This paper investigates the breaking point between fast- and slow-light in a degenerate two-level atomic system, where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the...This paper investigates the breaking point between fast- and slow-light in a degenerate two-level atomic system, where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the strength of the pumping field. An equivalent incoherent pumping rate is introduced in this simplified theoretical model which exploits the dependence of this feature. The experimental observation is presented as evidence of the breaking point where the injected power is about 0.08 mW.展开更多
In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Ke...In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Kerr medium (non-linear) and the Stark effect. The wave function of the complete system interacting with a coherent and the thermal field is calculated numerically affected by ID, Kerr (non-linear) and Stark effects. It has been seen that the Stark, Kerr, ID and the thermal environment have a significant effect during the time evolution of the quantum system. Quantum Fisher information (QFI) and QE decrease as the value of the ID parameter is increased in the thermal field without the atomic movement. It is seen that QFI and von Neumann entropy (VNE) show an opposite and periodic response in the presence of atomic motion. The non-linear Kerr medium has a more prominent and significant effect on the QE as the value of the Kerr parameter is decreased. At smaller values of the non-linear Kerr parameter, the VNE increases, however, QFI decreases, so QFI and VNE have a monotonic connection with one another. As the value of the Kerr parameter is increased, the effect of non-linear Kerr doesn’t stay critical on both QFI and QE. However, a periodic response of QE is seen because of the atomic movement which becomes modest under natural impacts. Moreover, it has been seen that QFI and QE rot soon at the smaller values of the Stark parameter. However, as the value of the Stark parameter is increased, the QFI and QE show periodic response even when the atomic movement is absent.展开更多
A novel method to control the group velocity of light propagation in a two-level atomic system without additional optical field is proposed. Numerical result and experimental data shows that by changing the magnetic f...A novel method to control the group velocity of light propagation in a two-level atomic system without additional optical field is proposed. Numerical result and experimental data shows that by changing the magnetic field intensity and vapor temperature, the group velocity of probe light can be controlled in an appropriate region.展开更多
Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision,relatively small size among atomic gyroscopes,and promising potential for miniaturiza...Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision,relatively small size among atomic gyroscopes,and promising potential for miniaturization.In particular,the spin-exchange relaxation-free(SERF)atomic gyroscope relies on optical pumping to polarize atoms,enabling rotation sensing through the Faraday optical rotation angle(FORA).However,fluctuations in atomic density introduce systematic errors in FORA measurements,limiting long-term stability.We present a data-driven decoupling method that isolates atomic density fluctuations from the FORA signal by modeling spatially resolved light absorption in the vapor cell.The model accounts for the spatial distribution of spin polarization in the pump-light interaction volume,density-dependent relaxation rates,wall-induced relaxation,and polarization diffusion,and is implemented within a finite-element framework.Compared to the conventional Lambert-Beer law,which assumes one-dimensional homogeneity,our approach captures the full threedimensional density and polarization distribution,significantly improving the accuracy of light absorption modeling.The resulting absorption-density maps are used to train a feedforward neural network,yielding a high-precision estimator for atomic density fluctuations.This estimator enables the construction of a decoupling equation that separates the density contribution from the FORA signal.Experimental validation shows that this method improves the bias instability atσ(100 s)of the gyroscope was improved by 73.1%compared to traditional platinum-resistance-based stabilization.The proposed framework is general and can be extended to other optical pumping-based sensors,such as optically pumped magnetometers.展开更多
Single-atom catalysts(SACs)have demonstrated excellent performance in heterogeneous catalytic reactions owing to their maximized atomic efficiency,distinctive geometric,and electronic configurations.However,the effica...Single-atom catalysts(SACs)have demonstrated excellent performance in heterogeneous catalytic reactions owing to their maximized atomic efficiency,distinctive geometric,and electronic configurations.However,the efficacy of SACs remains limited for certain reactions requiring simultaneous activation of multiple reactants over metallic active sites.Herein,we report an atomically dispersed Pt1Ru1 dual-atom pair site anchored on nanodiamond@graphene(ND@G)for CO oxidation.The Pt1Ru1 dual-atom catalyst shows an exceptional turnover frequency(TOF)of 17.6.10^(-2)s^(-1)at significantly lower temperature(30℃),achieving a tenfold increase in TOF compared to singleatom Pt1/ND@G catalyst(1.5.10^(-2)s^(-1))and surpassing to previously reported Pt-based catalysts under similar conditions.Moreover,the catalyst demonstrates excellent stability,maintaining its activity for 40 h at 80℃without significant deactivation.The superior catalytic performance of Pt-Ru dual-atom catalysts is attributed to the synergistic effect between Pt and Ru atoms with enhanced metallicity for improving simultaneous adsorption and activation of CO and O_(2),and the tuning of conventional competitive reactant adsorption into a non-competitive pathway over dual-atom pair sites.The present work manifests the advantages of dual-atom pair sites in heterogeneous catalysis and paves the way for precise design of catalysts at the atomic scale.展开更多
The development of catalysts with highly efficient oxygen evolution performance and low-Ir loading is key to scaling up the application of proton exchange membrane(PEM)water electrolysis technology.Here,an Ir-skin cat...The development of catalysts with highly efficient oxygen evolution performance and low-Ir loading is key to scaling up the application of proton exchange membrane(PEM)water electrolysis technology.Here,an Ir-skin catalyst(Ir@KM)is realized on a potassium-manganese oxide(K_(0.25)MnO_(x)(KM))using an ion-exchange method.The Ir-skin over the prepared Ir@KM has a low Ir-Ir atomic distance,endowing an energetically favorable oxide path mechanism to allow a low theoretical overpotential of 0.13 V.Ir@KM offers a low overpotential of~280 mV at a current density of 10 mA cm^(-2)and provides a high mass activity of up to 18,500 A at a cell voltage of 1.8 V in PEM,which is 17.6 times higher than that of IrO_(2),demonstrating a significant advantage in reducing the cost of the membrane electrode.The presented Ir-skin concept represents a promising strategy to fabricate low-Ir catalyst with high activity and durability for practical applications of PEM.展开更多
Chlorinated antibiotics pose great challenges in efficient removal,while for the first time,this work greatly enhanced their electrocatalytic dechlorination performance by construction of non-noble metal Co_(3)O_(4)/g...Chlorinated antibiotics pose great challenges in efficient removal,while for the first time,this work greatly enhanced their electrocatalytic dechlorination performance by construction of non-noble metal Co_(3)O_(4)/g-C_(3)N_(4) heterojunctions to improve process cost-effectiveness.The Co_(3)O_(4)/g-C_(3)N_(4) heterojunction demonstrated an effective removal of 93.6%thiamphenicol(TAP)within 45 min,with the rate constant(0.0584 min^(-1))that was 2.4 and 2.8 times that of Co_(3)O_(4) and g-C_(3)N_(4) alone,respectively.The formation of heterojunctions facilitated electron transfer,enriched the electron density on Co_(3)O_(4),and enhanced the adsorption of pollutants as well as the desorption of degradation intermediates.The enhanced production of atomic hydrogen(H*)of Co_(3)O_(4)/g-C_(3)N_(4),which increased by 13.6-28.2 times,contributed more to pollutant removal(64.0%),much higher than that of Co_(3)O_(4)(37.3%)and g-C_(3)N_(4)(6.1%).The energy barrier for H_(2) formation on Co_(3)O_(4)/g-C_(3)N_(4)(0.75 eV)was higher than that on Co_(3)O_(4)(-1.84 eV),supporting that it could stabilize H*and inhibit the formation of H_(2).The Co_(3)O_(4)/g-C_(3)N_(4) heterojunction exhibited stable performance with less impact by pH and co-existing ions,and posed effectiveness for the dechlorination of typical chlorinated antibiotics.This study offers an efficient and sustainable strategy for constructing heterojunctions to enhance the performance of non-noble metal catalysts in electrocatalytic dechlorination.展开更多
We study the optical properties of a two-level atomic ensemble controlled by a high-finesse cavity. Even though the cavity is initially in the vacuum state in the absence of external driving, the probe response of the...We study the optical properties of a two-level atomic ensemble controlled by a high-finesse cavity. Even though the cavity is initially in the vacuum state in the absence of external driving, the probe response of the atomic ensemble can be dramatically modified. When the collectively enhanced atom–cavity coupling is strong enough and the cavity decay rate is much smaller than the atomic damping rate, an electromagnetically induced transparency-like coherent phenomenon emerges with a dip absorption for the response of the two-level atoms in the cavity without driving, and thus is called vacuum induced transparency. We also show the slow light with very low group velocity in such an atomic ensemble.展开更多
From the viewpoint of quantum information, this paper studies preparation and control of atomic optimal entropy squeezing states （AOESS） for a moving two-level atom under control of the two-mode squeezing vacuum fie...From the viewpoint of quantum information, this paper studies preparation and control of atomic optimal entropy squeezing states （AOESS） for a moving two-level atom under control of the two-mode squeezing vacuum fields. Necessary conditions of preparation of the AOESS are analysed, and numerical verification of the AOESS is finished. It shows that the AOESS can be prepared by controlling the time of the atom interaction with the field, cutting the entanglement between the atom and field, and adjusting squeezing factor of the field. An atomic optimal entropy squeezing sudden generation in different components can alternately be realized by controlling the field-mode structure parameter.展开更多
The T_(1)(Al_(2) CuLi)phase is one of the most effective strengthening nanoscale-precipitate in Al-Cu alloys with Li.However,its formation and evolution still need to be further clarified during aging due to the compl...The T_(1)(Al_(2) CuLi)phase is one of the most effective strengthening nanoscale-precipitate in Al-Cu alloys with Li.However,its formation and evolution still need to be further clarified during aging due to the complex precipitation sequences.Here,a detailed investigation has been carried out on the atomic struc-tural evolution of T_(1) precipitate in an aged Al-Cu-Li-Mg-Ag alloy using state-of-the-art Cs-corrected high-angle annular dark field(HAADF)-coupled with integrated differential phase contrast(iDPC)-scanning transmission electron microscopy(STEM)and energy-dispersive X-ray spectroscopy(EDXS)techniques.An intermediate T_(1)’phase between T_(1p) and T_(1) phase,with a crystal structure and orientation rela-tionship consistent with T_(1),but exhibiting different atomic occupancy and chemical composition was found.We observed the atomic structural transformation from T_(1p) to T_(1)’phase(fcc→hcp),involving only 1/12<112>Al shear component.DFT calculation results validated our proposed structural models and the precipitation sequence.Besides,the distributions of minor solute elements(Ag,Mg,and Zn)in the pre-cipitates exhibited significant differences.These findings may contribute to a further understanding of the nucleation mechanism of T_(1) precipitate.展开更多
Metal-based catalysts are prevalent in the CO_(2) hydrogenation to methanol owing to their remarkable catalytic activity.Herein,Ru/In_(2)O_(3) catalysts with different morphologies obtained by doping Ru into In_(2)O_(...Metal-based catalysts are prevalent in the CO_(2) hydrogenation to methanol owing to their remarkable catalytic activity.Herein,Ru/In_(2)O_(3) catalysts with different morphologies obtained by doping Ru into In_(2)O_(3) with irregular,rod-like,and flower-like morphologies are used for catalytic CO_(2) hydrogenation to methanol.Results indicate that the flower-like Ru/In_(2)O_(3)(Ru/In_(2)O_(3)-F)exhibits higher catalytic performance than Ru/In_(2)O_(3) with other morphologies,achieving a 12.9%CO_(2) conversion,74.02%methanol selectivity,and 671.36 mg_(MeOH) h^(−1) g_(cat)^(−1) methanol spatiotemporal yield.Furthermore,Ru/In_(2)O_(3)-F maintains its catalytic stability over 200 h at 5 MPa and 290℃.The promotional effect mainly stems from the fact that electronic structure of Ru can be effectively adjusted by modulating the morphology of In_(2)O_(3).The strong interaction between atomically dispersed Ru and In_(2)O_(3)-F enhances the structural stability of Ru,inhibiting the agglomeration of the catalyst during the reaction process.Furthermore,density-functional theory calculations reveal that highly dispersed Ru atoms not only perform efficient and rapid electronic gain and loss processes,facilitating the catalytic activation of H_(2) into H intermediates.It also enables the generated reactive H to rapidly overflow to the surrounding In sites to participate in CO_(2) reduction.These findings provide a theoretical basis for the development of high-performance catalysts for CO_(2) hydrogenation.展开更多
In this paper, we study the dynamics of the atomic inversion, scaled atomic Wehrl entropy and marginal atomic Wehrl density for a single two-level atom interacting with SU(1,1) quantum system. We obtain the expectatio...In this paper, we study the dynamics of the atomic inversion, scaled atomic Wehrl entropy and marginal atomic Wehrl density for a single two-level atom interacting with SU(1,1) quantum system. We obtain the expectation values of the atomic variables using specific initial conditions. We examine the effects of different parameters on the scaled atomic Wehrl entropy and marginal atomic Wehrl density. We observe an interesting monotonic relation between the different physical quantities for different values of the initial atomic position and detuning parameter.展开更多
Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machin...Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machining.Noxious slurries are widely used in conventional chemical mechanical polishing(CMP),resulting in the possible pollution to the environment.Moreover,the traditional slurries normally contain more than four ingredients,causing difficulties to control the process and quality of CMP.To solve these challenges,a novel green CMP for single crystal diamond was developed,consisting of only hydrogen peroxide,diamond abrasive and Prussian blue(PB)/titania catalyst.After CMP,atomic surface is achieved with surface roughness Sa of 0.079 nm,and the MRR is 1168 nm·h^(-1).Thickness of damaged layer is merely 0.66 nm confirmed by transmission electron microscopy(TEM).X-ray photoelectron spectroscopy,electron paramagnetic resonance and TEM reveal that·OH radicals form under ultraviolet irradiation on PB/titania catalyst.The·OH radicals oxidize diamond,transforming it from monocrystalline to amorphous atomic structure,generating a soft amorphous layer.This contributes the high MRR and formation of atomic surface on diamond.The developed novel green CMP offers new insights to achieve atomic surface of diamond for potential use in their high-performance devices.展开更多
Broadband transparent films play a pivotal role in various applications such as lenses and solar cells,particularly porous structured transparent films exhibit significant potential.This study investigates a porous Si...Broadband transparent films play a pivotal role in various applications such as lenses and solar cells,particularly porous structured transparent films exhibit significant potential.This study investigates a porous SiO_(2) refractive index gradient anti-reflective film prepared by atomic layer deposition(ALD).A porous SiO_(2) film with gradual porosity was obtained by phosphoric acid etching of Al_(2)O_(3)/SiO_(2) multilayers with gradient Al2O3 ratios,achieving a gradual decrease in refractive index from the substrate to the surface.The film exhibited an average transmittance as high as 97.8%within the wavelength range from 320 nm to 1200 nm.The environmental adaptability was further enhanced by surface modification using rare earth oxide(REO)La_(2)O_(3),resulting in formation of a lotus leaf-like structure and achieving a water contact angle of 100.0°.These data proved that the modification significantly improved hydrophobic self-cleaning capability while maintaining exceptional transparency of the film.The surface structure of the modified film remained undamaged even after undergoing wipe testing,demonstrating its excellent surface durability.展开更多
Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Her...Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.展开更多
Single-atom catalysts(SACs),in which isolated metal atoms such as palladium(Pd)are anchored on solid supports,promise breakthroughs in energy conversion and catalysis.However,balancing their activity(reaction speed)an...Single-atom catalysts(SACs),in which isolated metal atoms such as palladium(Pd)are anchored on solid supports,promise breakthroughs in energy conversion and catalysis.However,balancing their activity(reaction speed)and stability(longevity)remains challenging,as the interplay between metal atoms,supports,and reactants is poorly understood.展开更多
Regulating the electronic structure and oxygencontaining intermediates adsorption behavior on Fe-based catalysts is of great significance to cope with the sluggish oxygen reduction reaction(ORR)kinetics,but it still r...Regulating the electronic structure and oxygencontaining intermediates adsorption behavior on Fe-based catalysts is of great significance to cope with the sluggish oxygen reduction reaction(ORR)kinetics,but it still remains a great challenge.In this work,Fe atom clusters(Fe_(AC))modified by high-density Cu single atoms(Cu_(SA))in a N,S-doped porous carbon substrate(Fe_(AC)/Cu_(SA)@NCS)is reported for enhanced ORR electrocatalysis.Fe_(AC)/Cu_(SA)@NCS exhibits excellent ORR performance with a half-wave potential(E_(1/2))of 0.911 V,a high four-electron process selectivity and excellent stability.The ORR performance is also verified in the Fe_(AC)/Cu_(SA)@NCS-based Zn-air battery,which shows a high peak power density of 192.67 mW cm^(-2),a higher specific capacity of 808.3 mAh g^(-1)and impressive charge-discharge cycle stability.Moreover,density functional theory calculations show that Cu single atoms synergistically modulate the electronic structure Fe active atoms in Fe atomic clusters,reducing the energy barrier of the rate-determining step(i.e.,*OH desorption)on Fe_(AC)/Cu_(SA)@NCS.This work provides an effective way to regulate the electronic structure of Fe-based catalysts and optimize their electrocatalytic activity based on the introduction of a second metal source.展开更多
Heteroatom doping is a promising strategy for designing cost-effective and stable electrocatalysts toward the oxygen evolution reaction(OER),but the enhancement mechanism remains unclear.Herein,atomic Ir-O-Cu and Ir-O...Heteroatom doping is a promising strategy for designing cost-effective and stable electrocatalysts toward the oxygen evolution reaction(OER),but the enhancement mechanism remains unclear.Herein,atomic Ir-O-Cu and Ir-O-Ir motifs are engineered into CuO nanowires via cation exchange and dehydration to elucidate the OER mechanism.Systematic characterizations confirm the atomic dispersion of Ir within the CuO lattice and the electron transfer from Ir to CuO while preserving the host structure.The asprepared single-atom Ir-doped CuO(IrSA-CuO),featuring predominant Cu-O-Ir motifs and coexisting IrO-Ir motifs,achieves a low OER overpotential of 204 mV at 10 mA cm^(-2)in 1 M KOH,coupled with a 69-fold higher mass activity than commercial IrO_(2).Furthermore,the Ir_(SA)-CuO maintains long-term stability for 300 h at 200 mA cm^(-2)with minimal overpotential alteration and an additional 120 h at500 mA cm^(-2)with overpotential increased by 15 mV.In situ Raman spectroscopy reveals that the Ir-O-Ir motifs suppress Cu^(Ⅱ) oxidation to Cu^(Ⅲ) by delaying the onset potential,enhancing the structural stability during OER.Density functional theory calculations demonstrate the Cu-O-Ir motifs lower the adsorption energy of bridged ^(*)O via asymmetric bonding,accelerating ^(*)OOH formation in the ratedetermining step.This work presents a heteroatom engineering strategy to balance electrocatalytic activity and durability,providing a blueprint for industrial electrocatalyst design.展开更多
Heat dissipation highly relies on the thermal conductivity(κ)of materials.Materials with large bandgaps and signifcant atomic mass ratios,such as BAs,SiC,andθ-TaN,have attracted considerable attention due to their p...Heat dissipation highly relies on the thermal conductivity(κ)of materials.Materials with large bandgaps and signifcant atomic mass ratios,such as BAs,SiC,andθ-TaN,have attracted considerable attention due to their potential for achieving ultra-highκ,with BAs serving as a particularly representative example due to its unique combination of large bandgap and high thermal conductivity.In this paper,the efects of atomic mass modifcation on phonon bandgap andκare systematically investigated using a BAs model,accounting for both three-and four-phonon scattering processes.A 20%increase inκcan be obtained by substituting B,achieved through widening the phonon bandgap,which suppresses phonon scattering.Notably,the AAOO four-phonon scattering channel is more suppressed than the AAO three-phonon channel,leading to an increased phonon lifetime(τ).For As,κcan also be enhanced by 5%when replaced by lighter atoms,such as^(69)As,primarily due to the increased phonon group velocity(υ).We systematically clarify how atomic-mass-induced bandgap variations afectτ,υ,and thereforeκin wide-bandgap systems.Our work provides a specifc scheme for further improving the ultra-highκof materials with large bandgaps,which possesses great guiding signifcance.展开更多
With the increase in the demand for wearable devices, temperature-sensing capability is an essential function for flexible and transparent applications. Particularly, the long-term stability of a device is highly desi...With the increase in the demand for wearable devices, temperature-sensing capability is an essential function for flexible and transparent applications. Particularly, the long-term stability of a device is highly desirable for use in daily life. In this study, a flexible and transparent self-powered temperature sensor with remarkable air stability was developed by employing a one-atom-thick monolayer graphene encapsulated with an extremely thin metal oxide layer. Graphene thermocouples were constructed by inducing p- and n-type doping on a high-quality monolayer graphene placed on a transparent polymer film. The entire graphene film was treated by a modulated oxygen plasma, which induced p-type doping with minimal defects on graphene. Half of the graphene was coated with polyethylenimine to form n-type graphene. The graphene p–n junction was encapsulated with a 14-nm-thick ultrathin Al_(2)O_(3) using atomic layer deposition (ALD). The graphene thermocouple exhibited a high Seebeck coefficient of 81.6 ± 2.4 µV/K, high linearity with a coefficient of determination of 0.999, rapid response with a time constant of 0.59 s, low thermal hysteresis, and wide operating temperature range. Owing to the ALD-Al_(2)O_(3) layer, the graphene thermocouple exhibited exceptional air stability, maintaining the Seebeck coefficient for 1028 days. Furthermore, the ultimate thinness of the graphene thermocouple rendered it with an extreme optical transmittance of 94.8 % at a wavelength of 550 nm and a small critical bending radius of 5.71 mm.展开更多
基金Project supported by the Key Program of the National Natural Science Foundation of China (Grant No.60837004)the Key Project of Jiangxi Electric Power Company (Grant Nos.200950801 and 200950802)
文摘This paper investigates the breaking point between fast- and slow-light in a degenerate two-level atomic system, where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the strength of the pumping field. An equivalent incoherent pumping rate is introduced in this simplified theoretical model which exploits the dependence of this feature. The experimental observation is presented as evidence of the breaking point where the injected power is about 0.08 mW.
文摘In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Kerr medium (non-linear) and the Stark effect. The wave function of the complete system interacting with a coherent and the thermal field is calculated numerically affected by ID, Kerr (non-linear) and Stark effects. It has been seen that the Stark, Kerr, ID and the thermal environment have a significant effect during the time evolution of the quantum system. Quantum Fisher information (QFI) and QE decrease as the value of the ID parameter is increased in the thermal field without the atomic movement. It is seen that QFI and von Neumann entropy (VNE) show an opposite and periodic response in the presence of atomic motion. The non-linear Kerr medium has a more prominent and significant effect on the QE as the value of the Kerr parameter is decreased. At smaller values of the non-linear Kerr parameter, the VNE increases, however, QFI decreases, so QFI and VNE have a monotonic connection with one another. As the value of the Kerr parameter is increased, the effect of non-linear Kerr doesn’t stay critical on both QFI and QE. However, a periodic response of QE is seen because of the atomic movement which becomes modest under natural impacts. Moreover, it has been seen that QFI and QE rot soon at the smaller values of the Stark parameter. However, as the value of the Stark parameter is increased, the QFI and QE show periodic response even when the atomic movement is absent.
文摘A novel method to control the group velocity of light propagation in a two-level atomic system without additional optical field is proposed. Numerical result and experimental data shows that by changing the magnetic field intensity and vapor temperature, the group velocity of probe light can be controlled in an appropriate region.
基金supported by the Beijing Natural Science Foundation(Grant No.3252013)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0300402)+1 种基金the National Natural Science Foundation of China(Grant No.61673041)Key Area Research and Development Program of Guangdong Province(Grant No.2021B0101410005)。
文摘Atomic spin gyroscopes are promising candidates for next-generation inertial navigation due to extremely high theoretical precision,relatively small size among atomic gyroscopes,and promising potential for miniaturization.In particular,the spin-exchange relaxation-free(SERF)atomic gyroscope relies on optical pumping to polarize atoms,enabling rotation sensing through the Faraday optical rotation angle(FORA).However,fluctuations in atomic density introduce systematic errors in FORA measurements,limiting long-term stability.We present a data-driven decoupling method that isolates atomic density fluctuations from the FORA signal by modeling spatially resolved light absorption in the vapor cell.The model accounts for the spatial distribution of spin polarization in the pump-light interaction volume,density-dependent relaxation rates,wall-induced relaxation,and polarization diffusion,and is implemented within a finite-element framework.Compared to the conventional Lambert-Beer law,which assumes one-dimensional homogeneity,our approach captures the full threedimensional density and polarization distribution,significantly improving the accuracy of light absorption modeling.The resulting absorption-density maps are used to train a feedforward neural network,yielding a high-precision estimator for atomic density fluctuations.This estimator enables the construction of a decoupling equation that separates the density contribution from the FORA signal.Experimental validation shows that this method improves the bias instability atσ(100 s)of the gyroscope was improved by 73.1%compared to traditional platinum-resistance-based stabilization.The proposed framework is general and can be extended to other optical pumping-based sensors,such as optically pumped magnetometers.
基金supported by the National Key R&D Program of China(2021YFA1502802)the National Natural Science Foundation of China(U21B2092,22202213,22402210,22502215,22502214,22572200,and 22579171)+4 种基金the International Partnership Program of Chinese Academy of Sciences(172GJHZ2022028MI)the Shenyang Bureau of Science and Technology(24-213-3-25)the Natural Science Foundation of Liaoning Province(2025BS0153)Zhongke Technology Achievement Transfer and Transformation Center of Henan Province 2025119The XAS experiments were conducted in Beijing Synchrotron Radiation Facility(BSRF)and Shanghai Synchrotron Radiation Facility(SSRF).
文摘Single-atom catalysts(SACs)have demonstrated excellent performance in heterogeneous catalytic reactions owing to their maximized atomic efficiency,distinctive geometric,and electronic configurations.However,the efficacy of SACs remains limited for certain reactions requiring simultaneous activation of multiple reactants over metallic active sites.Herein,we report an atomically dispersed Pt1Ru1 dual-atom pair site anchored on nanodiamond@graphene(ND@G)for CO oxidation.The Pt1Ru1 dual-atom catalyst shows an exceptional turnover frequency(TOF)of 17.6.10^(-2)s^(-1)at significantly lower temperature(30℃),achieving a tenfold increase in TOF compared to singleatom Pt1/ND@G catalyst(1.5.10^(-2)s^(-1))and surpassing to previously reported Pt-based catalysts under similar conditions.Moreover,the catalyst demonstrates excellent stability,maintaining its activity for 40 h at 80℃without significant deactivation.The superior catalytic performance of Pt-Ru dual-atom catalysts is attributed to the synergistic effect between Pt and Ru atoms with enhanced metallicity for improving simultaneous adsorption and activation of CO and O_(2),and the tuning of conventional competitive reactant adsorption into a non-competitive pathway over dual-atom pair sites.The present work manifests the advantages of dual-atom pair sites in heterogeneous catalysis and paves the way for precise design of catalysts at the atomic scale.
基金supported by the Hainan Province Science and Technology Special Fund(ZDYF2023GXJS165)the National Natural Science Foundation of China(52164028,22109035,52274297)+2 种基金the Foundation of State Key Laboratory of Marine Resource Utilization in South China Sea(Hainan University,MRUKF2021029)the Start-up Research Foundation of Hainan University(KYQD(ZR)-20008,20084,21170)the Specific Research Fund of the Innovation Platform for Academicians of Hainan Province。
文摘The development of catalysts with highly efficient oxygen evolution performance and low-Ir loading is key to scaling up the application of proton exchange membrane(PEM)water electrolysis technology.Here,an Ir-skin catalyst(Ir@KM)is realized on a potassium-manganese oxide(K_(0.25)MnO_(x)(KM))using an ion-exchange method.The Ir-skin over the prepared Ir@KM has a low Ir-Ir atomic distance,endowing an energetically favorable oxide path mechanism to allow a low theoretical overpotential of 0.13 V.Ir@KM offers a low overpotential of~280 mV at a current density of 10 mA cm^(-2)and provides a high mass activity of up to 18,500 A at a cell voltage of 1.8 V in PEM,which is 17.6 times higher than that of IrO_(2),demonstrating a significant advantage in reducing the cost of the membrane electrode.The presented Ir-skin concept represents a promising strategy to fabricate low-Ir catalyst with high activity and durability for practical applications of PEM.
基金supported by Natural Science Foundation of China(Nos.U23B20165 and 52170085)National Key R&D Program International Cooperation Project(No.2023YFE0108100)+1 种基金Key Project of Natural Science Foundation of Tianjin(No.21JCZDJC00320)Fundamental Research Funds for the Central Universities,Nankai University.
文摘Chlorinated antibiotics pose great challenges in efficient removal,while for the first time,this work greatly enhanced their electrocatalytic dechlorination performance by construction of non-noble metal Co_(3)O_(4)/g-C_(3)N_(4) heterojunctions to improve process cost-effectiveness.The Co_(3)O_(4)/g-C_(3)N_(4) heterojunction demonstrated an effective removal of 93.6%thiamphenicol(TAP)within 45 min,with the rate constant(0.0584 min^(-1))that was 2.4 and 2.8 times that of Co_(3)O_(4) and g-C_(3)N_(4) alone,respectively.The formation of heterojunctions facilitated electron transfer,enriched the electron density on Co_(3)O_(4),and enhanced the adsorption of pollutants as well as the desorption of degradation intermediates.The enhanced production of atomic hydrogen(H*)of Co_(3)O_(4)/g-C_(3)N_(4),which increased by 13.6-28.2 times,contributed more to pollutant removal(64.0%),much higher than that of Co_(3)O_(4)(37.3%)and g-C_(3)N_(4)(6.1%).The energy barrier for H_(2) formation on Co_(3)O_(4)/g-C_(3)N_(4)(0.75 eV)was higher than that on Co_(3)O_(4)(-1.84 eV),supporting that it could stabilize H*and inhibit the formation of H_(2).The Co_(3)O_(4)/g-C_(3)N_(4) heterojunction exhibited stable performance with less impact by pH and co-existing ions,and posed effectiveness for the dechlorination of typical chlorinated antibiotics.This study offers an efficient and sustainable strategy for constructing heterojunctions to enhance the performance of non-noble metal catalysts in electrocatalytic dechlorination.
基金Project supported by the National Natural Science Foundation of China(Grant No.11304010)
文摘We study the optical properties of a two-level atomic ensemble controlled by a high-finesse cavity. Even though the cavity is initially in the vacuum state in the absence of external driving, the probe response of the atomic ensemble can be dramatically modified. When the collectively enhanced atom–cavity coupling is strong enough and the cavity decay rate is much smaller than the atomic damping rate, an electromagnetically induced transparency-like coherent phenomenon emerges with a dip absorption for the response of the two-level atoms in the cavity without driving, and thus is called vacuum induced transparency. We also show the slow light with very low group velocity in such an atomic ensemble.
基金Project supported by the National Natural Science Foundation of China (Grant No. 19874020)the Natural Science Foundation of Hunan Province of China (Grant Nos. 09JJ3012 and 10JJ9002)the Research Foundation of Education Bureau of Hunan Province of China (Grant No. 10A032)
文摘From the viewpoint of quantum information, this paper studies preparation and control of atomic optimal entropy squeezing states （AOESS） for a moving two-level atom under control of the two-mode squeezing vacuum fields. Necessary conditions of preparation of the AOESS are analysed, and numerical verification of the AOESS is finished. It shows that the AOESS can be prepared by controlling the time of the atom interaction with the field, cutting the entanglement between the atom and field, and adjusting squeezing factor of the field. An atomic optimal entropy squeezing sudden generation in different components can alternately be realized by controlling the field-mode structure parameter.
基金supported by the Pre-research fund(No.412130024).
文摘The T_(1)(Al_(2) CuLi)phase is one of the most effective strengthening nanoscale-precipitate in Al-Cu alloys with Li.However,its formation and evolution still need to be further clarified during aging due to the complex precipitation sequences.Here,a detailed investigation has been carried out on the atomic struc-tural evolution of T_(1) precipitate in an aged Al-Cu-Li-Mg-Ag alloy using state-of-the-art Cs-corrected high-angle annular dark field(HAADF)-coupled with integrated differential phase contrast(iDPC)-scanning transmission electron microscopy(STEM)and energy-dispersive X-ray spectroscopy(EDXS)techniques.An intermediate T_(1)’phase between T_(1p) and T_(1) phase,with a crystal structure and orientation rela-tionship consistent with T_(1),but exhibiting different atomic occupancy and chemical composition was found.We observed the atomic structural transformation from T_(1p) to T_(1)’phase(fcc→hcp),involving only 1/12<112>Al shear component.DFT calculation results validated our proposed structural models and the precipitation sequence.Besides,the distributions of minor solute elements(Ag,Mg,and Zn)in the pre-cipitates exhibited significant differences.These findings may contribute to a further understanding of the nucleation mechanism of T_(1) precipitate.
基金financially supported by the Key Laboratory of Carbon-based Energy Molecular Chemical Utilization Technology in Guizhou Province(No.2023008)Guizhou Provincial Science and Technology Projects(No.ZKZD2023004)+1 种基金One Hundred Person Project of Guizhou Province(No.GCC 2023013)Scientific and Technological Innovation Talents Team Project of Guizhou Province(No.CXTD2023029).
文摘Metal-based catalysts are prevalent in the CO_(2) hydrogenation to methanol owing to their remarkable catalytic activity.Herein,Ru/In_(2)O_(3) catalysts with different morphologies obtained by doping Ru into In_(2)O_(3) with irregular,rod-like,and flower-like morphologies are used for catalytic CO_(2) hydrogenation to methanol.Results indicate that the flower-like Ru/In_(2)O_(3)(Ru/In_(2)O_(3)-F)exhibits higher catalytic performance than Ru/In_(2)O_(3) with other morphologies,achieving a 12.9%CO_(2) conversion,74.02%methanol selectivity,and 671.36 mg_(MeOH) h^(−1) g_(cat)^(−1) methanol spatiotemporal yield.Furthermore,Ru/In_(2)O_(3)-F maintains its catalytic stability over 200 h at 5 MPa and 290℃.The promotional effect mainly stems from the fact that electronic structure of Ru can be effectively adjusted by modulating the morphology of In_(2)O_(3).The strong interaction between atomically dispersed Ru and In_(2)O_(3)-F enhances the structural stability of Ru,inhibiting the agglomeration of the catalyst during the reaction process.Furthermore,density-functional theory calculations reveal that highly dispersed Ru atoms not only perform efficient and rapid electronic gain and loss processes,facilitating the catalytic activation of H_(2) into H intermediates.It also enables the generated reactive H to rapidly overflow to the surrounding In sites to participate in CO_(2) reduction.These findings provide a theoretical basis for the development of high-performance catalysts for CO_(2) hydrogenation.
文摘In this paper, we study the dynamics of the atomic inversion, scaled atomic Wehrl entropy and marginal atomic Wehrl density for a single two-level atom interacting with SU(1,1) quantum system. We obtain the expectation values of the atomic variables using specific initial conditions. We examine the effects of different parameters on the scaled atomic Wehrl entropy and marginal atomic Wehrl density. We observe an interesting monotonic relation between the different physical quantities for different values of the initial atomic position and detuning parameter.
基金financial support from the National Key Research and Development Program of China(2018YFA0703400)the Fundamental Research Funds for the Provincial Universities of Zhejiang(GK239909299001021)+1 种基金the Ninth China Association for Science and Technology Youth Talent Lift Project Support Plan(KYZ015324002)the Changjiang Scholars Program of Chinese Ministry of Education。
文摘Atomic surfaces are strictly required by high-performance devices of diamond.Nevertheless,diamond is the hardest material in nature,leading to the low material removal rate(MRR)and high surface roughness during machining.Noxious slurries are widely used in conventional chemical mechanical polishing(CMP),resulting in the possible pollution to the environment.Moreover,the traditional slurries normally contain more than four ingredients,causing difficulties to control the process and quality of CMP.To solve these challenges,a novel green CMP for single crystal diamond was developed,consisting of only hydrogen peroxide,diamond abrasive and Prussian blue(PB)/titania catalyst.After CMP,atomic surface is achieved with surface roughness Sa of 0.079 nm,and the MRR is 1168 nm·h^(-1).Thickness of damaged layer is merely 0.66 nm confirmed by transmission electron microscopy(TEM).X-ray photoelectron spectroscopy,electron paramagnetic resonance and TEM reveal that·OH radicals form under ultraviolet irradiation on PB/titania catalyst.The·OH radicals oxidize diamond,transforming it from monocrystalline to amorphous atomic structure,generating a soft amorphous layer.This contributes the high MRR and formation of atomic surface on diamond.The developed novel green CMP offers new insights to achieve atomic surface of diamond for potential use in their high-performance devices.
文摘Broadband transparent films play a pivotal role in various applications such as lenses and solar cells,particularly porous structured transparent films exhibit significant potential.This study investigates a porous SiO_(2) refractive index gradient anti-reflective film prepared by atomic layer deposition(ALD).A porous SiO_(2) film with gradual porosity was obtained by phosphoric acid etching of Al_(2)O_(3)/SiO_(2) multilayers with gradient Al2O3 ratios,achieving a gradual decrease in refractive index from the substrate to the surface.The film exhibited an average transmittance as high as 97.8%within the wavelength range from 320 nm to 1200 nm.The environmental adaptability was further enhanced by surface modification using rare earth oxide(REO)La_(2)O_(3),resulting in formation of a lotus leaf-like structure and achieving a water contact angle of 100.0°.These data proved that the modification significantly improved hydrophobic self-cleaning capability while maintaining exceptional transparency of the film.The surface structure of the modified film remained undamaged even after undergoing wipe testing,demonstrating its excellent surface durability.
基金supported by National Natural Science Foundation of China(No.523B2070,No.52225606).
文摘Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.
文摘Single-atom catalysts(SACs),in which isolated metal atoms such as palladium(Pd)are anchored on solid supports,promise breakthroughs in energy conversion and catalysis.However,balancing their activity(reaction speed)and stability(longevity)remains challenging,as the interplay between metal atoms,supports,and reactants is poorly understood.
基金financially supported by the National Natural Science Foundation of China(No.22278042)the National Natural Science Foundation of Jiangsu Province(No.BK20240567)+2 种基金the Introduction and Cultivation of Leading Innovative Talents Foundation of Changzhou,Jiangsu Province(No.CQ20220093)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.24KJD530001)the Open Project Program of Key Laboratory of Optic-electric Sensing and Analytical Chemistry for Life Science(No.M2024-7),MOE
文摘Regulating the electronic structure and oxygencontaining intermediates adsorption behavior on Fe-based catalysts is of great significance to cope with the sluggish oxygen reduction reaction(ORR)kinetics,but it still remains a great challenge.In this work,Fe atom clusters(Fe_(AC))modified by high-density Cu single atoms(Cu_(SA))in a N,S-doped porous carbon substrate(Fe_(AC)/Cu_(SA)@NCS)is reported for enhanced ORR electrocatalysis.Fe_(AC)/Cu_(SA)@NCS exhibits excellent ORR performance with a half-wave potential(E_(1/2))of 0.911 V,a high four-electron process selectivity and excellent stability.The ORR performance is also verified in the Fe_(AC)/Cu_(SA)@NCS-based Zn-air battery,which shows a high peak power density of 192.67 mW cm^(-2),a higher specific capacity of 808.3 mAh g^(-1)and impressive charge-discharge cycle stability.Moreover,density functional theory calculations show that Cu single atoms synergistically modulate the electronic structure Fe active atoms in Fe atomic clusters,reducing the energy barrier of the rate-determining step(i.e.,*OH desorption)on Fe_(AC)/Cu_(SA)@NCS.This work provides an effective way to regulate the electronic structure of Fe-based catalysts and optimize their electrocatalytic activity based on the introduction of a second metal source.
基金supported by the Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China(No.2021ZR124)。
文摘Heteroatom doping is a promising strategy for designing cost-effective and stable electrocatalysts toward the oxygen evolution reaction(OER),but the enhancement mechanism remains unclear.Herein,atomic Ir-O-Cu and Ir-O-Ir motifs are engineered into CuO nanowires via cation exchange and dehydration to elucidate the OER mechanism.Systematic characterizations confirm the atomic dispersion of Ir within the CuO lattice and the electron transfer from Ir to CuO while preserving the host structure.The asprepared single-atom Ir-doped CuO(IrSA-CuO),featuring predominant Cu-O-Ir motifs and coexisting IrO-Ir motifs,achieves a low OER overpotential of 204 mV at 10 mA cm^(-2)in 1 M KOH,coupled with a 69-fold higher mass activity than commercial IrO_(2).Furthermore,the Ir_(SA)-CuO maintains long-term stability for 300 h at 200 mA cm^(-2)with minimal overpotential alteration and an additional 120 h at500 mA cm^(-2)with overpotential increased by 15 mV.In situ Raman spectroscopy reveals that the Ir-O-Ir motifs suppress Cu^(Ⅱ) oxidation to Cu^(Ⅲ) by delaying the onset potential,enhancing the structural stability during OER.Density functional theory calculations demonstrate the Cu-O-Ir motifs lower the adsorption energy of bridged ^(*)O via asymmetric bonding,accelerating ^(*)OOH formation in the ratedetermining step.This work presents a heteroatom engineering strategy to balance electrocatalytic activity and durability,providing a blueprint for industrial electrocatalyst design.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFA1407001)the Department of Science and Technology of Jiangsu Province(Grant No.BK20220032)+1 种基金support from the Guang Dong Basic and Applied Basic Research Foundation(Grant No.2023A1515010365)support from the Postgraduate Research and Practice Innovation Program of Jiangsu Province under Grant No.KYCX25_1934。
文摘Heat dissipation highly relies on the thermal conductivity(κ)of materials.Materials with large bandgaps and signifcant atomic mass ratios,such as BAs,SiC,andθ-TaN,have attracted considerable attention due to their potential for achieving ultra-highκ,with BAs serving as a particularly representative example due to its unique combination of large bandgap and high thermal conductivity.In this paper,the efects of atomic mass modifcation on phonon bandgap andκare systematically investigated using a BAs model,accounting for both three-and four-phonon scattering processes.A 20%increase inκcan be obtained by substituting B,achieved through widening the phonon bandgap,which suppresses phonon scattering.Notably,the AAOO four-phonon scattering channel is more suppressed than the AAO three-phonon channel,leading to an increased phonon lifetime(τ).For As,κcan also be enhanced by 5%when replaced by lighter atoms,such as^(69)As,primarily due to the increased phonon group velocity(υ).We systematically clarify how atomic-mass-induced bandgap variations afectτ,υ,and thereforeκin wide-bandgap systems.Our work provides a specifc scheme for further improving the ultra-highκof materials with large bandgaps,which possesses great guiding signifcance.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Ministry of Science and ICT(Nos.2022R1A2B5B02002413 and 2022R1A4A1031182)supported by the Next-Generation Intelligence Semiconductor R&D Program through the Korea Planning&Evaluation Institute of Industrial Technology(KEIT)funded by the Ministry of Trade,Industry,and Energy(MOTIE)of Korea(No.20023574).
文摘With the increase in the demand for wearable devices, temperature-sensing capability is an essential function for flexible and transparent applications. Particularly, the long-term stability of a device is highly desirable for use in daily life. In this study, a flexible and transparent self-powered temperature sensor with remarkable air stability was developed by employing a one-atom-thick monolayer graphene encapsulated with an extremely thin metal oxide layer. Graphene thermocouples were constructed by inducing p- and n-type doping on a high-quality monolayer graphene placed on a transparent polymer film. The entire graphene film was treated by a modulated oxygen plasma, which induced p-type doping with minimal defects on graphene. Half of the graphene was coated with polyethylenimine to form n-type graphene. The graphene p–n junction was encapsulated with a 14-nm-thick ultrathin Al_(2)O_(3) using atomic layer deposition (ALD). The graphene thermocouple exhibited a high Seebeck coefficient of 81.6 ± 2.4 µV/K, high linearity with a coefficient of determination of 0.999, rapid response with a time constant of 0.59 s, low thermal hysteresis, and wide operating temperature range. Owing to the ALD-Al_(2)O_(3) layer, the graphene thermocouple exhibited exceptional air stability, maintaining the Seebeck coefficient for 1028 days. Furthermore, the ultimate thinness of the graphene thermocouple rendered it with an extreme optical transmittance of 94.8 % at a wavelength of 550 nm and a small critical bending radius of 5.71 mm.
