Average Figure Of Merit Research Articles

Simple formulation of no-cloning and no-hiding that admits efficient and robust verification

Incompatibility is a feature of quantum theory that sets it apart from classical theory, and the inability to clone an unknown quantum state is one of the most fundamental instances. The no-hiding theorem is another such instance that arises in the context of the black-hole information paradox, and can be viewed as being dual to no-cloning. Here, we formulate both of these fundamental features of quantum theory in a single form that is amenable to efficient verification, and that is robust to errors arising in state preparation and measurements. We extend the notion of unitarity—an average figure of merit that for quantum theory captures the coherence of a quantum channel—to general physical theories. Then, we introduce the notion of compatible unitarity pair (CUP) sets, that correspond to the allowed values of unitarities for compatible channels in the theory. We show that a CUP set constitutes a simple “fingerprint” of a physical theory, and that incompatibility can be studied through them. We derive information-disturbance constraints on quantum CUP sets that encode both the no-cloning/broadcasting and no-hiding theorems of quantum theory. We then develop randomized benchmarking protocols that efficiently estimate quantum CUP sets and provide simulations using IBMQ of the simplest instance. Finally, we discuss ways in which CUP sets and quantum no-go theorems could provide additional information to benchmark quantum devices. Published by the American Physical Society 2024

Dual-core-enhanced surface plasmon resonance for sensing high refractive index liquid based on photonic crystal fiber

A dual-core photonic crystal fiber sensor based on surface plasmon resonance is theoretically proposed for the high-sensitive detection of high refractive index liquid analytes. Dual-core construction can effectively enhance the coupling effect between the fiber-core mode and the surface plasmon polariton modes, leading to sharp loss peaks at the resonance wavelengths. As the refractive index of the targeted analyte varies, the resonance condition will change as well and cause a certain shift of loss peak. Numeric results show that this dual-core fiber sensor exhibits an average linear sensitivity 9538 nm/RIU and a maximum sensitivity is 11400 nm/RIU with a resolution 8.77 × 10−6 RIU. The detected range is broad and covers the high refractive index range from 1.45 to 1.58 with an average figure of merit 284.5 RIU−1. The dependence of structure parameters and the thickness of coated-metal thin-film on sensing performance is performed systemically and suggests different responses. The proposed sensor is highly promising in detecting high refractive index liquid analytes in the fields of biological detection, environmental monitoring and chemical analysis.

High-performance tellurium-free thermoelectric module for moderate temperatures using α-MgAgSb/Mg2(Si,Sn)

α-MgAgSb is a promising thermoelectric material with an average figure of merit above unity between room temperature and 573 K, making it attractive for low temperature waste heat recovery or temperature regulation applications. We demonstrate here the first α-MgAgSb/Mg2(Si,Sn)-based thermoelectric module, where Mg2(Si,Sn) was chosen as n-type counterpart due to its excellent thermoelectric properties, low weight, abundant, and eco-friendly constituents. By using this new material combination, a maximum conversion efficiency of 6.4% and maximum power of 0.68 W were achieved for a temperature difference of 275 K, superior to commercially available (Bi,Te,Sb)-based thermoelectric modules. The Constant Property Model was used to check the validity of the measurement results and to identify room for further improvement. The characterization of the prototype shows a relatively good match between measurement and calculation for most of the thermoelectric module performance parameters; however, the measured internal electrical resistance is around 10% higher than the predicted values, indicating opportunities for further enhancement.

Density-extrapolation Global Variance Reduction (DeGVR) method for large-scale radiation field calculation

The lack of a universal and effective Global Variance Reduction (GVR) method for the deep-penetration Monte Carlo calculation makes it difficult or impossible to calculate the radiation field of large nuclear facilities. We propose a Density-extrapolation Global Variance Reduction (DeGVR) method for the large-scale radiation field calculation. After reducing the density of all materials to avoid the deep penetration problem, two global flux distributions of the two different material densities are obtained with two fixed-source calculations, and then the global flux distribution of the original material density is obtained by extrapolating the two global flux distributions. The global flux distribution of the original material density is then used for global variance reduction. In a large-scale model with a flux attenuation of 1080, the DeGVR method only takes 40.3 minutes to build the radiation field, improves the Average Figure-of-Merit (AV.FOM) up to 85652 times and the counting rate per time (CRPT) up to 88107 times compared with the standard Monte Carlo method. In addition to the high efficiency, the DeGVR method has high universality and robustness because it constructs the global information in a clever way that does not rely on the complex mathematical derivation and geometric modeling. The DeGVR method shows excellent application potential in large-scale radiation analysis.

Defect-Engineering-Stabilized AgSbTe2 with High Thermoelectric Performance.

Thermoelectric (TE) generators enable the direct and reversible conversion between heat and electricity, providing applications in both refrigeration and power generation. In the last decade, several TE materials with relatively high figures of merit (zT) have been reported in the low- and high-temperature regimes. However, there is an urgent demand for high-performance TE materials working in the mid-temperature range (400-700 K). Herein, p-type AgSbTe2 materials stabilized with S and Se co-doping are demonstrated to exhibit an outstanding maximum figure of merit (zTmax ) of 2.3 at 673 K and an average figure of merit (zTave ) of 1.59 over the wide temperature range of 300-673 K. This exceptional performance arises from an enhanced carrier density resulting from a higher concentration of silver vacancies, a vastly improved Seebeck coefficient enabled by the flattening of the valence band maximumand the inhibited formation of n-type Ag2 Te, and ahighly improved stability beyond 673 K. The optimized material is used to fabricate a single-leg device with efficiencies up to 13.3% and a unicouple TE device reaching energy conversion efficiencies up to 12.3% at a temperature difference of 370 K. These results highlight an effective strategy to engineer high-performance TE material in the mid-temperature range.

Near-Perfect TMOKE in Photonic Crystal Structures for Sensing Devices With High Figure of Merit

Near-perfect transverse magneto-optical Kerr effect (TMOKE), which is realized by sandwiching a magnetic-optical film between a photonic crystal (PhC) structure and a metallic mirror, is studied. Near-unity amplitude in TMOKE is observed owing to the excitation of Tamm plasmon polaritons (TPPs) at the interface between the PhC and the metallic mirror. The physical origin behind such giant enhancement of TMOKE is disclosed by studying the magnetic field distributions at resonance and also confirmed by the reflection spectra of the top PhC and the bottom continuous metallic film. Besides, the suitability and the sensitivity of the proposed structure for sensing both gas and aqueous mediums are also illustrated in the last. And it is found that the excellent performance with the averaged figure of merit (FoM) on the order of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.8\times10^{3}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.7\times10^{3}$ </tex-math></inline-formula> can be achieved for sensing gas and aqueous mediums, respectively. We hoped that this work will prompt the development of data magnetic storage, optical filters, waveguide isolators, and novel sensors with improved sensitivity.

Cu2Te Incorporation-Induced High Average Thermoelectric Performance in p-Type Bi2Te3 Alloys.

p-Type (Bi, Sb)2Te3 alloys are attractive materials for near-room-temperature thermoelectric applications due to their high atomic masses and large spin-orbit interactions. However, their narrow band gaps originating from spin-orbit interactions lead to bipolar excitation, thereby limiting average thermoelectrics within a local temperature region (300-400 K). Here, we introduce Cu2Te into the Bi0.3Sb1.7Te3 (BST) lattice to implement high thermoelectrics over a wide temperature range. The carrier concentration is synergistically modulated via Cu substitution and the evolution of intrinsic point defects (antisites and vacancies). Furthermore, the chain effect caused by Cu2Te incorporation in BST is reflected in the improvement of the weighted mobility μW, thereby enhancing the power factor in the whole temperature range. Extrinsic and intrinsic defects due to the incorporation of Cu2Te lead to a significant reduction in the lattice thermal conductivity κL, which is further demonstrated by Raman spectroscopy. Combining κL and μW, the quantity factor B increases from 0.5 to 1 with increasing Cu2Te content due to not only the reduction of κL but also a significant improvement in electrical properties. Eventually, a peak figure of merit (zT) of ∼1.15 at 423 K is achieved in BST-Cu2Te samples, and an average figure of merit (zTave) of ∼1.12 (350-500 K) surpasses other excellent p-type Bi2Te3-based thermoelectrics. Such a synergistic effect can facilitate near-room-temperature thermoelectric applications of Bi2Te3-based alloys and provide chances for the technology space in thermoelectrics.

Realizing ultrahigh average figure of merit through manipulating layered phonon-electron decoupling

Realizing ultrahigh average figure of merit through manipulating layered phonon-electron decoupling

Highly sensitive surface plasmon resonance sensor using perforated optical fiber for biomedical applications

In this paper, a novel mechanism for design of optical fiber refractive index sensors based on surface plasmon resonance (SPR) is suggested. In the proposed method, the internal part of the fiber core is removed to guide the incident light closer to the clad-core interface. Thereafter, the clad is removed and a thin film of gold is coated on the outer part of the core. In the proposed structure, the light beam is guided between the inner and outer parts of the core, where surface plasmons (SPs) are excited. As a result, the absorption reaches to a maximum at SPR wavelengths. The proposed structure is numerically analyzed using finite difference time domain (FDTD) method. The absorption values at the transmitted power spectra correspond to the dielectric constants of the analyte which surrounds the metal. The refractive indices of bio-materials in the range of 1.3 and 1.41 can be measured by the proposed sensor. According to the simulation results, the proposed biosensor has a maximum sensitivity of about 10570 nm/RIU and its average figure of merit is equal to 97.88. The simulation results confirm that the presented structure can be used for bio-sensing applications.

A Sensor Based on One-Dimensional Cylindrical Photonic Crystals and Graphene Elements With a Higher Quality Factor and a Wider Measurement Range

In this paper, a new structure for the sensing and detection of refractive index (RI) based on the one-dimensional cylindrical photonic crystals containing the graphene elements with a higher quality factor (QF) and a wider measurement range are theoretically investigated by the transfer matrix method. The sensing function of the presented structure is that, under impedance matching conditions, the defect cavity captures the tunnel optical Tamm state, and then generates high absorption through electromagnetic resonance. The obtained results show that it is almost unaffected for the sensor in measuring by minor chemical potential, core radius, loss tangent value, and smaller manufacturing roughness. Consequently, it is very tolerant of the working environment and the production industry. However, it is angle-sensitive. As the incident angle ( θ) increases, the sensitivity (S) is enlarged obviously, but the linear area of the sensor shrinks by a large margin. So, the choice of θ should be considered comprehensively. The proposed sensor provides relatively higher performance, ranging from 1.0 ~ 2.8, the S is equivalent to 117.639 nm/RIU, and the average figure of merit is 2707.804. In addition, the average QF arrives at 29906.059. The average detection limit (DL) is 0.0001688 nm, and the lowest DL reaches 0.000006715 nm. In overall sensors, owing to the much-needed to identify substances in the fields of biology, chemistry, environmental monitoring, food safety biological analysis, engineering, and military, the RI sensors are demanded desperately, and it is so far more than other sensor types to research.

Simulation Research on Blood Detection Sensing with Parity-Time Symmetry Structure

To realize the design of a medical sensor with excellent comprehensive performance indexes, herein, a plasma concentration sensing model satisfying the Parity-Time (PT) symmetric condition is proposed. In this paper, the transfer matrix method was used to simulate the transmittance spectrum of the structure, according to the amplification effect on defect mode transmission and various detection performance indexes of the structure. We numerically optimized the parameters of the structure, such as the number of PT-symmetry unit cell N, the sample layer thickness dD as well as the macroscopic Lorentz oscillation intensity α in the PT-symmetry unit cell. The calculation results demonstrate that when the sample concentration changes from 0 g/L to 50 g/L, the wavelength of defect peak shifts from 1538 nm to 1561 nm, and the average quality factor, sensitivity, average figure of merit, average detection limit and average resolution of the structure can reach 78,564, 0.4409 nm/(g/L) (or 227.05 nm/RIU), 11,515 RIU−1, 5.1 × 10−6 RIU and 0.038 g/L, respectively. Not only the sensitivity and resolution of the PT-symmetry structure are better than that of the similar sensors, but it also has excellent comprehensive detection performance, which indicates that the developed sensor can be used in high-precision biomedical detection devices.

Surface plasmon resonance biosensor using inverted graded index optical fiber

A new type of surface plasmon resonance biosensor based on inverted graded index optical fiber is presented. To allow the exciting of the surface plasmons, the cladding is removed and a thin film of gold is coated on the inverted graded index core at this region. This sensor can measure the refractive index (RI) of biomaterials in the range of 1.36–1.48. The simulation results show that the proposed biosensor has a maximum sensitivity of about 7000 nm/RI unit (RIU) and the average figure of merit is 48 RIU−1. The simplicity of the design and its high sensitivity make it a good candidate for low-cost RI sensors suitable for biomaterials.

A Theoretical Proposal for a Refractive Index and Angle Sensor Based on One-Dimensional Photonic Crystals

In this article, a structure based on one-dimensional photonic crystals that can be used for both angle sensing and refractive index sensing is proposed, which is achieved by optical Tamm state. Under Bragg scattering, its features are investigated by the transfer matrix method. This sensing structure is based on a multi-frequency absorption structure, which can achieve an absorption rate higher than 0.9 for three to four frequency points at the same time. The studied results demonstrate that the absorption peaks of such an absorption structure can be changed from three to four by adjusting the number of periods and silver layer thickness. Absorption peaks can occur red and blue shifts employing tailoring the thickness of defect and the angle of the incident light. By altering the thickness of the defect and the number of periods, the interval between the absorption peaks can be dominated. They are all with high-quality factors and can be used to bring about a high absorption sensor for the refractive index or angle. When it acts as a refractive index sensor, the operating range can cover from 2 to 2.7, whose sensitivity and average figure of merit are 32.3 THz/RIU and 100. If the presented device is used as an angle sensor, those values will become 0.5 THz/degree and 1.2, and its measuring range is from 25° to 70°. It can be said that the emergence of this special sensing structure will be possible to have a broad application prospect in the field of measurement.

A long wavelength infrared narrow-band reflection filter based on an asymmetric hexagonal structure

An asymmetric hexagon structure is designed on the micrometer scale to fabricate a narrow-band reflection filter in the long wavelength infrared band. By rotating the hexagon structure 20 degrees, a single narrow-band resonance can be achieved at 7.99μm with high reflectivity of 92% and Q value of 200 simultaneously. The spectral resolution is 40 nm, and the average reflectivity exceeds 90%. By changing the size of the unit cell through a scaling factor k, it can filter across 8-12μm (25 THz–37.5 THz). The dephasing time of the proposed filter is 1.7 ps. We also studied the filtering properties of the proposed filter with significant figure of merit and insertion losses. The average figure of merit can reach 300, and the insignificant insertion loss is only 0.4 dB. The subwavelength filter structure consists of a periodic array of dielectric substrates made of BaF2 and hexagon structure made of Ge with low intrinsic loss, which requires very few layers compared to traditional filters with multilayer films. In addition, the proposed structure is independent to the angles of the incident light. Moreover, it possesses a good tolerance of rounding issue in micro-fabrication process. The position of the center wavelength of the spectra has hardly shift when the sharp vertices become round. The structure can be applied in biosensor and hyperspectral imaging systems.

Improved Average Figure‐of‐Merit of High‐Efficiency Nonfullerene Solar Cells via Minor Combinatory Side Chain Approach

The cost‐effectiveness of polymer solar cells is a very important concern for future applications. In this work, a new combinatory side chain integrating siloxane terminal and alkoxy group is developed, and three polymers, PQSi05, PQSi10, and PQSi25, with 5%, 10%, and 25% contents of the siloxane‐terminated alkoxy side chain, respectively, are successfully synthesized. As the content of the combinatory side chain increases, the surface energy of the corresponding polymer film decreases, showing tunable miscibility in blend films with nonfullerene acceptor IT‐4F. A maximum power conversion efficiency (PCE) of 13.56% is achieved in the PQSi05:IT‐4F‐based device. The minor (5%) combinatory side chain approach retains a low synthetic complexity (SC) of 16.58% for PQSi05. Due to the improved device performance, a low figure‐of‐merit (FOM) of 1.22 is obtained for the PQSi05:IT‐4F blend. Furthermore, the contribution of the IT‐4F acceptor is considered for a comprehensive analysis, yielding an average SC (ASC) of 39.31% and an average FOM (AFOM) of 2.90. After statistical analyses and calculations, the PQSi05:IT‐4F is the best cost‐effective active layer to date. It is revealed that the introduction of the minor combinatory side chain is a promising strategy to develop high‐performing and cost‐effective polymer donors.

Flexible ITO-free sky-blue polymer light-emitting diodes and printed polymer solar cells based on AgNW/PI transparent conductive electrode

In this work, transparent and conductive as well as flexible silver nanowire/polyimide (AgNW/PI) composite film with an average figure of merit as high as 111.3, which is the ratio of electronic conductivity to optical conductivity, is produced by a simple peel-off method without any post treatments. When employing the AgNW/PI composite film as the flexible transparent conductive anode in blue polymer light-emitting diodes, the device shows a high external quantum efficiency of 3.42% which is comparable to the rigid indium tin oxide (ITO)-based control device with an efficiency of 3.96%. Moreover, for the flexible printed polymer solar cell (PSCs) with AgNW/PI as the transparent conductive anode, a high power conversion efficiency of 4.01% is achieved, which is also comparable to that of the rigid ITO-based PSC. This work systematically demonstrates that AgNW/PI composite film has a promising prospect for application in all kinds of flexible optoelectronic devices.

Investigation of Clinical Utility of Radiological Technologist’s Reading Report as a Second Opinion for Medical Doctor Reading of Digital Mammogram

We investigated the clinical utility of a radiological technologist's (RT)'s reports (RRs) as a second opinion by the free-response receiver operating characteristic (FROC) observer study that compared the performance of medical doctors' (MDs') reading of digital mammogram with and without consulting the RR. One hundred women (39 malignant, 61 benign or normal) who underwent diagnostic mammography were selected from among 1674 routine clinical images classified by the degree of difficulty and categories for inclusion in the FROC study. The first FROC study performed by three RTs (RT 1-3) was conducted to collect the data for RR utilized in the second FROC study. The second FROC study was performed by five MDs, and the statistical significance of MDs' performances with and without reference to the RR was investigated by figure of merit (FOM). The FOM values of three RTs obtained in the first FROC study were 0.529, 0.576, and 0.539, respectively. In the second FROC study, RT 2 had the highest FOM, RT 1 the lowest false positives/case, and RT 3 the highest sensitivity. The average FOM values in the second FROC study for the five MDs with/without reference to the RR were as follows: RT 2's RR was 0.534/0.588 (p=0.003), RT 1's RR was 0.500/0.545 (p=0.099), and RT 3's RR was 0.569/0.592 (p=0.324). We concluded that the MDs' performance of reading mammogram was statistically improved by consulting the RR when the RT's reading skill was high.

Probing the path for achieving a broad temperature plateau of the figure of merit in thermoelectric nanocomposite materials

The efficiency of a thermoelectric device depends directly on the average figure of merit (zT) of the material. A high average zT requires a broad temperature plateau with a high zT, but state-of-the-art thermoelectric materials display a peaked zT over a narrow temperature range due to a strong temperature dependence of transport properties. In this work, using Boltzmann transport theory, we systematically investigate the underlying physics and propose a strategy for attaining a broad temperature plateau of zT through proper engineering of the interfacial barrier height in PbTe nanocomposite material. The optimized barrier height (UconstantzT) not only enhances the zT but also maintains its high value over a wide temperature range [Tmin:Tmax]. It has been found that for p = 2.8 × 1020 cm−3, the UconstantzT is 0.112 eV at which zT varies between 1.9–2.14 over a wide temperature range of 550–850 K, resulting in a high average zT of 2.02 in comparison to a bulk value of 1.22. Also, for p = 5 × 1019 cm−3, UconstantzT is 0.102 eV at which zT varies between 1.046–1.435 for a temperature range of 300–600K, resulting in a high average zT of 1.27 over a bulk value of 0.844. The above results show that the range [Tmin:Tmax] depends on carrier concentration which, in turn, determines the position of the Fermi level (Ef) and Fermi window at Tmin and Tmax. To obtain a broad temperature plateau of zT, the findings show that at Tmin, Ef should lie inside the band and zT should show strong variation with barrier height, whereas at Tmax, Ef should lie in the band gap and zT should have little variation with barrier height. This trend allows us to choose UconstantzT which synergistically optimizes the transport properties at Tmin with Tmax to give a broad temperature plateau of zT. This work proposes a new advantage of interfacial scattering which enhances the average zT and also provides necessary guidelines to experimentalists for synthesizing a highly efficient thermoelectric device.

Improved adaptive variance reduction algorithm based on RMC code for deep penetration problems

An adaptive variance reduction algorithm based on RMC code was developed for deep penetration problems. The adaptive variance reduction algorithm uses the conservation of penetration rate and a predictor–corrector algorithm to quickly determine exponential importance parameters or equal-gradient importance parameters with fast iterative convergence. The adaptive variance reduction algorithm greatly accelerates one-dimensional deep penetration problems. However, the previous algorithm does not have capacity of energy bias nor does it support calculations on three-dimensional models. The adaptive variance reduction algorithm is improved to allow for energy bias and for three-dimensional models. The improved algorithm was applied to the HBR2 benchmark with the average Figure of Merit (FOM) of RMC code improved 243 fold. Therefore, this improved adaptive variance reduction algorithm can efficiently deal with complex engineering shielding problems.

Patch-based cellular automata model of urban growth simulation: Integrating feedback between quantitative composition and spatial configuration

Urban land use change modeling can enhance our understanding of processes and patterns of urban growth that emerge from human-environment interactions. Cellular automata (CA) is a common approach for urban land use change modeling that allows for discovering and analyzing potential urban growth pathways through scenario building. Fundamental components of CA such as neighborhood configuration, transition rules, and representation of geographic entities have been examined in depth in the literature. However, trade-offs in the quantitative composition that urban gains from different non-urban land types and their dynamic feedback with the spatial configuration of urban growth are often ignored. The urban CA model proposed in this study links the quantitative composition with the spatial configuration of urban growth by incorporating a trade-off mechanism that adaptively adjusts the combined suitability of occurrence for non-urban land types based on analysis of transition intensity. Besides, a patch growing module based on seeding and scanning mechanisms is used to simulate the occurrence and spreading of spontaneous urban growth, and a time Monte Carlo (TMC) simulation method is employed to represent uncertainties in the decision-making process of urban development. Application of the model in an ecologically representative city, Ezhou, China, reveals improvement on model performance when feedback between the quantitative composition and spatial configuration of urban growth is incorporated. The averaged figure of merit and K-fuzzy indices are 0.5354 and 0.1954 with respect to cell-level agreement and pattern similarity, indicating the utility and reliability of the proposed model for the simulation of realistic urban growth.