查看更多>>摘要：The synthetic Floquet lattice,generated by multiple strong drives with mutually incommensurate frequencies,provides a powerful platform for quantum simulation of topological phenomena.In this study,we propose a 4-band tight-binding model of the Chern insulator with a Chern number C=±2 by coupling two layers of the half Bernevig-Hughes-Zhang lattice and subsequently mapping it onto the Floquet lattice to simulate its topological properties.To determine the Chern number of our Floquet-version model,we extend the energy pumping method proposed by Martin et al.[2017 Phys.Rev.X 7 041008]and the topological oscillation method introduced by Boyers et al.[2020 Phys.Rev.Lett.125 160505],followed by numerical simulations for both methodologies.The simulation results demonstrate the successful extraction of the Chern number using either of these methods,providing an excellent prediction of the phase diagram that closely aligns with the theoretical one derived from the original bilayer half Bernevig-Hughes-Zhang model.Finally,we briefly discuss a potential experimental implementation for our model.Our work demonstrates significant potential for simulating complex topological matter using quantum computing platforms,thereby paving the way for constructing a more universal simulator for non-interacting topological quantum states and advancing our understanding of these intriguing phenomena.
查看更多>>摘要：We present a novel approach for generating stable three-dimensional(3D)spatiotemporal solitons(SSs)within a rotating Bose-Einstein condensate,incorporating spin-orbit coupling(SOC),a weakly anharmonic potential and cold Rydberg atoms.This intricate system facilitates the emergence of quasi-stable 3D SSs with topological charges|m|≤ 3 in two spinor components,potentially exhibiting diverse spatial configurations.Our findings reveal that the Rydberg long-range interaction,spin-orbit coupling,and rotational angular frequency exert significant influence on the domains of existence and stability of these solitons.Notably,the Rydberg interaction contributes to a reduction in the norm of topological solitons,while the SOC plays a key role in stabilizing the SSs with finite topological charges.This research of SSs exhibits potential applications in precision measurement,quantum information processing,and other advanced technologies.
查看更多>>摘要：Spinor Bose-Einstein condensates(BECs)are formed when atoms in the multi-component BECs possess single hyperfine spin states but retain internal spin degrees of freedom.This study concentrates on a(1+1)-dimensional three-couple Gross-Pitaevskii system to depict the macroscopic spinor BEC waves within the mean-field approximation.Regarding the distribution of the atoms corresponding to the three vertical spin projections,a known binary Darboux transformation is utilized to derive the N matter-wave soliton solutions and triple-pole matter-wave soliton solutions on the zero background,where N is a positive integer.For those multiple matter-wave solitons,the asymptotic analysis is performed to obtain the algebraic expressions of the soliton components in the N matter-wave solitons and triple-pole matter-wave solitons.The asymptotic results indicate that the matter-wave solitons in the spinor BECs possess the property of maintaining their energy content and coherence during the propagation and interactions.Particularly,in the N matter-wave solitons,each soliton component contributes to the phase shifts of the other soliton components;and in the triple-pole matter-wave solitons,stable attractive forces exist between the different matter-wave soliton components.Those multiple matter-wave solitons are graphically illustrated through three-dimensional plots,density plot and contour plot,which are consistent with the asymptotic analysis results.The present analysis may provide the explanations for the complex natural mechanisms of the matter waves in the spinor BECs,and may have potential applications in designs of atom lasers,atom interferometry and coherent atom transport.
查看更多>>摘要：Pc(4457)has been discovered over five years,but the parity of this particle remains undetermined.We propose a new interpretation for Pc(4457),which is the state generated from the coupled-channel(D)0Λc+(2595)and π0Pc(4312)since they can exchange an almost on-shell ∑+c.In this scenario,the parity of Pc(4457)will be positive,which is different from the candidate of the bound state of(D)*∑c.The main decay channel of Pc(4457)in this model is Pc(4312)π.We propose three processes A0b → J/ψKspπ-,Λ0b → J/ψK-pπ0,and A0b → J/ψpπ-π+K-to verify Pc(4457)→ Pc(4312)π.
查看更多>>摘要：Metal-free organic emitters,characterized by their thermally activated delayed fluorescence(TADF)proper-ties,offer considerable promise for the creation of highly efficient organic light-emitting diodes(OLEDs).Recently,Shao et al.presented a novel excited state intramolecular proton transfer(ESIPT)system BrA-HBI,demonstrat-ing an emission quantum yield of up to 50％[Adv.Funct.Mater.32,2201256(2022)].However,many open issues cannot be answered solely by experimental means only and require detailed theoretical investigations.For instance,what causes the activation of TADF from the Keto*tautomer and leads to fluorescence quenching in the Enol*form?Herein,we provide a theoretical investigation on the TADF mechanism of the BrA-HBI molecule by optimally tuned range-separated functionals.Our findings reveal that ESIPT occurs in the BrA-HBI molecule.Moreover,we have disclosed the reason for the fluorescence quenching of the Enol*form and determined that the T2 state plays a dominant role in the TADF phenomenon.In addition,double hybrid density functionals method was utilized to verify the reliability of optimally tuned range separation functionals on the calculation of the TADF mechanism in BrA-HBI.These findings not only provide a theoretical reference for development of highly efficient organic light-emitting diodes,but also demonstrate the effectiveness of the optimally tuned range-separated functionals in predicting the luminescence properties of TADF molecules.
查看更多>>摘要：Cylindrical vector beams(CVBs)hold significant promise in mode division multiplexing communication owing to their inherent vector mode orthogonality.However,existing studies for facilitating CVB channel processing are confined to mode shift conversions due to their reliance on spin-dependent helical modulations,overlooking the pursuit of mode multiplication conversion.This challenge lies in the multiplicative operation upon inhomo-geneous vector mode manipulation,which is expected to advance versatile CVB channel switching and routing.Here,we tackle this gap by introducing a raytracing control strategy that conformally maps the light rays of CVB from the whole annulus distribution to an annular sector counterpart.Incorporated with the multifold conformal annulus-sector mappings and polarization-insensitive phase modulations,this approach facilitates the parallel transformation of input CVB into multiple complementary components,enabling the mode multiplica-tion conversion with protected vector structure.Serving as a demonstration,we experimentally implemented the multiplicative operation of four CVB modes with the multiplier factors of N=+2 and N=-3,achieving the converted mode purities over 94.24％and 88.37％.Subsequently,200 Gbit/s quadrature phase shift keying signals were successfully transmitted upon multiplicative switching of four CVB channels,with the bit-error-rate approaching 1 x 10-6.These results underscore our strategy's efficacy in CVB mode multiplication,which may open promising prospects for its advanced applications.
查看更多>>摘要：Materials for deep-ultraviolet(DUV)light emission are extremely rare,significantly limiting the development of efficient DUV light-emitting diodes.Here we report CsMg(I1-xBrx)3 alloys as potential DUV light emitters.Based on rigorous first-principles hybrid functional calculations,we find that CsMgI3 has an indirect bandgap,while CsMgBr3 has a direct bandgap.Further,we employ a band unfolding technique for alloy supercell cal-culations to investigate the critical Br concentration in CsMg(I1-xBrx)3 associated with the crossover from an indirect to a direct bandgap,which is found to be～0.36.Thus,CsMg(I1-xBrx)3 alloys with 0.36 ≤ x ≤ 1 cover a wide range of direct bandgap(4.38-5.37eV;284-231 nm),falling well into the DUV regime.Our study will guide the development of efficient DUV light emitters.
查看更多>>摘要：By systematic theoretical calculations,we reveal an excitonic insulator(EI)in the Ta2Pd3Te5 monolayer.The bulk Ta2Pd3Te5 is a van der Waals(vdW)layered compound,whereas the vdW layer can be obtained through exfoliation or molecular-beam epitaxy.First-principles calculations show that the monolayer is a nearly zero-gap semiconductor with the modified Becke-Johnson functional.Due to the same symmetry of the band-edge states,the two-dimensional polarization α2D would be finite as the band gap goes to zero,allowing for an EI state in the compound.Using the first-principles many-body perturbation theory,the GW plus Bethe-Salpeter equation calculation reveals that the exciton binding energy is larger than the single-particle band gap,indicating the excitonic instability.The computed phonon spectrum suggests that the monolayer is dynamically stable without lattice distortion.Our findings suggest that the Ta2Pd3Te5 monolayer is an excitonic insulator without structural distortion.
查看更多>>摘要：As an earth-abundant and environmentally friendly material,tin sulfide(SnS)is not only a high-performance photovoltaic material,but also a new promising thermoelectric material.Despite extensive research on the thermoelectric properties of this material in recent years,the room-temperature thermoelectric figure of merit(ZT)of SnS has not been broke through 2[2022 Sci.China Mater.65 1143].In this work,based on a combination of density functional theory and non-equilibrium Green's function method,the electronic and thermoelectric properties in SnS-nanoribbon-based heterojunctions are studied.The results show that although SnS nanoribbons(SNSNRs)with zigzag edges(ZSNSNRs)and armchair edges(ASNSNRs)both have semiconductor properties,the bandgaps of ASNSNRs are much wider than those of ZSNSNRs,which induces much wider conductance gaps of N-ASNSNR(N is the number of tin-sulfide lines across the ribbon width)).In the positive energy region,the ZT peaks of L-SNS-Au are much larger than those of L-SNS-GNR(L represents the number of longitudinal repeating units of SNSNR in the scattering region).While in the positive energy region,the ZT peaks of L-SNS-GNR are larger than those of L-SNS-Au.Further calculations reveal that the figure of merit will be over 3.7 in L-SNS-Au and 2.2 in L-SNS-GNR at room temperature,and over 4 in L-SNS-Au and 2.6 in L-SNS-GNR at 500 K.
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