Mechanical resonators are ubiquitous in modern information technology. With the possibility of coupling them to electromagnetic and plasmonic modes, they hold promise as the key building blocks in ...future quantum information technology. Graphene-based resonators are of interest for technological applications due to their high resonant frequencies, multiple mechanical modes and low mass. The tension-mediated nonlinear coupling between various modes of the resonator can be excited in a controllable manner. Here we engineer a graphene resonator with large frequency tunability at low temperatures, resulting in a large intermodal coupling strength. We observe the emergence of new eigenmodes and amplification of the coupled modes using red and blue parametric excitation, respectively. We demonstrate that the dynamical intermodal coupling is tunable. A cooperativity of 60 between two resonant modes of ∼100 MHz is achieved in the strong coupling regime. The ability to dynamically control the coupling between the high-frequency eigenmodes of a mechanical system opens up the possibility of quantum mechanical experiments at low temperatures.
Optically addressable spins associated with defects in wide-bandgap semiconductors are versatile platforms for quantum information processing and nanoscale sensing, where spin-dependent inter-system ...crossing transitions facilitate optical spin initialization and readout. Recently, the van der Waals material hexagonal boron nitride (h-BN) has emerged as a robust host for quantum emitters, promising efficient photon extraction and atom-scale engineering, but observations of spin-related effects have remained thus far elusive. Here, we report room-temperature observations of strongly anisotropic photoluminescence patterns as a function of applied magnetic field for select quantum emitters in h-BN. Field-dependent variations in the steady-state photoluminescence and photon emission statistics are consistent with an electronic model featuring a spin-dependent inter-system crossing between triplet and singlet manifolds, indicating that optically-addressable spin defects are present in h-BN.
Abstract
A cobalt‐catalyzed, N,O‐bidentate directing group‐assisted C−H bond functionalization of benzamides with maleimides was developed for the facile access to isoindolone spirosuccinimides in ...good to excellent yields. This C−H bond activation and spirocyclization employing pyridine N‐oxide as directing group provided very good substrate scope and tolerated various functional groups. Furthermore, the mechanistic investigation revealed that the C−H bond activation is the rate‐determining step of this reaction.
A palladium-catalyzed chelation-assisted direct aldehyde C–H bond amidation of quinoline-8-carbaldehydes with an amine was developed under mild reaction conditions. A wide range of amides were ...obtained in good to excellent yields from aldehyde with a variety of aniline derivatives and aliphatic amines. Our methodology was successfully applied to synthesize known DNA intercalating agents and can be easily scaled up to a gram scale.
Milled nanodiamonds containing nitrogen-vacancy (NV) centers are nanoscale quantum sensors that form colloidal dispersions. However, variations in their size, shape, and surface chemistry limit the ...ability to position individual nanodiamonds and statistically study properties that affect their optical and quantum characteristics. Here, we present a scalable strategy to form ordered arrays of nanodiamonds using capillary-driven, template-assisted self-assembly. We demonstrate the precise spatial arrangement of isolated nanodiamonds with diameters below 50 nm across millimeter-scale areas. Measurements of over 200 assembled nanodiamonds yield a statistical understanding of their structural, optical, and quantum properties. The NV centers’ spin and charge properties are uncorrelated with nanodiamond size but rather are consistent with heterogeneity in their nanoscale environment.
Abstract
Bribery for access to public goods and services remains a widespread and seemingly innocuous practice which disproportionately targets the poor and helps keep them poor. Furthermore, its ...aggregate effects erode the legitimacy of government institutions and their capacity to fairly administer public goods and services as well as protection under the law. Drawing on original evidence using social norms methodology, this research tests underlying beliefs and expectations which sustain persistent forms of bribery and draws attention to the presence of pluralistic ignorance and consequent collective action problems. With examples focused on bribery in traffic law enforcement, healthcare, and education—three critical areas where bribery is often identified as an entrenched practice—this article contributes new evidence of: (a) the presence of pluralistic ignorance, a common social comparison error, surrounding bribery behavior; (b) differing social evaluations of bribe-solicitation; and finally, (c) how this context might exacerbate collective action problems. This empirical case study of Nigeria shows that even though more people are likely to be directly affected by bribery during routine interactions with public officials and institutions and many believe this practice is wrong, most people incorrectly believe that others in their community tolerate or even accept bribery behavior.
Hexagonal boron nitride (h-BN) hosts pure single-photon emitters that have shown evidence of optically detected electronic spin dynamics. However, the electrical and chemical structures of these ...optically addressable spins are unknown, and the nature of their spin-optical interactions remains mysterious. Here, we use time-domain optical and microwave experiments to characterize a single emitter in h-BN exhibiting room temperature optically detected magnetic resonance. Using dynamical simulations, we constrain and quantify transition rates in the model, and we design optical control protocols that optimize the signal-to-noise ratio for spin readout. This constitutes a necessary step toward quantum control of spin states in h-BN.
Defect-based quantum emitters in solid-state materials offer a promising platform for quantum communication and sensing. Confocal fluorescence microscopy techniques have revealed quantum emitters in ...a multitude of host materials. The ability to quickly and accurately survey emitter ensembles is important for characterizing these new quantum emitter systems. In some materials, however, optical properties vary widely among emitters, even within the same sample. In these cases, traditional ensemble fluorescence measurements are confounded by heterogeneity, whereas individual defect-by-defect studies are impractical. Here we describe a method to quantitatively and systematically analyze the properties of heterogeneous emitter ensembles using large-area photoluminescence maps. We apply this method to study the effects of sample treatments on emitters in hexagonal boron nitride, and we find that low-energy (3 keV) electron irradiation creates emitters, whereas high-temperature (850 °C) annealing in an inert gas environment brightens emitters.
PURPOSE:To describe the successful use of a technique involving amniotic membrane graft for the repair of leaking cystic blebs following mitomycin C (MMC) trabeculectomy.
PATIENTS AND METHODS:A ...retrospective review of 17 eyes of 16 patients who had undergone trabeculectomy with MMC or combined cataract phacoemulsification and trabeculectomy with MMC and presented with leaky cystic blebs with or without hypotony was conducted. All patients were treated with amniotic membrane graft over the leaking area with conjunctival advancement without excision of the cystic bleb and had a minimum of 1-year follow-up. Success was defined as a final intraocular pressure (IOP) ≥6 and ≤21 mm Hg without glaucoma medications. Qualified success that met the above criteria, however, required the use of glaucoma medication for optimal IOP control. Failure was defined as any patient with persistent bleb leak requiring additional procedures and/or the presence of hypotony (IOP<6 mm Hg±clinical evidence of hypotony maculopathy).
RESULTS:Seventeen of the 17 eyes had complete resolution of bleb leak at last follow-up. Total success rate was 15 of the 17 patients, or 88%. Eleven eyes (64.7%) met criteria for complete success. Four eyes (23.5%) required glaucoma medications after the procedure and met criteria for qualified success. Two eyes (11.8%) met criteria for failure, as they presented with a pinpoint limbal leak requiring a suture at the slit lamp in the postoperative period. Mean IOP increased from 5.7±2.8 mm Hg preoperatively to 13.1±3.4 mm Hg at most recent follow-up (P<0.000007). LogMAR visual acuity likewise improved from 0.7±0.8 preoperatively to 0.1±0.1 LogMAR units at most recent follow-up (P<0.030). Mean follow-up time was 21.4±7.3 months.
CONCLUSIONS:The technique of amniotic membrane bleb draping with conjunctival advancement successfully restored bleb function, while facilitating fast resolution and stabilization of IOP and visual acuity.
Photon-emission-correlation spectroscopy is an indispensable tool for the study of atoms, molecules, and, more recently, solid-state quantum defects. In solid-state systems, its most common use is as ...an indicator of single-photon emission, a key property for quantum technology. Beyond the single-photon purity of an emitter, however, photon-correlation measurements can provide a wealth of information that can reveal details about its electronic structure and optical dynamics that are hidden by other spectroscopy techniques. This tutorial presents a standardized framework for using photon-emission-correlation spectroscopy to study quantum emitters, including discussion of theoretical background, considerations for data acquisition and statistical analysis, and interpretation. We highlight important nuances and best practices regarding the commonly used g^{(2)}(τ=0)<0.5 test for single-photon emission. Finally, we illustrate how this experimental technique can be paired with optical-dynamics simulations to formulate an electronic model for unknown quantum emitters, enabling the design of quantum control protocols and assessment of their suitability for quantum information science applications.
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