This paper proposes a scheme for realization of a three-qubit Toffoli gate operation using three four-level atoms by a selective atom-field interaction in a cavity quantum electrodynamics system. In the proposed proto...This paper proposes a scheme for realization of a three-qubit Toffoli gate operation using three four-level atoms by a selective atom-field interaction in a cavity quantum electrodynamics system. In the proposed protocol, the quantum information is encoded on the stable ground states of atoms, and atomic spontaneous emission is negligible as the large atom-avity detuning effectively suppresses the spontaneous decay of the atoms. The influence of the dissipation on fidelity and success probability of the three-qubit Toffoli gate is also discussed. The scheme can also be applied to realize an N-qubit Toffoli gate and the interaction time required does not rise with increasing the number of qubits.展开更多
We propose a scheme for realization a quantum Controlled-NOT gate operation using two four-level atoms through a selective atom cavity interaction in cavity quantum electrodynamics system. In our protocol, the quantum...We propose a scheme for realization a quantum Controlled-NOT gate operation using two four-level atoms through a selective atom cavity interaction in cavity quantum electrodynamics system. In our protocol, the quantum information is encoded on the stable ground states of the two atoms. During the interaction between atoms and single-mode vacuum cavity-field, the atomic spontaneous emission is negligible as the large atom-cavity detuning effectively suppresses the spontaneous decay of the atoms. The influences of the dissipation and the deviation of interaction time on fidelity and corresponding success probability of the quantum Controlled-NOT gate and the experimental feasibility of our proposal are also discussed.展开更多
We propose a scheme for teleportation of four-level atomic states in thermal cavities. The scheme does not involve the generalized Bell-state or generalized GHZ-state measurement, which is difficult in practice. Anoth...We propose a scheme for teleportation of four-level atomic states in thermal cavities. The scheme does not involve the generalized Bell-state or generalized GHZ-state measurement, which is difficult in practice. Another feature of the scheme is that it does not require individual addressing of atoms in cavity and is insensitive to both cavity decay and thermal field, which is of importance in point of experiment.展开更多
The spontaneous emission decay dynamics of a tripod configuration four-level atom driven by a single laser field is studied. Under different initial conditions, we discuss the effects of quantum interference and detun...The spontaneous emission decay dynamics of a tripod configuration four-level atom driven by a single laser field is studied. Under different initial conditions, we discuss the effects of quantum interference and detuning of external driving field on atomic spontaneous emission properties. For the larger detuning, the interesting phenomena of the spectral line narrowing are found which stem from the contribution of external driving field.展开更多
We have investigated the two-dimensional （2D） atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found th...We have investigated the two-dimensional （2D） atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of 2D atom localization can be significantly improved via adjusting the system parameters. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization.展开更多
The electromagnetically induced grating effect in thermal and cold atoms has been studied theoretically. Studies have shown that, by adjusting the parameters, the first-order diffraction efficiency of the probe beam i...The electromagnetically induced grating effect in thermal and cold atoms has been studied theoretically. Studies have shown that, by adjusting the parameters, the first-order diffraction efficiency of the probe beam in the cold atomic system and the thermal atomic system is 34% and 31%, respectively, which is very close to the ideal diffraction efficiency of the sinusoidal grating. However, it is more difficult to prepare the cold atomic system than to prepare the thermal atomic system in the practical application, so the study of the electromagnetically induced grating effect in the thermal atomic system may be helpful for practical applications.展开更多
Rydberg atoms have been widely investigated due to their large size,long radiative lifetime,huge polarizability and strong dipole-dipole interactions.The position information of Rydberg atoms provides more possibiliti...Rydberg atoms have been widely investigated due to their large size,long radiative lifetime,huge polarizability and strong dipole-dipole interactions.The position information of Rydberg atoms provides more possibilities for quantum optics research,which can be obtained under the localization method.We study the behavior of three-dimensional(3D)Rydberg atom localization in a four-level configuration with the measurement of the spatial optical absorption.The atomic localization precision depends strongly on the detuning and Rabi frequency of the involved laser fields.A 100%probability of finding the Rydberg atom at a specific 3D position is achieved with precision of~0.031λ.This work demonstrates the possibility for achieving the 3D atom localization of the Rydberg atom in the experiment.展开更多
We have investigated the dispersive properties of excited-doublet four-level atoms interacting with a weak probe field and an intense coupling laser field. We have derived an analytical expression of the dispersion re...We have investigated the dispersive properties of excited-doublet four-level atoms interacting with a weak probe field and an intense coupling laser field. We have derived an analytical expression of the dispersion relation for a general excited-doublet four-level atomic system subject to a one-photon detuning. The numerical results demonstrate that for a typical rubidium D1 line configuration, due to the unequal dipole moments for the transitions of each ground state to double excited states, generally there exists no exact dark state in the system. Close to the two-photon resonance, the probe light can be absorbed or gained and propagate in the so-called superluminal form. This system may be used as an optical switch.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
A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,...A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,γ-difluoro-and γ-monofluoro-vinylacetic acids without stepwise acidification,exhibiting good functional group tolerance,broad scope,and facile scalability.Mechanism studies support that thiol plays the role of the hydrogen relay,which s a hydrogen atom through HAT and then outputs a proton via PT.This strategy also takes full advantage of formate for photocatalytic carboxylation reaction in a step-and atomeconomical way.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
The dissolvable polysulfides and sluggish Li_2S conversion kinetics are acknowledged as two significant challenges in the application lithium-sulfur(Li-S)batteries.Herein,we introduce a dual-doping strategy to modulat...The dissolvable polysulfides and sluggish Li_2S conversion kinetics are acknowledged as two significant challenges in the application lithium-sulfur(Li-S)batteries.Herein,we introduce a dual-doping strategy to modulate the electronic structure of MoS_(2),thereby obtaining a multifunctional catalyst that serves as an efficient sulfur host.The W/V dual single-atomdoped MoS_(2)grown on carbon nanofibers(CMWVS)demonstrates a strong adsorption ability for lithium polysulfides,suppressing the shuttle effects.Additionally,the doping process also results in the phase transition from 2H-MoS_(2)to 1T-MoS_(2)and generates sufficient edge sulfur atoms,promoting the charge/electron transfer and enriching the reaction sites.All these merits contribute to the superior conversion reaction kinetics,leading to the outstanding Li-S battery performance.When fabricated as cathodes by compositing with sulfur,the CMWVS/S cathode delivers a high capacity of 1481.7 mAh g^(-1)at 0.1 C(1 C=1672 mAh g^(-1))and maintains 816.3 m Ah g^(-1)after 1000 cycles at 1.0 C,indicating outstanding cycling stability.Even under a high sulfur loading of 7.9 mg cm^(-2)and lean electrolyte conditions(E/S ratio of 9.0μL mg^(-1)),the cathode achieves a high areal capacity of 8.2 m Ah cm^(-2),showing great promise for practical Li-S battery applications.This work broadens the scope of doping strategies in transition-metal dichalcogenides by tailoring their electronic structures,providing insightful direction for the rational development of high-efficiency electrocatalysts for advanced Li-S battery applications.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
In science and technology,precision measurement of physical quantities is crucial,and the quantum Fisher information(QFI)plays a significant role in the study of quantum systems.In this work,we explore the dynamics of...In science and technology,precision measurement of physical quantities is crucial,and the quantum Fisher information(QFI)plays a significant role in the study of quantum systems.In this work,we explore the dynamics of QFI in a hybrid optomechanical system,which consists of a◇-type four-level atom interacting with a single-mode quantized field via a multi-photon process.We account for various sources of dissipation,including the decay rates of the atom,the cavity and the mechanical modes.Using an effective Hamiltonian,we analytically derive the explicit form of the state vector of the entire system via the time-dependent Schr?dinger equation.We then investigate the atomic QFI for the estimation precision of the decay rate of the mechanical oscillator.Furthermore,we examine how optomechanical and atom-field coupling strengths,dissipation parameters and multi-photon transition influence the dynamics of atomic QFI.Our numerical results suggest that the estimation precision of the decay rate of the mechanical oscillator can be controlled by these parameters.展开更多
We discuss and analyze the absorption properties of a weak probe field in a typical four-level atomic system in the presence of a spontaneously generated coherence (SGC) term. The influences of the SGC and a coherent ...We discuss and analyze the absorption properties of a weak probe field in a typical four-level atomic system in the presence of a spontaneously generated coherence (SGC) term. The influences of the SGC and a coherent pump field on the probe absorption-amplification are investigated. The results show that the absorption of such a weak probe field can be dramatically enhanced due to the SGC effect. At the same time, the probe-absorption profile exhibits a two-peak structure and the probe-absorption peak gradually decreases as the pump intensity increases. On the contrary, the amplification of such a weak probe field near the line center of the probe transition can be achieved by adjusting the coherent pump field intensity in the absence of the SGC effect.展开更多
We investigate high-precision three-dimensional （3D） atom localization in a coherently-driven, four- level atomic system via spontaneous emission. Space-dependent atom-field interactions allow atomic position inform...We investigate high-precision three-dimensional （3D） atom localization in a coherently-driven, four- level atomic system via spontaneous emission. Space-dependent atom-field interactions allow atomic position information to be obtained by measuring parameters, atoms within a certain range can be spontaneous emission. By properly varying system localized with nearly a probability of 100% and a maximal resolution of -0.04λ. This scheme may be useful for the high-precision measurement of the center-of-mass wave functions of moving atoms and in atom nanolithography.展开更多
We investigate theoretically two-photon absorption spectroscopy modified by a control field in a confined Y-type four-level system. Dicke-narrowing effect occurs both in two-photon absorption lines and the dips of tra...We investigate theoretically two-photon absorption spectroscopy modified by a control field in a confined Y-type four-level system. Dicke-narrowing effect occurs both in two-photon absorption lines and the dips of transparency against two-photon absorption due to enhanced contribution of slow atoms. We also find that the suppression and the enhancement of two-photon absorption can be modified by changing the strength of the control field and the detuning of three laser fields. This control of two-photon absorption may have some applications in information processing and optical devices.展开更多
It is shown that in a Doppler broadened open N-type four-level atomic system with spontaneously generated coherence (SGC), the gain without inversion (GWI) is very sensitive to the variation of the relative phase betw...It is shown that in a Doppler broadened open N-type four-level atomic system with spontaneously generated coherence (SGC), the gain without inversion (GWI) is very sensitive to the variation of the relative phase between the probe field and the driving field; the atomic exit rate (R0) and the ratio (S) of the atomic injection rates have a considerable modulation effect on the phase-dependent GWI. GWI first increases and then decreases with R0 increasing; in a certain value range of S, GWI increases monotonically with S increasing; by adjusting the values of R0 and S, in an open system a much larger GWI can be obtained than in the corresponding closed system [2011 Phys. Rev. A 83 043805]. The modulation effects of R0 and S on the phase-dependent GWI in the case with the counter-propagating probe and driving fields are stronger than those in the co-propagating case, GWI in the co-propagating case is much larger than that in the counter-propagating case.展开更多
Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish ...Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.展开更多
基金Project supported by the Natural Science Foundation of Hunan Province,China (Grant No 06JJ50118)
文摘This paper proposes a scheme for realization of a three-qubit Toffoli gate operation using three four-level atoms by a selective atom-field interaction in a cavity quantum electrodynamics system. In the proposed protocol, the quantum information is encoded on the stable ground states of atoms, and atomic spontaneous emission is negligible as the large atom-avity detuning effectively suppresses the spontaneous decay of the atoms. The influence of the dissipation on fidelity and success probability of the three-qubit Toffoli gate is also discussed. The scheme can also be applied to realize an N-qubit Toffoli gate and the interaction time required does not rise with increasing the number of qubits.
基金supported by the Natural Science Foundation of Hunan Province under Grant No.06JJ50118
文摘We propose a scheme for realization a quantum Controlled-NOT gate operation using two four-level atoms through a selective atom cavity interaction in cavity quantum electrodynamics system. In our protocol, the quantum information is encoded on the stable ground states of the two atoms. During the interaction between atoms and single-mode vacuum cavity-field, the atomic spontaneous emission is negligible as the large atom-cavity detuning effectively suppresses the spontaneous decay of the atoms. The influences of the dissipation and the deviation of interaction time on fidelity and corresponding success probability of the quantum Controlled-NOT gate and the experimental feasibility of our proposal are also discussed.
基金The project supported by the Scientific Research Fund of Education Department of Hunan Province of China under Grant No. 06C354, the Natural Science Foundation of Hunan Province of China under Grant No. 06JJ50015
文摘We propose a scheme for teleportation of four-level atomic states in thermal cavities. The scheme does not involve the generalized Bell-state or generalized GHZ-state measurement, which is difficult in practice. Another feature of the scheme is that it does not require individual addressing of atoms in cavity and is insensitive to both cavity decay and thermal field, which is of importance in point of experiment.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10904025,10674037 and 50836002)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20092302120024)+3 种基金the China Postdoctoral Science Foundation (Grant No. 20090451007)the Development Program for Outstanding Young Teachers in Harbin Institute of Technology,China (Grant No. HITQNJS. 2009. 030.)the National Basic Research Program of China (Grant No. 2007CB307001)the Program of Excellent Team in Harbin Institute of Technology China
文摘The spontaneous emission decay dynamics of a tripod configuration four-level atom driven by a single laser field is studied. Under different initial conditions, we discuss the effects of quantum interference and detuning of external driving field on atomic spontaneous emission properties. For the larger detuning, the interesting phenomena of the spectral line narrowing are found which stem from the contribution of external driving field.
基金the National Natural Science Foundation of China(Grant No.11205001)the National Basic Research Program of China(Grant No.2010CB234607)the Postdoctoral Science Foundation of Anhui University,China
文摘We have investigated the two-dimensional （2D） atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of 2D atom localization can be significantly improved via adjusting the system parameters. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization.
基金supported by the National Natural Science Foundation of China(Grants Nos.11004126 and 61275212)the Natural Science Foundation of Shanxi Province,China(Grant No.2011021003-1)
文摘The electromagnetically induced grating effect in thermal and cold atoms has been studied theoretically. Studies have shown that, by adjusting the parameters, the first-order diffraction efficiency of the probe beam in the cold atomic system and the thermal atomic system is 34% and 31%, respectively, which is very close to the ideal diffraction efficiency of the sinusoidal grating. However, it is more difficult to prepare the cold atomic system than to prepare the thermal atomic system in the practical application, so the study of the electromagnetically induced grating effect in the thermal atomic system may be helpful for practical applications.
基金the National R&D Program of China(Grant No.2017YFA0304203)the National Natural Science Foundation of China(Grant Nos.61875112,61705122,62075121,and 91736209)+1 种基金the Program for Sanjin Scholars of Shanxi Province,the Key Research and Development Program of Shanxi Province for International Cooperation(Grant No.201803D421034)Shanxi Scholarship Council of China(Grant Nos.2020-073),and 1331KSC.
文摘Rydberg atoms have been widely investigated due to their large size,long radiative lifetime,huge polarizability and strong dipole-dipole interactions.The position information of Rydberg atoms provides more possibilities for quantum optics research,which can be obtained under the localization method.We study the behavior of three-dimensional(3D)Rydberg atom localization in a four-level configuration with the measurement of the spatial optical absorption.The atomic localization precision depends strongly on the detuning and Rabi frequency of the involved laser fields.A 100%probability of finding the Rydberg atom at a specific 3D position is achieved with precision of~0.031λ.This work demonstrates the possibility for achieving the 3D atom localization of the Rydberg atom in the experiment.
基金supported by the Knowledge Innovation Program (KIP) of the Chinese Academy of Sciences (Grant No KGCX3-SYW-405)the National Fundamental Research Program of China (Grant Nos 2005CB724507 and 2006CB921202)
文摘We have investigated the dispersive properties of excited-doublet four-level atoms interacting with a weak probe field and an intense coupling laser field. We have derived an analytical expression of the dispersion relation for a general excited-doublet four-level atomic system subject to a one-photon detuning. The numerical results demonstrate that for a typical rubidium D1 line configuration, due to the unequal dipole moments for the transitions of each ground state to double excited states, generally there exists no exact dark state in the system. Close to the two-photon resonance, the probe light can be absorbed or gained and propagate in the so-called superluminal form. This system may be used as an optical switch.
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 National Natural Science Foundation of China (22472031,U24A20567,22032002)the 111 Project。
文摘A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,γ-difluoro-and γ-monofluoro-vinylacetic acids without stepwise acidification,exhibiting good functional group tolerance,broad scope,and facile scalability.Mechanism studies support that thiol plays the role of the hydrogen relay,which s a hydrogen atom through HAT and then outputs a proton via PT.This strategy also takes full advantage of formate for photocatalytic carboxylation reaction in a step-and atomeconomical way.
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 the National Natural Science Foundation of China(52402166)the Science and Technology Development Fund+2 种基金Macao SAR(0065/2023/AFJ,0116/2022/A3)the Australian Research Council(DE220100154)the Natural Science Foundation of Guangdong Province(2025A1515011120)。
文摘The dissolvable polysulfides and sluggish Li_2S conversion kinetics are acknowledged as two significant challenges in the application lithium-sulfur(Li-S)batteries.Herein,we introduce a dual-doping strategy to modulate the electronic structure of MoS_(2),thereby obtaining a multifunctional catalyst that serves as an efficient sulfur host.The W/V dual single-atomdoped MoS_(2)grown on carbon nanofibers(CMWVS)demonstrates a strong adsorption ability for lithium polysulfides,suppressing the shuttle effects.Additionally,the doping process also results in the phase transition from 2H-MoS_(2)to 1T-MoS_(2)and generates sufficient edge sulfur atoms,promoting the charge/electron transfer and enriching the reaction sites.All these merits contribute to the superior conversion reaction kinetics,leading to the outstanding Li-S battery performance.When fabricated as cathodes by compositing with sulfur,the CMWVS/S cathode delivers a high capacity of 1481.7 mAh g^(-1)at 0.1 C(1 C=1672 mAh g^(-1))and maintains 816.3 m Ah g^(-1)after 1000 cycles at 1.0 C,indicating outstanding cycling stability.Even under a high sulfur loading of 7.9 mg cm^(-2)and lean electrolyte conditions(E/S ratio of 9.0μL mg^(-1)),the cathode achieves a high areal capacity of 8.2 m Ah cm^(-2),showing great promise for practical Li-S battery applications.This work broadens the scope of doping strategies in transition-metal dichalcogenides by tailoring their electronic structures,providing insightful direction for the rational development of high-efficiency electrocatalysts for advanced Li-S battery applications.
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.
文摘In science and technology,precision measurement of physical quantities is crucial,and the quantum Fisher information(QFI)plays a significant role in the study of quantum systems.In this work,we explore the dynamics of QFI in a hybrid optomechanical system,which consists of a◇-type four-level atom interacting with a single-mode quantized field via a multi-photon process.We account for various sources of dissipation,including the decay rates of the atom,the cavity and the mechanical modes.Using an effective Hamiltonian,we analytically derive the explicit form of the state vector of the entire system via the time-dependent Schr?dinger equation.We then investigate the atomic QFI for the estimation precision of the decay rate of the mechanical oscillator.Furthermore,we examine how optomechanical and atom-field coupling strengths,dissipation parameters and multi-photon transition influence the dynamics of atomic QFI.Our numerical results suggest that the estimation precision of the decay rate of the mechanical oscillator can be controlled by these parameters.
文摘We discuss and analyze the absorption properties of a weak probe field in a typical four-level atomic system in the presence of a spontaneously generated coherence (SGC) term. The influences of the SGC and a coherent pump field on the probe absorption-amplification are investigated. The results show that the absorption of such a weak probe field can be dramatically enhanced due to the SGC effect. At the same time, the probe-absorption profile exhibits a two-peak structure and the probe-absorption peak gradually decreases as the pump intensity increases. On the contrary, the amplification of such a weak probe field near the line center of the probe transition can be achieved by adjusting the coherent pump field intensity in the absence of the SGC effect.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 11674002） and Doctoral Scientific Research Fund of Anhui University.
文摘We investigate high-precision three-dimensional （3D） atom localization in a coherently-driven, four- level atomic system via spontaneous emission. Space-dependent atom-field interactions allow atomic position information to be obtained by measuring parameters, atoms within a certain range can be spontaneous emission. By properly varying system localized with nearly a probability of 100% and a maximal resolution of -0.04λ. This scheme may be useful for the high-precision measurement of the center-of-mass wave functions of moving atoms and in atom nanolithography.
基金supported by the National Natural Science Foundation of China (No. 10874139) the Major Program of Science Foundation of Xi’an University of Arts and Science
文摘We investigate theoretically two-photon absorption spectroscopy modified by a control field in a confined Y-type four-level system. Dicke-narrowing effect occurs both in two-photon absorption lines and the dips of transparency against two-photon absorption due to enhanced contribution of slow atoms. We also find that the suppression and the enhancement of two-photon absorption can be modified by changing the strength of the control field and the detuning of three laser fields. This control of two-photon absorption may have some applications in information processing and optical devices.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11175105)
文摘It is shown that in a Doppler broadened open N-type four-level atomic system with spontaneously generated coherence (SGC), the gain without inversion (GWI) is very sensitive to the variation of the relative phase between the probe field and the driving field; the atomic exit rate (R0) and the ratio (S) of the atomic injection rates have a considerable modulation effect on the phase-dependent GWI. GWI first increases and then decreases with R0 increasing; in a certain value range of S, GWI increases monotonically with S increasing; by adjusting the values of R0 and S, in an open system a much larger GWI can be obtained than in the corresponding closed system [2011 Phys. Rev. A 83 043805]. The modulation effects of R0 and S on the phase-dependent GWI in the case with the counter-propagating probe and driving fields are stronger than those in the co-propagating case, GWI in the co-propagating case is much larger than that in the counter-propagating case.
基金Institute of Technology Research Fund Program for Young Scholars21C Innovation Laboratory Contemporary Amperex Technology Co.,Limited,Ninde, 352100, China (21C–OP-202314)。
文摘Lithium-sulfur (Li-S) batteries have gained great attention due to the high theoretical energy density and low cost,yet their further commercialization has been obstructed by the notorious shuttle effect and sluggish redox dynamics.Herein,we supply a strategy to optimize the electron structure of Ni_(2)P by concurrently introducing B-doped atoms and P vacancies in Ni_(2)P (Vp-B-Ni_(2)P),thereby enhancing the bidirectional sulfur conversion.The study indicates that the simultaneous introduction of B-doped atoms and P vacancies in Ni_(2)P causes the redistribution of electron around Ni atoms,bringing about the upward shift of d-band center of Ni atoms and effective d-p orbital hybridization between Ni atoms and sulfur species,thus strengthening the chemical anchoring for lithium polysulfides (LiPSs) as well as expediting the bidirectional conversion kinetics of sulfur species.Meanwhile,theoretical calculations reveal that the incorporation of B-doped atoms and P vacancies in Ni_(2)P selectively promotes Li2S dissolution and nucleation processes.Thus,the Li-S batteries with Vp-B-Ni_(2)P-separators present outstanding rate ability of 777 m A h g^(-1)at 5 C and high areal capacity of 8.03 mA h cm^(-2)under E/S of 5μL mg^(-1)and sulfur loading of 7.20 mg cm^(-2).This work elucidates that introducing heteroatom and vacancy in metal phosphide collaboratively regulates the electron structure to accelerate bidirectional sulfur conversion.
