Spin defects in two-dimensional materials are a promising platform for quantum sensing. Simulating the defect's optical response and optically detected magnetic resonance (ODMR) contrast is key to identifying suitable candidates. However, existing simulation methods are typically unable to supply the required accuracy. Here, we propose two quantum algorithms to detect an imbalance in the triplet-to-singlet intersystem crossing (ISC) rates between excited states with the same and different spin projections, a necessary condition for nonzero ODMR response. The lowest-cost approach evaluates whether the evolution of an S = 0 state under the spin-orbit coupling induces ISC to S = 1, and also whether there is an imbalance in its intensity depending on the final-state spin projection. The second approach works by comparing the emission spectrum of a spin defect with and without the spin-orbit coupling operator, inferring ISC intensity for different spin transition channels from spectrum intensity changes. Additionally, we present an improved scheme to evaluate the defect's optical response, building upon previous work. We study these quantum algorithms in the context of the negatively charged boron vacancy in hexagonal boron nitride. We generate an embedded active space of 18 spatial orbitals using quantum defect embedding theory and show that the ISC rate imbalance can be detected with as few as 105 logical qubits and 4.41 & times; 108 Toffoli gates. By avoiding direct and costly rate calculations, our methods enable faster screening of candidate defects for ODMR activity, advancing the prospect of using quantum simulations to aid the development of high-performing sensing devices.

Despite seamless integration of hexagonal boron nitride (hBN) with on-chip devices, the intrinsically low optical quantum yield of spin-active boron vacancy ( V B - ${\mathrm{V}}_{\mathrm{B}}^ - $ ) defects remains a significant limitation to the sensitivity of hBN-based quantum sensors. Here, we demonstrate an hBN quantum sensor with enhanced quantum yield and high DC magnetic field sensitivity (ηDC), achieved by coupling V B - ${\mathrm{V}}_{\mathrm{B}}^ - $ defects in hBN with a nanostructured plasmon-strain microwave waveguide architecture.This platform is realized by fabricating arrays of alumina-coated gold nanopillars, or plasmonic nanoresonators (PNRs), onto the constricted region of a microwave-efficient, single-port gold coplanar waveguide. The alumina coating acts as a dielectric barrier that suppresses photoluminescence (PL) quenching, while gold nanopillars enhance local electromagnetic fields and induce strain-driven perturbations of the defect energy levels, causing accelerated photo-emission. This synergistic effect results in a ∼tenfold enhancement in PL and improves optically detected magnetic resonance to -17% for on-PNR regions, exceeding comparable prior works by over an order of magnitude. Consequently, we achieve an ηDC of 9.4 µT/√Hz, approaching the highest reported values for V B - ${\mathrm{V}}_{\mathrm{B}}^ - $ defects. This research establishes a strategy for designing and fabricating highly sensitive quantum sensors that operate at room temperature without requiring extensive optimization of laser or microwave fields.

Spin defects in hexagonal boron nitride (hBN) are emerging platforms for quantum sensing. The negatively charged boron vacancy (VB-) is widely studied due to its robust spin properties, but its low brightness often requires plasmonic enhancement, limiting sensing in optically opaque or scattering environments, such as batteries. Here, we design and nanofabricate a coplanar waveguide integrated with nanoslit arrays to enable back-side excitation and photoluminescence collection from hBN spin defects. Using a neon focused ion beam, we pattern periodic nanoslits through a thin gold film, allowing simultaneous microwave delivery and optical access through the substrate. We demonstrate device performance via T1 relaxometry and magnetic field mapping of nickel nanoparticles. This platform enables plasmonically enhanced quantum sensing in opaque materials and liquids, expanding applications beyond conventional transparent systems.

Spin defects in two-dimensional materials are a promising platform for quantum sensing. Simulating the defect's optical response and optically detected magnetic resonance (ODMR) contrast is key to identifying suitable candidates. However, existing simulation methods are typically unable to supply the required accuracy. Here, we propose two quantum algorithms to detect an imbalance in the triplet-to-singlet intersystem crossing (ISC) rates between excited states with the same and different spin projections – a necessary condition for nonzero ODMR response. The lowest-cost approach evaluates whether the evolution of an S=0 state under the spin-orbit coupling induces ISC to S=1, and also whether there is an imbalance in its intensity depending on the final state spin projection. The second approach works by comparing the emission spectrum of a spin defect with and without the spin-orbit coupling operator, inferring ISC intensity for different spin transition channels from spectrum intensity changes. Additionally, we present an improved scheme to evaluate the defect's optical response, building upon previous work. We study these quantum algorithms in the context of the negatively charged boron vacancy in hexagonal boron nitride. We generate an embedded active space of 18 spatial orbitals using quantum defect embedding theory (QDET) and show that the ISC rate imbalance can be detected with as few as 105 logical qubits and 2.2 × 10^8 Toffoli gates. By avoiding direct and costly rate calculations, our methods enable faster screening of candidate defects for ODMR activity, advancing the prospect of using quantum simulations to aid the development of high-performing sensing devices.

The past decade has witnessed a growing research interest in quantum sensing using spin-active boron vacancy (VB-) defects in hexagonal boron nitride (hBN). While hBN enables easy chip integration, current quantum sensing devices suffer from low optical readout and noisy signals due to inefficient waveguide designs that limit microwave absorption, resulting in reduced optically detected magnetic resonance (ODMR) contrast. This study advances hBN-integrated quantum sensors through three generations, culminating in a compact single-port coplanar waveguide (CPW). Unlike conventional two-port waveguides, our design allows on-chip optical and microwave excitation, ensuring improved impedance stability and high radio frequency (RF) magnetic field concentration without altering spin properties. As a result, we achieve a high ODMR contrast of ∼28% at low microwave power (MW) of 400 mW. This miniaturized sensor enhances efficiency three times, reduces the use of RF power to five times, and supports robust performance at lower MW power, making it ideal for scalable quantum sensing applications such as magnetic field detection.

It is known that total absorption of flexural waves in a thin beam is possible through the use of monopole-dipole scatterers. In this study, we introduce a pair of identical monopole scatterers for near-total absorption of flexural waves in a thin and wide beam. Despite the two scatterers being both of the monopole type, the resonant modes of the scatterer pair exhibit monopole and dipole properties. By selecting the proper width for the beam, the two resonant modes degenerate, which leads to the total absorption. Although the beam is considerably wide, the frequency range of interest remains below the cut-on frequency of the n = 1 propagating mode, ensuring one-dimensional flexural wave propagation. Further simulations and theoretical analysis revealed that the degeneracy of the monopole and dipole modes results from their interaction with a higher-order localized flexural mode. The simulation results demonstrate absorption exceeding 99%, complemented by experimental data showing approximately 90% absorption.

There is a pressing need for more accurate computational simulations of the optoelectronic properties of defects in materials to aid in the development of quantum sensing platforms. In this work, we explore how quantum computers could be effectively utilized for this purpose. Specifically, we develop fault-tolerant quantum algorithms to simulate optically active defect states and their radiative emission rates. We employ quantum defect embedding theory to translate the Hamiltonian of a defect-containing supercell into a smaller, effective Hamiltonian that accounts for dielectric screening effects. Our approach integrates block-encoding of the dipole operator with quantum phase estimation to selectively sample the optically active excited states that exhibit the largest dipole transition amplitudes. We also provide estimates of the quantum resources required to simulate a negatively charged boron vacancy in a hexagonal boron nitride cluster. We conclude by offering a forward-looking perspective on the potential of quantum computers to enhance quantum sensor capabilities and identify specific scenarios where quantum computing can resolve problems traditionally challenging for classical computers.

This paper provides a comprehensive review of quantum spin sensing with a focus on the nitrogen vacancy (NV) center in diamond. Beginning with the discovery of optically detected magnetic resonance in NV centers, we trace the evolution of this technology and its integration with complementary metal-oxide-semiconductor technology, marking a significant advancement in measurement science. The unique optical and spin properties of NV centers, operational at room temperature and under ambient conditions, have broadened their application spectrum, notably in magnetometry for nanoscale magnetic field detection. This work describes the transition from isolated NV centers to dense ensembles, highlighting the challenges and advancements in microfabrication and nanofabrication that have facilitated the integration of these centers with photonic structures and electronic devices. The efficient readout of NV spin states and the challenges in miniaturization are addressed, showcasing the development of compact, portable quantum sensors. We also discuss the potential impact of these sensors in various domains, including vehicle sensor systems and biomedical applications, underscoring the significance of environmental influences on magnetometric readings.

High temperature (HT) (around 120-200°C) PEM FCs are predicted to be the next generation of PEMFCs particularly for hydrogen-powered automobiles and combined heat and power (CHP) systems because the water management can be simplified at such temperatures as only a single phase of water vapor needs to be considered. Additionally, the cooling system can be streamlined due to an increase in temperature gradient between the coolant and the FC stack. This will also allow easy recovery of waste heat that can be used as a practical heat source. Furthermore, the CO tolerance improves dramatically at high temperatures thereby allowing HT PEMFCs to utilize reformed and impure hydrogen. A single phase three-dimensional, steady-state, isothermal model for a single 5 HT PEM fuel cell with serpentine flow channels is implemented in COMSOL to investigate the effect of various operating conditions like temperature, back pressure and cathode flow rate and design parameters like catalyst layer loading, cathode GDL porosity, and flow field channels including parallel and interdigitated channels. Different performance indicators in terms of polarization curve, loss mechanisms, oxygen molar concentration, and anode and cathode pressure are represented for a complete overall analysis. In fact, the breakdown of different overpotential loss mechanism for HT PEMFC presented here is unique that not only quantifies these losses but also provides an accurate comparison with corresponding low temperature counterpart. The result from the computational model follows the experimental result very closely, thus, validating our model. The simulations stipulates that the performance of a HT PEMFC improves with increasing temperature, back pressure, and air flow rate. Increasing catalyst layer loading improves the performance up to a point after which it starts to drop at low voltages because of hindered gas diffusion. Similarly, a comparative study among different flow field channel is also presented indicating improved performance when going from parallel to interdigitated and serpentine channels. Furthermore, this study provides guidelines to optimize HT PEMFC performance through comprehensive parametric study.

Sluggish oxygen evolution reaction (OER) in acid conditions is one of the bottlenecks that prevent the wide adoption of proton exchange membrane water electrolyzer for green hydrogen production. Despite recent advancements in developing high-performance catalysts for acid OER, the current electrocatalysts still rely on iridium- and ruthenium-based materials, urging continuous efforts to discover better performance catalysts as well as reduce the usage of noble metals. Pyrochlore structured oxide is a family of potential high-performance acid OER catalysts with a flexible compositional space to tune the electrochemical capabilities. However, exploring the large composition space of pyrochlore compounds demands an imperative approach to enable efficient screening. Here we present a high-throughput screening pipeline that integrates density functional theory calculations and a transfer learning approach to predict the critical properties of pyrochlore compounds. The high-throughput screening recommends three sets of candidates for potential acid OER applications, totaling 61 candidates from 6912 pyrochlore compounds. In addition to 3d-transition metals, p-block metals are identified as promising dopants to improve the catalytic activity of pyrochlore oxides. This work demonstrates not only an efficient approach for finding suitable pyrochlores towards acid OER but also suggests the great compositional flexibility of pyrochlore compounds to be considered as a new materials platform for a variety of applications.

In recent years, low-temperature polymer electrolyte membrane fuel cells (PEMFCs) have played an increasingly important role in zero emission strategy to halt climate change. The performance improvement is a particular focus of fuel cell research and development, with water management being one of the major areas of interest. Here we report the development of a novel metal foam gas diffusion layer (GDL) material with embedded gas flow channels. Owing to the porous nature of the gas channel walls, the membrane electrode assembly (MEA) performance is significantly improved as a result of enhanced mass transport. Unprecedented high power density of 2.09 W/cm2 was observed at 90% relative humidity, and 2.04 W/cm2 for 149% relative humidity, which are respectively 12% and 37% improvement over current state-of-the-art low temperature PEMFC performance. Furthermore, we demonstrated that with our metal foam GDL, it is possible to simplify the flow field design on the bipolar plate, leading to manufacturing cost reduction of the fuel cell components. The work provides new pathway to achieve both high performance and low cost for fuel cells, water electrolyzers and other related technologies.

Active acoustic metamaterials incorporate electric circuit elements that input energy into an otherwise passive medium to aptly modulate the effective material properties. Here, we propose an active acoustic metamaterial with Willis coupling to drastically extend the tunability of the effective density and bulk modulus with the accessible parameter range enlarged by at least two orders of magnitude compared to that of a non-Willis metamaterial. Traditional active metamaterial designs are based on local resonances without considering the Willis coupling that limit their accessible effective material parameter range. Our design adopts a unit cell structure with two sensor-transducer pairs coupling the acoustic response on both sides of the metamaterial by detecting incident waves and driving active signals asymmetrically superimposed onto the passive response of the material. The Willis coupling results from feedback control circuits with unequal gains. These asymmetric feedback control circuits use Willis coupling to expand the accessible range of the effective density and bulk modulus of the metamaterial. The extreme effective material parameters realizable by the metamaterials will remarkably broaden their applications in biomedical imaging, noise control, and transformation acoustics-based cloaking.

Multicomponent alloys and oxides are material systems, offering the great promise of unique yet advantageous catalytic properties through appropriate choice of compositions. However, strategic design of the highly active multicomponent catalyst is challenged by the vast number of potential candidates and complex inter-component effects. Herein, we demonstrate the successful employment of Bayesian optimization (BO) to improve the experimental measured activity as a direct function of compositional variables without educating physical knowledge to the machine. We applied BO in screening spinel CraMnbFecCodNieCufZn3-a-b-c-d-e-fO4 for the decomposition of nitric oxide into environmentally friendly nitrogen. Starting with 30 manually surveyed samples, 35 more samples were measured, and six oxides were discovered with higher specific activities. The best candidate discovered in the current work, Co2.1Cu0.6Zn0.2Mn0.1O4, showed significantly better catalytic performance than the benchmark standard. Although not directly educated about the underlying physical origin of variation in specific activity, the optimization balanced the exploration to locate promising regions and exploitation to survey in the identified region of Mn-containing subspace. The success to directly optimize the experimental measured specific activity in the large compositional space through a small sampled data set demonstrates the great potential of BO in the discovery and design of multicomponent catalysts.

Willis coupling, also known as pressure-velocity cross coupling, in acoustic materials has received much attention in the past years. This effect has been found useful in acoustic metasurface designs for wave redirection. We find that Willis coupling in phononic crystals also provides rich physics to manipulate waves. Here, we report the extreme asymmetric lateral sound beaming effect in a two-dimensional phononic crystal composed of Willis scatterers. By matching the second-order Bragg scattering with two leaky guided modes (a quadrupole resonance and a cross-coupling-induced dipole resonance), a normally incident wave is redirected towards the positive and negative directions orthogonal to the incident wave with different amounts of energy. Simulation and experimental results demonstrate the extraordinary asymmetric lateral beaming effect in the Willis medium. The results presented here may find applications in the design of tunable beam splitters and waveguides.

Optical invisibility, which started in the pages of fiction before becoming an intriguing quest of humankind for over a century, has blossomed into a remarkable scientific journey toward reality over the last two decades. Perfect optical cloaking requires the total scattering of electromagnetic waves around an object at all angles, all polarizations, over a wide frequency range, irrespective of the medium. Such a device is still far-fetched, requiring the transformation of space around a cloaked region such that the phase velocity is faster than other areas to preserve the phase relationships. However, by simplifying the invisibility requirements, pioneering work on spherical transformation cloaks, carpet cloaks, plasmonic cloaks, and mantle cloaks has been realized in narrowband microwave, infrared, and even optical wavelengths. In this Tutorial, we review the theoretical basis for invisibility cloaking, from spherical transformational optics to non-Euclidian cases, and discuss their limitations. Subsequently, we highlight the recent trends in realizing reconfigurable intelligent cloaks to overcome the traditional limitations of wideband operation and parallel efforts in unidirectional cloaking. Because the human eye is insensitive to the phase and polarization of visible light, a class of ray optics cloaking devices has been recently developed by eliminating phase preservation requirements. Notably, we focus on the recent progress achieved on invisibility cloaks that function in natural incoherent light and can be realized using standard optical components. We conclude this Tutorial with a prospective of potential applications and the practicality of optical cloaks in everyday life.

INTRODUCTION: Mucormycosis is a potentially fatal fungal infection that often infects patients who are immunocompromised.We present a case of pulmonary mucormycosis in a young patient admitted for a new diagnosis of diabetes in the form of diabetic ketoacidosis (DKA).CASE REPORT: A 21-year-old man with no medical history presented to the Emergency Department in February 2020, with fevers, dyspnea, cough and pleuritic chest pain.He was tachycardic, febrile and had left sided rales on lung auscultation.Labs were consistent with DKA with leukocytosis.Chest X-Ray, confirmed by computed tomography, showed a consolidative opacity in the left lower lobe.He was admitted and treated for DKA and community acquired pneumonia.He had persistent fevers and worsening consolidative opacities.Antibiotics were broadened and pulmonary and infectious disease services were consulted.Negative microbiological testing included a viral respiratory panel, blood cultures, and urine legionella antigen.Sputum culture grew 2+ mixed respiratory flora.Two sputum samples had negative acid-fast bacilli smear and tuberculosis polymerase chain reaction.HIV antibody, serum 1,3-beta-D glucan and galactomannan assays were negative.He was placed on airborne precautions and tested for SARS-CoV 2. Bronchoscopy was deferred pending this result.He developed erythema on his right flank and punch biopsy was performed on hospital day 10 which grew mold.A bronchoscopy showed markedly necrotic and devitalized endobronchial tissue (Figure).Washings and endobronchial biopsies were notable for non-septate fungal hyphae with irregular branching.The patient was started on IV liposomal amphotericin and underwent urgent left lower lobectomy.Pathology demonstrated multiple tan-white firm nodules, thrombus obstructing the main vessels and red hepatization of the entire lobe.Further staining revealed acute fungal bronchopneumonia with angioinvasion, vascular thrombi and associated parenchymal infarction.Fungal organisms morphologically consistent with Mucorales were identified.He subsequently had sharp debridement of the right flank lesion.The patient was discharged home on day 24 with intravenous amphotericin B to continue for at least 3 months.DISCUSSION: Mucormycosis should be considered in a patient with progressive pulmonary opacities despite broad spectrum antibiotic administration.Patterns of involvement include rhinocerebral, pulmonary, cutaneous, and disseminated infection.Risk factors include uncontrolled diabetes mellitus, immunosuppression, and deferoxamine therapy.No predisposing condition is identified in 18% of patients.Prophylaxis with voriconazole and echinocandins does not prevent mucormycosis infection.Beta-D glucan and galactomannan antigens are usually normal.Treatment involves antifungal drugs and aggressive resection of affected tissue.

Willis materials or bianisotropic acoustic materials that couples pressure to particle velocity provide rich physics for sound manipulation. It has recently been shown that tailored Willis acoustic scatterers with resonance effects can display significant cross-coupling between the monopole and dipole responses. In this talk, we show that the multiple scattering in a bianisotropic phononic crystal composed of Willis acoustic scatterers also leads to interesting coupling behavior. The asymmetric structure in our design is non-resonant in the frequency range of interest. However, the nonlocal effect due to the multiple scattering among the scatterers leads to coupling between quadrupole and dipole responses. The phononic crystal is tuned to match the second-order Bragg scattering with two leaky guided modes. We show that a normally incident wave can be steered to propagate along the positive and negative directions perpendicular to the incident direction with different amounts of energy. Simulation and experimental results will be discussed.

Light detection and ranging (LiDAR) systems are becoming crucial for measuring the distance and creating a point cloud of the local environment, critical data for artificial intelligence to enable collision‐avoidance mechanisms. However, LiDAR utilizes radiation in the near‐infrared (NIR) region of the electromagnetic spectrum, which is prone to complete absorption by typical dark (such as painted by carbon black) colored objects, leading to loss of timely data points. Till date a very limited number of solutions have been put forward to address this. Herein, nanocrystallites of copper (II) oxide with specific prevalence of crystal facets that create nearly perfect black material at visible wavelengths are proposed. The sharp transition of absorbance near 700 nm wavelength light is attributed to the near‐unity ratio of (−111)/(111) the crystal facets and a crystal size of around 100 Å for the (−111) plane. Although indistinguishable from carbon black and with the same degree of measured blackness (My value 135.5), the nanocrystalline CuO shows 1500% better detectability by LiDAR. The study paves the way for the unconstrained use of dark objects in future society and infrastructure, moving a step closer toward fully autonomous operation of vehicles and robots.