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Quantum information processing—which relies on spin defects or single-photon emission—has shown quantum advantage in proof-of-principle experiments including microscopic imaging of electromagnetic fields, strain and temperature in applications ranging from battery research to neuroscience. However, critical gaps remain on the path to wider applications, including a need for improved functionalization, deterministic placement, size homogeneity and greater programmability of multifunctional properties. Colloidal semiconductor nanocrystals can close these gaps in numerous application areas, following years of rapid advances in synthesis and functionalization. In this Review, we specifically focus on three key topics: optical interfaces to long-lived spin states, deterministic placement and delivery for sensing beyond the standard quantum limit, and extensions to multifunctional colloidal quantum circuits. This Review highlights the current potential for colloidal quantum dots for applications in quantum sensing and quantum circuits.

Quantum dot and well architectures are attractive for infrared optoelectronics, and have led to the realization of compelling light sensors. However, they require well-defined passivated interfaces and rapid charge transport, and this has restricted their efficient implementation to costly vacuum-epitaxially grown semiconductors. Here we report solution-processed, sensitive infrared field-emission photodetectors. Using quantum-dots-in-perovskite, we demonstrate the extraction of photocarriers via field emission, followed by the recirculation of photogenerated carriers. We use in operando ultrafast transient spectroscopy to sense bias-dependent photoemission and recapture in field-emission devices. The resultant photodiodes exploit the superior electronic transport properties of organometal halide perovskites, the quantum-size-tuned absorption of the colloidal quantum dots and their matched interface. These field-emission quantum-dot-in-perovskite photodiodes extend the perovskite response into the short-wavelength infrared and achieve measured specific detectivities that exceed 10 12 Jones. The results pave the way towards novel functional photonic devices with applications in photovoltaics and light emission. Efficient implementation of quantum dot and well architectures are restricted to costly vacuum-epitaxially-grown semiconductors. The authors use quantum dots in perovskite to build field-emission photodiodes that are sensitive across the visible and into the short-wavelength infrared.

The light-driven generation of H ₂, the reductive side of water splitting, requires a light absorber or photosensitizer (PS) for electron-hole creation and photoinduced electron transfer. To increase the effectiveness of charge transfer chromophores as PSs, this report describes the attachment of a strongly absorbing organic dye (dipyrromethene-BF ₂, commonly known as Bodipy) to Pt diimine dithiolate charge transfer chromophores and examination of systems containing these dyads for the light-driven generation of H ₂. The use of these dyads increases system activity under green light irradiation (530 nm) relative to systems with either chromophore alone, validating such an approach in designing artificial photosynthetic systems. One dyad system exhibits both high activity and substantial durability (40,000 turnovers relative to PSs over 12 d). New dyads consisting of a strongly absorbing Bodipy (dipyrromethene-BF ₂) dye and a platinum diimine dithiolate (PtN ₂S ₂) charge transfer (CT) chromophore have been synthesized and studied in the context of the light-driven generation of H ₂ from aqueous protons. In these dyads, the Bodipy dye is bonded directly to the benzenedithiolate ligand of the PtN ₂S ₂ CT chromophore. Each of the new dyads contains either a bipyridine (bpy) or phenanthroline (phen) diimine with an attached functional group that is used for binding directly to TiO ₂ nanoparticles, allowing rapid electron photoinjection into the semiconductor. The absorption spectra and cyclic voltammograms of the dyads show that the spectroscopic and electrochemical properties of the dyads are the sum of the individual chromophores (Bodipy and the PtN ₂S ₂ moieties), indicating little electronic coupling between them. Connection to TiO ₂ nanoparticles is carried out by sonication leading to in situ attachment to TiO ₂ without prior hydrolysis of the ester linking groups to acids. For H ₂ generation studies, the TiO ₂ particles are platinized (Pt-TiO ₂) so that the light absorber (the dyad), the electron conduit (TiO ₂), and the catalyst (attached colloidal Pt) are fully integrated. It is found that upon 530 nm irradiation in a H ₂O solution (pH 4) with ascorbic acid as an electron donor, the dyad linked to Pt-TiO ₂ via a phosphonate or carboxylate attachment shows excellent light-driven H ₂ production with substantial longevity, in which one particular dyad [4(bpyP)] exhibits the highest activity, generating ∼40,000 turnover numbers of H ₂ over 12 d (with respect to dye).

A special perovskite material design is demonstrated to operate as a wideband, achromatic quarter-wave plate.

Lead halide perovskites (LHPs) have become a promising alternative for a wide range of optoelectronic devices, thanks to their solution‐processability and impressive optical and electrical properties. More recently, LHPs have been investigated in magneto‐optic studies and have exhibited spin‐polarized emission, photoinduced magnetization, and long spin lifetimes. Here, the viability of methylammonium lead bromide (MAPbBr3) single crystals as solution‐processed Faraday rotators is demonstrated. Compared to terbium gallium garnet, the industry standard in the visible, it is found that MAPbBr3 exhibits Verdet constants (i.e., strength of Faraday effect) of similar or greater magnitude (up to 2.5x higher), with lower temperature dependence. Due to its low trap absorption, it is calculated that an optical isolator made from MAPbBr3, with appropriate antireflection coatings, should reach ≈95% transmission and achieve 40 dB isolation for incoming powers of over 2 W. It is also shown that the Verdet constant of MAPbBr3 can be calculated accurately from its dispersion in refractive index, allowing the possibility to predict similar effects in other perovskite materials. Strong Faraday rotation is demonstrated for methylammonium lead bromide (MAPbBr3) single crystals. Coupled with low defect density, they are poised to represent a solution‐processed alternative for Faraday rotator applications, such as optical isolators and optical switches. Additionally, their Faraday rotation fits well with classical theory, allowing prediction of other perovskites for this application.

By switching shell growth on and off on the (0001) facet of wurtzite CdSe cores to produce a built-in biaxial strain that lowers the optical gain threshold, we achieve continuous-wave lasing in colloidal quantum dot films. SQUEEZED LIGHT The electronic structure of colloidal quantum dots lends them a host of desirable optical properties, but they typically perform poorly as laser materials. Fengjia Fan et al. have developed a scheme for tuning this electronic structure in such a way that the barriers to laser action might be overcome. Specifically, they developed a synthesis strategy in which the shell of material encompassing the core of the quantum dot is asymmetric and compressive. This effectively squeezes the particle, thereby modifying the electronic structure to favour laser-like emissions. Colloidal quantum dots (CQDs) feature a low degeneracy of electronic states at the band edges compared with the corresponding bulk material 1 , as well as a narrow emission linewidth 2 , 3 . Unfortunately for potential laser applications, this degeneracy is incompletely lifted in the valence band, spreading the hole population among several states at room temperature 4 , 5 , 6 . This leads to increased optical gain thresholds, demanding high photoexcitation levels to achieve population inversion (more electrons in excited states than in ground states—the condition for optical gain). This, in turn, increases Auger recombination losses 7 , limiting the gain lifetime to sub-nanoseconds and preventing steady laser action 8 , 9 . State degeneracy also broadens the photoluminescence linewidth at the single-particle level 10 . Here we demonstrate a way to decrease the band-edge degeneracy and single-dot photoluminescence linewidth in CQDs by means of uniform biaxial strain. We have developed a synthetic strategy that we term facet-selective epitaxy: we first switch off, and then switch on, shell growth on the (0001) facet of wurtzite CdSe cores, producing asymmetric compressive shells that create built-in biaxial strain, while still maintaining excellent surface passivation (preventing defect formation, which otherwise would cause non-radiative recombination losses). Our synthesis spreads the excitonic fine structure uniformly and sufficiently broadly that it prevents valence-band-edge states from being thermally depopulated. We thereby reduce the optical gain threshold and demonstrate continuous-wave lasing from CQD solids, expanding the library of solution-processed materials 11 , 12 that may be capable of continuous-wave lasing. The individual CQDs exhibit an ultra-narrow single-dot linewidth, and we successfully propagate this into the ensemble of CQDs.

Colloidal quantum dots (CQDs) are a promising gain material for solution-processed, wavelength-tunable lasers, with potential application in displays, communications, and biomedical devices. In this work, we combine a CQD film with an array of titanium dioxide (TiO2) nanoantennas to achieve lasing via bound states in the continuum (BICs), which are symmetry-protected cavity modes with giant quality factors. Here, the BICs arise from slab waveguide modes in the planar film, coupled to the periodic nanoantenna array. We engineer the thickness of the CQD film and size of the nanoantennas to achieve a BIC with good spatial and spectral overlap with the CQDs, based on a 2nd-order TE-polarized waveguide mode. We obtain room-temperature lasing with a low threshold of approximately 11 kW/cm2 (peak intensity) under 5 ns-pulsed optical excitation. This work sheds light on the optical modes in solution-processed, distributed-feedback lasers, and highlights BICs as effective, versatile, surface-emitting lasing modes.

The TGFβ cytokine family member, GDF-15, reduces food intake and body weight and represents a potential treatment for obesity. Because the brainstem-restricted expression pattern of its receptor, GDNF Family Receptor α–like (GFRAL), presents an exciting opportunity to understand mechanisms of action for area postrema neurons in food intake; we generated GfralCre and conditional GfralCreERT mice to visualize and manipulate GFRAL neurons. We found infection or pathophysiologic states (rather than meal ingestion) stimulate GFRAL neurons. TRAP-Seq analysis of GFRAL neurons revealed their expression of a wide range of neurotransmitters and neuropeptides. Artificially activating GfralCre-expressing neurons inhibited feeding, decreased gastric emptying, and promoted a conditioned taste aversion (CTA). GFRAL neurons most strongly innervate the parabrachial nucleus (PBN), where they target CGRP-expressing (CGRPPBN) neurons. Silencing CGRPPBN neurons abrogated the aversive and anorexic effects of GDF-15. These findings suggest that GFRAL neurons link non–meal-associated pathophysiologic signals to suppress nutrient uptake and absorption.

BackgroundThe first Multicenter Medication Reconciliation Quality Improvement (QI) Study (MARQUIS1) demonstrated that mentored implementation of a medication reconciliation best practices toolkit decreased total unintentional medication discrepancies in five hospitals, but results varied by site. The objective of this study was to determine the effects of a refined toolkit on a larger group of hospitals.MethodsWe conducted a pragmatic quality improvement study (MARQUIS2) at 18 North American hospitals or hospital systems from 2016 to 2018. Incorporating lessons learnt from MARQUIS1, we implemented a refined toolkit, offering 17 system-level and 6 patient-level interventions. One of eight physician mentors coached each site via monthly calls and performed one to two site visits. The primary outcome was number of unintentional medication discrepancies in admission or discharge orders per patient. Time series analysis used multivariable Poisson regression.ResultsA total of 4947 patients were sampled, including 1229 patients preimplementation and 3718 patients postimplementation. Both the number of system-level interventions adopted per site and the proportion of patients receiving patient-level interventions increased over time. During the intervention, patients experienced a steady decline in their medication discrepancy rate from 2.85 discrepancies per patient to 0.98 discrepancies per patient. An interrupted time series analysis of the 17 sites with sufficient data for analysis showed the intervention was associated with a 5% relative decrease in discrepancies per month over baseline temporal trends (adjusted incidence rate ratio: 0.95, 95% CI 0.93 to 0.97, p<0.001). Receipt of patient-level interventions was associated with decreased discrepancy rates, and these associations increased over time as sites adopted more system-level interventions.ConclusionA multicentre medication reconciliation QI initiative using mentored implementation of a refined best practices toolkit, including patient-level and system-level interventions, was associated with a substantial decrease in unintentional medication discrepancies over time. Future efforts should focus on sustainability and spread.

BackgroundThe second Multicenter Medication Reconciliation Quality Improvement Study demonstrated a marked reduction in medication discrepancies per patient. The aim of the current analysis was to determine the association of patient exposure to each system-level intervention and receipt of each patient-level intervention on these results.MethodsThis study was conducted at 17 North American Hospitals, the study period was 18 months per site, and sites typically adopted interventions after 2–5 months of preintervention data collection. We conducted an on-treatment analysis (ie, an evaluation of outcomes based on patient exposure) of system-level interventions, both at the category level and at the individual component level, based on monthly surveys of implementation site leads at each site (response rate 65%). We then conducted a similar analysis of patient-level interventions, as determined by study pharmacist review of documented activities in the medical record. We analysed the association of each intervention on the adjusted number of medication discrepancies per patient in admission and discharge orders, based on a random sample of up to 22 patients per month per site, using mixed-effects Poisson regression with hospital site as a random effect. We then used a generalised linear mixed-effects model (GLMM) decision tree to determine which patient-level interventions explained the most variance in discrepancy rates.ResultsAmong 4947 patients, patient exposure to seven of the eight system-level component categories was associated with modest but significant reductions in discrepancy rates (adjusted rate ratios (ARR) 0.75–0.97), as were 15 of the 17 individual system-level intervention components, including hiring, reallocating and training personnel to take a best possible medication history (BPMH) and training personnel to perform discharge medication reconciliation and patient counselling. Receipt of five of seven patient-level interventions was independently associated with large reductions in discrepancy rates, including receipt of a BPMH in the emergency department (ED) by a trained clinician (ARR 0.40, 95% CI 0.37 to 0.43), admission medication reconciliation by a trained clinician (ARR 0.57, 95% CI 0.50 to 0.64) and discharge medication reconciliation by a trained clinician (ARR 0.64, 95% CI 0.57 to 0.73). In GLMM decision tree analyses, patients who received both a BPMH in the ED and discharge medication reconciliation by a trained clinician experienced the lowest discrepancy rates (0.08 per medication per patient).Conclusion and relevancePatient-level interventions most associated with reductions in discrepancies were receipt of a BPMH of admitted patients in the ED and admission and discharge medication reconciliation by a trained clinician. System-level interventions were associated with modest reduction in discrepancies for the average patient but are likely important to support patient-level interventions and may reach more patients. These findings can be used to help hospitals and health systems prioritise interventions to improve medication safety during care transitions.