By quenching the interatomic interactions, we investigate the nonequilibrium dynamics of two-dimensional Bose–Einstein condensates in boxlike traps with power-law potential boundaries. We show that ring dark solitons...By quenching the interatomic interactions, we investigate the nonequilibrium dynamics of two-dimensional Bose–Einstein condensates in boxlike traps with power-law potential boundaries. We show that ring dark solitons can be excited during the quench dynamics for both concave and convex potentials. The quench's modulation strength and the steepness of the boundary are two major factors influencing the system's evolution. In terms of the number of ring dark solitons excited in the condensate, five dynamic regimes have been identified. The condensate undergoes damped radius oscillation in the absence of ring dark soliton excitations. When it comes to the appearance of ring dark solitons, their decay produces interesting structures. The excitation patterns for the concave potential show a nested structure of vortex-antivortex pairs. The dynamic excitation patterns for the convex potential, on the other hand, show richer structures with multiple transport behaviors.展开更多
Short-time critical behavior of the random n-vector model is studied by the theoretic renormalization-group approach.Asymptotic scaling laws are studied in a frame of the expansion in e = 4 - d for n ≠ 1 and for n = ...Short-time critical behavior of the random n-vector model is studied by the theoretic renormalization-group approach.Asymptotic scaling laws are studied in a frame of the expansion in e = 4 - d for n ≠ 1 and for n = 1respectively.In d ＜ 4,the initial slip exponents θ′ for the order parameter and θ for the response function are calculated up to the second order in e ＝ 4 - d for n ≠ 1 and for n ＝ 1 at the random fixed point respectively.Our results show that the random impurities exert a strong influence on the short-time dynamics for d ＜ 4 and n ＜ nc.展开更多
We investigate a periodically driven Haldane model subjected to a two-stage driving scheme in the form of a step function.By using the Floquet theory,we obtain the topological phase diagram of the system.We also find ...We investigate a periodically driven Haldane model subjected to a two-stage driving scheme in the form of a step function.By using the Floquet theory,we obtain the topological phase diagram of the system.We also find that anomalous Floquet topological phases exist in the system.Focusing on examining the quench dynamics among topological phases,we analyze the site distribution of the 0-mode and p-mode edge states in long-period evolution after a quench.The results demonstrate that,under certain conditions,the site distribution of the 0-mode can be confined at the edge even in long-period evolution.Additionally,both the 0-mode and p-mode can recover and become confined at the edge in long-period evolution when the post-quench parameters(T,M_(2) /M_(1))in the phase diagram cross away from the phase boundary (M_(2)/ M_(1))=(6√3t2)/ M_(1)−1.Furthermore,we conclude that whether the edge state is confined at the edge in the long-period evolution after a quench depends on the similarity of the edge states before and after the quench.Our findings reveal some new characteristics of quench dynamics in a periodically driven system.展开更多
Hydrogen peroxide(H_(2)O_(2))is extensively used in medical disinfection,water treatment,and environmental protection.To achieve the green synthesis of H_(2)O_(2),g-C_(3)N_(4)-based photocatalysis is an effective stra...Hydrogen peroxide(H_(2)O_(2))is extensively used in medical disinfection,water treatment,and environmental protection.To achieve the green synthesis of H_(2)O_(2),g-C_(3)N_(4)-based photocatalysis is an effective strategy and shows great potential.Nonetheless,single g-C_(3)N_(4)exhibits poor photocatalytic properties due to severe photogenerated charge recombination.To solve this challenge,this work enables F^(−)adsorption on the surface of g-C_(3)N_(4)nanotubes in solution driven by Coulomb forces through pH adjustment and the addition of NH4F.The photocatalytic H_(2)O_(2)production rate of the optimal F^(−)-decorated g-C_(3)N_(4)is three times higher than that of pure g-C_(3)N_(4),attributing to the synergistic effect of F^(−)and H^(+).Quenching experiments verify that the photocatalytic H_(2)O_(2)production process of CNF is a two-electron oxygen reduction process.Electron quenching dynamics of g-C_(3)N_(4)and CNF are revealed by femtosecond transient absorption spectroscopy(fs-TAS).Compared to pure g-C_(3)N_(4),CNF has an additional ultrashort lifetime(3.1 ps)representing the interfacial electron transfer from the conduction band of g-C_(3)N_(4)to F^(−).In situ fs-TAS results show that the interfacial electron transfer rate and electron utilization efficiency are respectively increased from 1.5×10^(8)s^(–1)and 19%in air to 5.0×10^(8)s^(-1)and 45%in O_(2) atmosphere with ethanol sacrificial agent.Hence,the O_(2),H^(+),and photogenerated electrons are key substances in the H_(2)O_(2)evolution.This work has elucidated the dynamics mechanism of enhanced photocatalytic performance of F^(−)-modified g-C_(3)N_(4)and provides inspiration for the design and synthesis of efficient g-C_(3)N_(4)-based photocatalysts.展开更多
CO2 pyrolysis by thermal plasma was investigated,and a high conversion rate of 33% and energy efficiency of 17% were obtained.The high performance benefited from a novel quenching method,which synergizes the convergin...CO2 pyrolysis by thermal plasma was investigated,and a high conversion rate of 33% and energy efficiency of 17% were obtained.The high performance benefited from a novel quenching method,which synergizes the converging nozzle and cooling tube.To understand the synergy effect,a computational fluid dynamics simulation was carried out.A quick quenching rate of 10~7Ks（-1） could be expected when the pyrolysis gas temperature decreased from more than 3000 to 1000 K.According to the simulation results,the quenching mechanism was discussed as follows： first,the compressible fluid was adiabatically expanded in the converging nozzle and accelerated to sonic speed,and parts of the heat energy converted to convective kinetic energy; second,the sonic fluid jet into the cooling tube formed a strong eddy,which greatly enhanced the heat transfer between the inverse-flowing fluid and cooling tube.These two mechanisms ensure a quick quenching to prevent the reverse reaction of CO2 pyrolysis gas when it flows out from the thermal plasma reactor.展开更多
Higher-order topological phases(HOTPs) are systems with topologically protected in-gap boundary states localized at their ed à nT-dimensional boundaries, with d the system dimension and n the order of the topolog...Higher-order topological phases(HOTPs) are systems with topologically protected in-gap boundary states localized at their ed à nT-dimensional boundaries, with d the system dimension and n the order of the topology. This work proposes a dynamics-based characterization of one large class of Z-type HOTPs without specifically relying on any crystalline symmetry considerations. The key element of our innovative approach is to connect quantum quench dynamics with nested configurations of the socalled band inversion surfaces(BISs) of momentum-space Hamiltonians as a sum of operators from the Clifford algebra(a condition that can be partially relaxed), thereby making it possible to dynamically detect each and every order of topology on an equal footing. Given that experiments on synthetic topological matter can directly measure the winding of certain pseudospin texture to determine topological features of BISs, the topological invariants defined through nested BISs are all within reach of ongoing experiments. Further, the necessity of having nested BISs in defining higher-order topology offers a unique perspective to investigate and engineer higher-order topological phase transitions.展开更多
The free-fermion topological phases with Z_(2)invariants cover a broad range of topological states,including the time-reversal invariant topological insulators,and are defined on the equilibrium ground states.Whether ...The free-fermion topological phases with Z_(2)invariants cover a broad range of topological states,including the time-reversal invariant topological insulators,and are defined on the equilibrium ground states.Whether such equilibrium topological phases have universal correspondence to far-from-equilibrium quantum dynamics is a fundamental issue of both theoretical and experimental importance.Here we uncover the universal topological quench dynamics linking to these equilibrium topological phases of different dimensionality and symmetry classes in the tenfold way,with a general framework being established.We show a novel result that a generic d-dimensional topological phase represented by Dirac type Hamiltonian and with Z_(2)invariant defined on high symmetry momenta can be characterized by topology reduced to certain arbitrary discrete momenta of Brillouin zone called the highest-order bandinversion surfaces.Such dimension-reduced topology has unique correspondence to the topological pattern emerging in far-from-equilibrium quantum dynamics by quenching the system from trivial phase to the topological regime,rendering the dynamical hallmark of the equilibrium topological phase.This work completes the dynamical characterization for the full tenfold classes of topological phases,which can be partially extended to even broader topological phases protected by lattice symmetries and in non-Dirac type systems,and shall advance widely the research in theory and experiment.展开更多
Recently universal dynamic scaling is observed in several systems,which exhibit a spatiotemporal self-similar scaling behavior,analogous to the spatial scaling near phase transition.The latter one arises from the emer...Recently universal dynamic scaling is observed in several systems,which exhibit a spatiotemporal self-similar scaling behavior,analogous to the spatial scaling near phase transition.The latter one arises from the emergent continuous scaling symmetry.Motivated by this,we investigate the possible relation between the scaling dynamics and the continuous scaling symmetry in this paper.We derive a theorem that the scaling invariance of the quenched Hamiltonian and the initial density matrix can lead to the universal dynamic scaling.It is further demonstrated both in a two-body system analytically and in a many-body system numerically.For the latter one,we calculate the dynamics of quantum gases quenched from the zero interaction to a finite interaction via the non-equilibrium high-temperature virial expansion.A dynamic scaling of the momentum distribution appears in certain momentum-time windows at unitarity as well as in the weak interacting limit.Remarkably,this universal scaling dynamics persists approximately with smaller scaling exponents even if the scaling symmetry is fairly broken.Our findings may offer a new perspective to interpret the related experiments.We also study the Contact dynamics in the BEC−BCS crossover.Surprisingly,the half-way time displays a maximum near unitarity while some damping oscillations occur on the BEC side due to the dimer state,which can be used to detect possible two-body bound states in experiments.展开更多
Pure ZnO exhibits low photocatalytic H_(2)O_(2)production activity due to the rapid charge recombination.To realize the spatial separation of photogenerated electrons and holes,constructing an electron transfer channe...Pure ZnO exhibits low photocatalytic H_(2)O_(2)production activity due to the rapid charge recombination.To realize the spatial separation of photogenerated electrons and holes,constructing an electron transfer channel on the ZnO surface is an effective approach.This study successfully modified the surface of ZnO using F^(-)(ZnO/F)by introducing NH4F in an aqueous phase photocatalytic system.The F^(-)is adsorbed on the ZnO surface by Coulombic force and significantly improves the photocatalytic H_(2)O_(2)production performance of ZnO,with the highest efficiency of 4137.2μmol,g·^(-1)·L^(-1)·h^(-1).The photocatalytic performance enhancement mechanism of ZnO/F is explained in terms of electron transfer dynamics by femtosecond transient absorption spectroscopy(fs-TAS)measurements.F^(-)surface modification constructs a new ultrafast electron transport pathway from the ZnO CB to F^(-),and the optimal ZnO/F exhibits the fastest interfacial electron transfer lifetime of 5.8 ps.The F^(-)surface modification effectively facilitates the charge separation,thereby increasing the number of electrons available for photocatalytic H_(2)O_(2)reaction.This study has revealed the roles of F^(-)surface modification in the photocatalytic H_(2)O_(2)production by ZnO and provides guidance for ionic modification to improve photocatalytic performance.展开更多
Emission quenching of [Ru(bpy)2(4, 4'-dcbpy)] (PF6)2 (1) by benzenamine,4-[2-[5-[4-[4-dimethylamino]phenyl]-4,5-di-hydro-1-phenyl-1H-pyrazol-3-yl]-ethenyl]-N,N-dimetyl (2) or 1, 5-diphenyl-3-(2-phenothiazine)-2-py...Emission quenching of [Ru(bpy)2(4, 4'-dcbpy)] (PF6)2 (1) by benzenamine,4-[2-[5-[4-[4-dimethylamino]phenyl]-4,5-di-hydro-1-phenyl-1H-pyrazol-3-yl]-ethenyl]-N,N-dimetyl (2) or 1, 5-diphenyl-3-(2-phenothiazine)-2-pyrazoline (3) was observed. Measurements of the emission decay of 1 before and after addition of 2 or 3 by single photon counting technique con-finned the observations. The emission quenching of 1 by 2 or 3 was submitted to Stern-Volmer equation. It was calculated that the quenching rate constants (kq) are 5.5 × 109(mol/L)-1s-1 for 2 and 4.0 × 109(mol/L)-1s-1 for 3, respectively. These results indicated a character of dynamic quenching process. The singlet-state of 2 or 3 was also quenched by 1. The quenching behaviors did not conform to the Stern- Volmer equation and involved both static and dynamic quenching processes. The apparent quenching rate constant (kapp) was calculated to be 3 × 109 (mol/L)-1 for the interaction of excited 2 with 1, and 1.2 × 109 (mol/L)-1 for that of excited 3 with 1.展开更多
There is an immense effort in search for various types of Weyl semimetals, of which the most fundamental phase consists of the minimal number of i.e. two Weyl points, but is hard to engineer in solids. Here we demonst...There is an immense effort in search for various types of Weyl semimetals, of which the most fundamental phase consists of the minimal number of i.e. two Weyl points, but is hard to engineer in solids. Here we demonstrate how such fundamental Weyl semimetal can be realized in a maneuverable optical Raman lattice, with which the three-dimensional(3D) spin-orbit(SO) coupling is synthesised for ultracold atoms. In addition, a new novel Weyl phase with coexisting Weyl nodal points and nodal ring is also predicted here, and is shown to be protected by nontrivial linking numbers. We further propose feasible techniques to precisely resolve 3D Weyl band topology through 2D equilibrium and dynamical measurements. This work leads to the first realization of the most fundamental Weyl semimetal band and the 3D SO coupling for ultracold quantum gases, which are respectively the significant issues in the condensed matter and ultracold atom physics.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 12175180, 11934015, and 11775178)the Major Basic Research Program of Natural Science of Shaanxi Province (Grant Nos. 2017KCT-12 and 2017ZDJC-32)the Double First-Class University Construction Project of Northwest University。
文摘By quenching the interatomic interactions, we investigate the nonequilibrium dynamics of two-dimensional Bose–Einstein condensates in boxlike traps with power-law potential boundaries. We show that ring dark solitons can be excited during the quench dynamics for both concave and convex potentials. The quench's modulation strength and the steepness of the boundary are two major factors influencing the system's evolution. In terms of the number of ring dark solitons excited in the condensate, five dynamic regimes have been identified. The condensate undergoes damped radius oscillation in the absence of ring dark soliton excitations. When it comes to the appearance of ring dark solitons, their decay produces interesting structures. The excitation patterns for the concave potential show a nested structure of vortex-antivortex pairs. The dynamic excitation patterns for the convex potential, on the other hand, show richer structures with multiple transport behaviors.
文摘Short-time critical behavior of the random n-vector model is studied by the theoretic renormalization-group approach.Asymptotic scaling laws are studied in a frame of the expansion in e = 4 - d for n ≠ 1 and for n = 1respectively.In d ＜ 4,the initial slip exponents θ′ for the order parameter and θ for the response function are calculated up to the second order in e ＝ 4 - d for n ≠ 1 and for n ＝ 1 at the random fixed point respectively.Our results show that the random impurities exert a strong influence on the short-time dynamics for d ＜ 4 and n ＜ nc.
基金the National Natural Science Foundation of China(Grant No.12004049).
文摘We investigate a periodically driven Haldane model subjected to a two-stage driving scheme in the form of a step function.By using the Floquet theory,we obtain the topological phase diagram of the system.We also find that anomalous Floquet topological phases exist in the system.Focusing on examining the quench dynamics among topological phases,we analyze the site distribution of the 0-mode and p-mode edge states in long-period evolution after a quench.The results demonstrate that,under certain conditions,the site distribution of the 0-mode can be confined at the edge even in long-period evolution.Additionally,both the 0-mode and p-mode can recover and become confined at the edge in long-period evolution when the post-quench parameters(T,M_(2) /M_(1))in the phase diagram cross away from the phase boundary (M_(2)/ M_(1))=(6√3t2)/ M_(1)−1.Furthermore,we conclude that whether the edge state is confined at the edge in the long-period evolution after a quench depends on the similarity of the edge states before and after the quench.Our findings reveal some new characteristics of quench dynamics in a periodically driven system.
基金financially supported by the National Natural Science Foundation of China(Nos.U23A20102,52202375,22469001,22261142666,and 22366028)the Natural Science Foundation of Hubei Province of China(No.2022CFA001)。
文摘Hydrogen peroxide(H_(2)O_(2))is extensively used in medical disinfection,water treatment,and environmental protection.To achieve the green synthesis of H_(2)O_(2),g-C_(3)N_(4)-based photocatalysis is an effective strategy and shows great potential.Nonetheless,single g-C_(3)N_(4)exhibits poor photocatalytic properties due to severe photogenerated charge recombination.To solve this challenge,this work enables F^(−)adsorption on the surface of g-C_(3)N_(4)nanotubes in solution driven by Coulomb forces through pH adjustment and the addition of NH4F.The photocatalytic H_(2)O_(2)production rate of the optimal F^(−)-decorated g-C_(3)N_(4)is three times higher than that of pure g-C_(3)N_(4),attributing to the synergistic effect of F^(−)and H^(+).Quenching experiments verify that the photocatalytic H_(2)O_(2)production process of CNF is a two-electron oxygen reduction process.Electron quenching dynamics of g-C_(3)N_(4)and CNF are revealed by femtosecond transient absorption spectroscopy(fs-TAS).Compared to pure g-C_(3)N_(4),CNF has an additional ultrashort lifetime(3.1 ps)representing the interfacial electron transfer from the conduction band of g-C_(3)N_(4)to F^(−).In situ fs-TAS results show that the interfacial electron transfer rate and electron utilization efficiency are respectively increased from 1.5×10^(8)s^(–1)and 19%in air to 5.0×10^(8)s^(-1)and 45%in O_(2) atmosphere with ethanol sacrificial agent.Hence,the O_(2),H^(+),and photogenerated electrons are key substances in the H_(2)O_(2)evolution.This work has elucidated the dynamics mechanism of enhanced photocatalytic performance of F^(−)-modified g-C_(3)N_(4)and provides inspiration for the design and synthesis of efficient g-C_(3)N_(4)-based photocatalysts.
基金the funding of National Natural Science Foundation of China (Grant No.11775155)
文摘CO2 pyrolysis by thermal plasma was investigated,and a high conversion rate of 33% and energy efficiency of 17% were obtained.The high performance benefited from a novel quenching method,which synergizes the converging nozzle and cooling tube.To understand the synergy effect,a computational fluid dynamics simulation was carried out.A quick quenching rate of 10~7Ks（-1） could be expected when the pyrolysis gas temperature decreased from more than 3000 to 1000 K.According to the simulation results,the quenching mechanism was discussed as follows： first,the compressible fluid was adiabatically expanded in the converging nozzle and accelerated to sonic speed,and parts of the heat energy converted to convective kinetic energy; second,the sonic fluid jet into the cooling tube formed a strong eddy,which greatly enhanced the heat transfer between the inverse-flowing fluid and cooling tube.These two mechanisms ensure a quick quenching to prevent the reverse reaction of CO2 pyrolysis gas when it flows out from the thermal plasma reactor.
基金the Singapore Ministry of Education Academic Research Fund Tier-3 Grant No.MOE2017T3-1-001(WBS.No.R-144-000-425-592)the Singapore National Research Foundation Grant No.NRF-NRFI2017-04(WBS No.R-144-000-378-281)。
文摘Higher-order topological phases(HOTPs) are systems with topologically protected in-gap boundary states localized at their ed à nT-dimensional boundaries, with d the system dimension and n the order of the topology. This work proposes a dynamics-based characterization of one large class of Z-type HOTPs without specifically relying on any crystalline symmetry considerations. The key element of our innovative approach is to connect quantum quench dynamics with nested configurations of the socalled band inversion surfaces(BISs) of momentum-space Hamiltonians as a sum of operators from the Clifford algebra(a condition that can be partially relaxed), thereby making it possible to dynamically detect each and every order of topology on an equal footing. Given that experiments on synthetic topological matter can directly measure the winding of certain pseudospin texture to determine topological features of BISs, the topological invariants defined through nested BISs are all within reach of ongoing experiments. Further, the necessity of having nested BISs in defining higher-order topology offers a unique perspective to investigate and engineer higher-order topological phase transitions.
基金supported by the National Key Research and Development Program of China(2021YFA1400900)the National Natural Science Foundation of China(11825401 and 11921005)+1 种基金the Open Project of Shenzhen Institute of Quantum Science and Engineering(SIQSE202003)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB28000000)。
文摘The free-fermion topological phases with Z_(2)invariants cover a broad range of topological states,including the time-reversal invariant topological insulators,and are defined on the equilibrium ground states.Whether such equilibrium topological phases have universal correspondence to far-from-equilibrium quantum dynamics is a fundamental issue of both theoretical and experimental importance.Here we uncover the universal topological quench dynamics linking to these equilibrium topological phases of different dimensionality and symmetry classes in the tenfold way,with a general framework being established.We show a novel result that a generic d-dimensional topological phase represented by Dirac type Hamiltonian and with Z_(2)invariant defined on high symmetry momenta can be characterized by topology reduced to certain arbitrary discrete momenta of Brillouin zone called the highest-order bandinversion surfaces.Such dimension-reduced topology has unique correspondence to the topological pattern emerging in far-from-equilibrium quantum dynamics by quenching the system from trivial phase to the topological regime,rendering the dynamical hallmark of the equilibrium topological phase.This work completes the dynamical characterization for the full tenfold classes of topological phases,which can be partially extended to even broader topological phases protected by lattice symmetries and in non-Dirac type systems,and shall advance widely the research in theory and experiment.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant No.12004049)the Fund of State Key Laboratory of IPOC(BUPT)(Nos.600119525 and 505019124).
文摘Recently universal dynamic scaling is observed in several systems,which exhibit a spatiotemporal self-similar scaling behavior,analogous to the spatial scaling near phase transition.The latter one arises from the emergent continuous scaling symmetry.Motivated by this,we investigate the possible relation between the scaling dynamics and the continuous scaling symmetry in this paper.We derive a theorem that the scaling invariance of the quenched Hamiltonian and the initial density matrix can lead to the universal dynamic scaling.It is further demonstrated both in a two-body system analytically and in a many-body system numerically.For the latter one,we calculate the dynamics of quantum gases quenched from the zero interaction to a finite interaction via the non-equilibrium high-temperature virial expansion.A dynamic scaling of the momentum distribution appears in certain momentum-time windows at unitarity as well as in the weak interacting limit.Remarkably,this universal scaling dynamics persists approximately with smaller scaling exponents even if the scaling symmetry is fairly broken.Our findings may offer a new perspective to interpret the related experiments.We also study the Contact dynamics in the BEC−BCS crossover.Surprisingly,the half-way time displays a maximum near unitarity while some damping oscillations occur on the BEC side due to the dimer state,which can be used to detect possible two-body bound states in experiments.
基金supported by National Natural Science Foundation of China(U23A20102,52202375,22469001)the Natural Science Foundation of Hubei Province of China(2022CFA001).
文摘Pure ZnO exhibits low photocatalytic H_(2)O_(2)production activity due to the rapid charge recombination.To realize the spatial separation of photogenerated electrons and holes,constructing an electron transfer channel on the ZnO surface is an effective approach.This study successfully modified the surface of ZnO using F^(-)(ZnO/F)by introducing NH4F in an aqueous phase photocatalytic system.The F^(-)is adsorbed on the ZnO surface by Coulombic force and significantly improves the photocatalytic H_(2)O_(2)production performance of ZnO,with the highest efficiency of 4137.2μmol,g·^(-1)·L^(-1)·h^(-1).The photocatalytic performance enhancement mechanism of ZnO/F is explained in terms of electron transfer dynamics by femtosecond transient absorption spectroscopy(fs-TAS)measurements.F^(-)surface modification constructs a new ultrafast electron transport pathway from the ZnO CB to F^(-),and the optimal ZnO/F exhibits the fastest interfacial electron transfer lifetime of 5.8 ps.The F^(-)surface modification effectively facilitates the charge separation,thereby increasing the number of electrons available for photocatalytic H_(2)O_(2)reaction.This study has revealed the roles of F^(-)surface modification in the photocatalytic H_(2)O_(2)production by ZnO and provides guidance for ionic modification to improve photocatalytic performance.
基金Project (Nos. 29971031, 29733100) supported by the National Natural Science Foundation of China.
文摘Emission quenching of [Ru(bpy)2(4, 4'-dcbpy)] (PF6)2 (1) by benzenamine,4-[2-[5-[4-[4-dimethylamino]phenyl]-4,5-di-hydro-1-phenyl-1H-pyrazol-3-yl]-ethenyl]-N,N-dimetyl (2) or 1, 5-diphenyl-3-(2-phenothiazine)-2-pyrazoline (3) was observed. Measurements of the emission decay of 1 before and after addition of 2 or 3 by single photon counting technique con-finned the observations. The emission quenching of 1 by 2 or 3 was submitted to Stern-Volmer equation. It was calculated that the quenching rate constants (kq) are 5.5 × 109(mol/L)-1s-1 for 2 and 4.0 × 109(mol/L)-1s-1 for 3, respectively. These results indicated a character of dynamic quenching process. The singlet-state of 2 or 3 was also quenched by 1. The quenching behaviors did not conform to the Stern- Volmer equation and involved both static and dynamic quenching processes. The apparent quenching rate constant (kapp) was calculated to be 3 × 109 (mol/L)-1 for the interaction of excited 2 with 1, and 1.2 × 109 (mol/L)-1 for that of excited 3 with 1.
基金supported by the National Natural Science Foundation of China (11825401, 11761161003, and 11921005)the National Key R&D Program of China (2016YFA0301604)Strategic Priority Research Program of CAS (XDB28000000)。
文摘There is an immense effort in search for various types of Weyl semimetals, of which the most fundamental phase consists of the minimal number of i.e. two Weyl points, but is hard to engineer in solids. Here we demonstrate how such fundamental Weyl semimetal can be realized in a maneuverable optical Raman lattice, with which the three-dimensional(3D) spin-orbit(SO) coupling is synthesised for ultracold atoms. In addition, a new novel Weyl phase with coexisting Weyl nodal points and nodal ring is also predicted here, and is shown to be protected by nontrivial linking numbers. We further propose feasible techniques to precisely resolve 3D Weyl band topology through 2D equilibrium and dynamical measurements. This work leads to the first realization of the most fundamental Weyl semimetal band and the 3D SO coupling for ultracold quantum gases, which are respectively the significant issues in the condensed matter and ultracold atom physics.
