain a better understanding of their emissive properties in both solution and polymer matrices, BF<sub>2</sub>bdks with varying aromatic groups were synthesized and their photophysical properties were investigated in both methylene chloride and polyÂ(lactic acid) (PLA). Absorption spectra showed systematic variations that are well correlated with structural features, including the size of the aryl substituent and the presence of a para electron-donating methoxy substituent. Computational modeling of the absorption spectra with the TD-B3LYP/6-311+GÂ(d)//B3LYP/6-31GÂ(d) formulation of density functional theory and a polarizable continuum model of dichloromethane solvent shows that all systems show intense ÏâÏ* one-electron excitations, usually from one of the highest occupied molecular orbitals (HOMO â <i>k</i>, <i>k</i> = 0, 1, 2) to the lowest unoccupied molecular orbital (LUMO). Emission properties are sensitive to the dye structure and medium. Based on spectroscopic and lifetime studies, BF<sub>2</sub>bdks exhibit comparable fluorescence properties in both solutions and polymers when the diketonate group is functionalized with smaller aromatic ring systems such as benzene. For BF<sub>2</sub>bdks with larger arene ring systems, such as anthracene, emission from a strong intramolecular charge-transfer (ICT) state was also noted in both solution and in PLA. There are differences in relative intensities of peaks arising from ÏâÏ* and ICT excitations depending upon dye loading in PLA. Substituent effects were also observed. Electron-donating methoxyl groups on the aromatic rings lead to enhanced fluorescence quantum yields. For certain dyes, phosphorescence is detected at low temperature or under a nitrogen atmosphere in PLA matrices
All-optical nanoscale thermometry with silicon-vacancy centers in diamond
International audienc
Tailoring Oxygen Sensitivity with Halide Substitution in Difluoroboron Dibenzoylmethane Polylactide Materials
Tailoring Oxygen Sensitivity with Halide Substitution in Difluoroboron Dibenzoylmethane Polylactide Materials
The dual-emissive properties of solid-state
difluoroboron ÎČ-diketonate-polyÂ(lactic acid) (BF<sub>2</sub>bdkPLA) materials have been utilized for biological oxygen sensing.
In this work, BF<sub>2</sub>dbmÂ(X)ÂPLA materials were synthesized,
where X = H, F, Cl, Br, and I. The effects of changing the halide
substituent and PLA polymer chain length on the optical properties
in dilute CH<sub>2</sub>Cl<sub>2</sub> solutions and solid-state polymer
films were studied. These luminescent materials show fluorescence,
phosphorescence, and lifetime tunability on the basis of molecular
weight, as well as lifetime modulation via the halide substituent.
Short BF<sub>2</sub>dbmÂ(Br)ÂPLA (6.0 kDa) and both short and long BF<sub>2</sub>dbmÂ(I)ÂPLA polymers (6.0 or 20.3 kDa) have fluorescence and
intense phosphorescence ideal for ratiometric oxygen sensing. The
lighter halide-dye polymers with hydrogen, fluorine, and chlorine
substitution have longer phosphorescence lifetimes and can be utilized
as ultrasensitive oxygen sensors. Photostability was also analyzed
for the polymer films