A proposal for detecting weak electromagnetic waves around 2.6μm wavelength with Sr optical clock

Infrared signal detection is widely used in many fields.Due to the detection principle,however,the accuracy and range of detection are limited.Thanks to the ultra stability of the^(87)Sr optical lattice clock,external infrared electromagnetic wave disturbances can be responded to.Utilizing the ac Stark shift of the clock transition,we propose a new method to detect infrared signals.According to our calculations,the theoretical detection accuracy in the vicinity of its resonance band of 2.6μm can reach the order of 10-14W,while the minimum detectable signal of common detectors is on the order of 10^(-10)W.

Photoinduced Floquet higher-order Weyl semimetal in C_(6) symmetric Dirac semimetals

Topological Dirac semimetals are a parent state from which other exotic topological phases of matter, such as Weyl semimetals and topological insulators, can emerge. In this study, we investigate a Dirac semimetal possessing sixfold rotational symmetry and hosting higher-order topological hinge Fermi arc states, which is irradiated by circularly polarized light. Our findings reveal that circularly polarized light splits each Dirac node into a pair of Weyl nodes due to the breaking of time-reversal symmetry, resulting in the realization of the Weyl semimetal phase. This Weyl semimetal phase exhibits rich boundary states, including two-dimensional surface Fermi arc states and hinge Fermi arc states confined to six hinges.Furthermore, by adjusting the incident direction of the circularly polarized light, we can control the degree of tilt of the resulting Weyl cones, enabling the realization of different types of Weyl semimetals.

Active control of surface plasmon polaritons with phase change materials

Active control of surface plasmon polaritons(SPPs)is highly desired for nanophotonics.Here we employ a phase change material Ge_(2)Sb_(2)Te_(5)(GST)to actively manipulate the propagating direction of SPPs at the telecom wavelength.By utilizing the phase transition-induced refractive index change of GST,coupled with interference effects,a nanoantenna pair containing GST is designed to realize switchable one-way launching of SPPs.Devices based on the nanoantenna pairs are proposed to manipulate SPPs,including the direction tuning of SPP beams,switchable SPP focusing,and switchable cosine–Gauss SPP beam generating.Our design can be employed in compact optical circuits and photonics integration.

Application of Newtonian approximate model to LIGO gravitational wave data processing

With the observation of a series of ground-based laser interferometer gravitational wave(GW)detectors such as LIGO and Virgo,nearly 100 GW events have been detected successively.At present,all detected GW events are generated by the mergers of compact binary systems and are identified through the data processing of matched filtering.Based on matched filtering,we use the GW waveform of the Newtonian approximate(NA)model constructed by linearized theory to match the events detected by LIGO and injections to determine the coalescence time and utilize the frequency curve for data fitting to estimate the parameters of the chirp masses of binary black holes(BBHs).The average chirp mass of our results is 22.05_(-6.31)^(+6.31)M_(⊙),which is very close to 23.80_(-3.52)^(+4.83)M_(⊙)provided by GWOSC.In the process,we can analyze LIGO GW events and estimate the chirp masses of the BBHs.This work presents the feasibility and accuracy of the low-order approximate model and data fitting in the application of GW data processing.It is beneficial for further data processing and has certain research value for the preliminary application of GW data.

Nonadiabatic geometric phase in a doubly driven two-level system

We study theoretically the nonadiabatic geometric phase of a doubly driven two-level system with an additional relative phase between the two driving modes introduced in. It is shown that the time evolution of the system strongly depends on this relative phase. The condition for the system returning to its initial state after a single period is given by the means of the Landau–Zener–Stückelberg–Majorana destructive interference. The nonadiabatic geometric phase accompanying a cyclic evolution is shown to be related to the Stokes phase as well as this relative phase. By controlling the relative phase, the geometric phase can characterize two distinct phases in the adiabatic limit.

Majorana Corner Modes and Flat-Band Majorana Edge Modes in Superconductor/Topological-Insulator/Superconductor Junctions

Recently,superconductors with higher-order topology have stimulated extensive attention and research interest.Higher-order topological superconductors exhibit unconventional bulk-boundary correspondence,thus allow exotic lower-dimensional boundary modes,such as Majorana corner and hinge modes.However,higher-order topological superconductivity has yet to be found in naturally occurring materials.We investigate higher-order topology in a two-dimensional Josephson junction comprised of two s-wave superconductors separated by a topological insulator thin film.We find that zero-energy Majorana corner modes,a boundary fingerprint of higherorder topological superconductivity,can be achieved by applying magnetic field.When an in-plane Zeeman field is applied to the system,two corner modes appear in the superconducting junction.Furthermore,we also discover a two-dimensional nodal superconducting phase which supports flat-band Majorana edge modes connecting the bulk nodes.Importantly,we demonstrate that zero-energy Majorana corner modes are stable when increasing the thickness of topological insulator thin film.

The shadow and observation appearance of black hole surrounded by the dust field in Rastall theory

In the context of Rastall gravity,the shadow and observation intensity casted by the new Kiselev-like black hole with dust field have been numerically investigated.In this system,the Rastall parameter and surrounding dust field structure parameter have considerable consequences on the geometric structure of spacetime.Considering the photon trajectories near the black hole,we investigate the variation of the radii of photon sphere,event horizon and black hole shadow under the different related parameters.Furthermore,taking into account two different spherically symmetric accretion models as the only background light source,we also studied the observed luminosity and intensity of black holes.For the both spherical accretions background,the results show that the decrease or increase of the observed luminosity depends on the value range of relevant parameters,and the promotion effect is far less obvious than the attenuation effect on the observed intensity.One can find that the inner shadow region and outer bright region of the black hole wrapped by infalling accretion are significantly darker than those of the static model,which is closely related to the Doppler effect.In addition,the size of the shadow and the position of the photon sphere are always the same in the two accretion models,which means that the black hole shadow depend only on the geometry of spacetime,while the observation luminosity is affected by the form of accretion material and the related spacetime structure.

Novel and Self-Consistency Analysis of the QCD Running Coupling α_(s)(Q) in Both the Perturbative and Nonperturbative Domains

The quantum chromodynamics(QCD) coupling αs is the most important parameter for achieving precise QCD predictions. By using the well measured effective coupling α_(s)^(g)1)(Q) defined from the Bjorken sum rules as a basis, we suggest a novel self-consistency way to fix the αs at all scales: The QCD light-front holographic model is adopted for its infrared behavior, and the fixed-order p QCD prediction under the principle of maximum conformality(PMC) is used for its high-energy behavior. Using the PMC scheme-and-scale independent perturbative series,and by transforming it into the one under the physical V scheme, we observe that a precise αs running behavior in both the perturbative and nonperturbative domains with a smooth transition from small to large scales can be achieved.

Bound states in the continuum in metal-dielectric photonic crystal with a birefringent defect

By using the difference of the band structure for the TE and TM waves in the metal-dielectric photonic crystals beyond the light cone and the birefringence of the anisotropic crystal,a one-dimensional photonic system is constructed to realize the bound states in the continuum(BICs).In addition to the BICs arising from the polarization incompatibility,the Friedrich-Wintgen BICs are also achieved when the leaking TM wave is eliminated due to the destructive interference of its ordinary and extraordinary wave components in the anisotropic crystal.A modified scheme favorable for practical application is also proposed.This scheme for BICs may help to suppress the radiation loss in the metal-dielectric photonic crystal systems.

High-precision Measurements of Cosmic Curvature from Gravitational Wave and Cosmic Chronometer Observations

Although the spatial curvature has been measured with very high precision,it still suffers from the well-known cosmic curvature tension.In this paper,we use an improved method to determine the cosmic curvature,by using the simulated data of binary neutron star mergers observed by the second generation space-based DECi-hertz Interferometer Gravitational-wave Observatory(DECIGO).By applying the Hubble parameter observations of cosmic chronometers to the DECIGO standard sirens,we explore different possibilities of making measurements of the cosmic curvature referring to a distant past:one is to reconstruct the Hubble parameters through the Gaussian process without the influence of hypothetical models,and the other is deriving constraints onΩKin the framework of the non-flatΛcold dark matter model.It is shown that in the improved method DECIGO could provide a reliable and stringent constraint on the cosmic curvature(ΩK=-0.007±0.016),while we could only expect the zero cosmic curvature to be established at the precision ofΔΩK=0.11 in the second model-dependent method.Therefore,our results indicate that in the framework of methodology proposed in this paper,the increasing number of well-measured standard sirens in DECIGO could significantly reduce the bias of estimations for cosmic curvature.Such a constraint is also comparable to the precision of Planck 2018 results with the newest cosmic microwave background(CMB)observations(ΔΩK≈0.018),based on the concordanceΛCDM model.

Deep learning method for testing the cosmic distance duality relation

The cosmic distance duality relation(DDR)is constrained by a combination of type-Ⅰa supernovae(SNe la)and strong gravitational lensing(SGL)systems using the deep learning method.To make use of the full SGL data,we reconstruct the luminosity distance from SNeⅠa up to the highest redshift of SGL using deep learning,and then,this luminosity distance is compared with the angular diameter distance obtained from SGL.Considering the influence of the lens mass profile,we constrain the possible violation of the DDR in three lens mass models.The results show that.in the singular isothermal sphere and extended power-law models,the DDR is violated at a high confidence level,with the violation parameterη0=-0.193-0.019+0.021andη0=-0.247-0.013+0.014,respectively.In the power-law model,however,the DDR is verified within a 1σconfidence level,with the violation parameterη0=-0.014-0.045+0.053.Our results demonstrate that the constraints on the DDR strongly depend on the lens mass models.Given a specific lens mass model,the DDR can be constrained at a precision of O(10-2)using deep learning.

探索Bi_(2)SeO_(5)的高介电性能:从块体到双层和单层

Bi_(2)SeO_(5)是一种具有优异电绝缘性能的范德华(vdW)层状介电材料,引起了极大关注.然而,目前关于Bi_(2)SeO_(5)的研究主要停留在实验层面,仍然缺乏对其原子级薄膜的介电性能的相关理论认识.本文通过第一性原理计算确定了Bi_(2)SeO_(5)的介电性能,发现其块体、双层和单层均具有超高平均介电常数(εr>20).研究表明,单层Bi_(2)SeO_(5)与双层Bi_(2)O_(2)Se之间的导带和价带能量偏移量均大于1 eV,表明单层Bi_(2)SeO_(5)依然可作为原子薄Bi_(2)O_(2)Se的良好介电层.此外,不同于h-BN或其他2D vdW绝缘体,Bi_(2)SeO_(5)的εr由其离子部分主导,且随着厚度的减小几乎保持不变.计算发现,单层Bi_(2)SeO_(5)的等效氧化层厚度可薄至0.3 n m,且单层Bi_(2)SeO_(5)在拉伸或压缩应变达到6%时均能保持高介电常数,这极大地促进了它与各种二维半导体的集成.本工作证明单层Bi_(2)SeO_(5)可以作为高性能二维电子器件良好的封装和介电层.

Revisiting the top-quark pair production at future e^(+)e^(−)colliders

In this study,we reanalyze the top-quark pair production at next-to-next-to-leading order(NNLO)in quantum chromodynamics(QCD)at future e^(+)e^(−)colliders using the Principle of Maximum Conformality(PMC)method.The PMC renormalization scales inαs are determined by absorbing the non-conformalβterms by recursively using the Renormalization Group Equation(RGE).Unlike the conventional scale-setting method of fixing the scale at the center-of-mass energyμ_(r)=√s,the determined PMC scale Q_(⋆)is far smaller than the √sand increases with the √s,yielding the correct physical behavior for the top-quark pair production process.Moreover,the convergence of the pQCD series for the top-quark pair production is greatly improved owing to the elimination of the renormalon divergence.For a typical collision energy of √s=500 GeV,the PMC scale is Q_(⋆)=107 GeV;the QCD correction factor K for conventional results is K∼1+0.1244+0.0102+0.0012−0.0087−0.0011+0.0184−0.0086+0.0002+0.0061−0.0003,where the first error is caused by varying the scaleμr∈[√s/2,2√s]and the second error is from the top-quark massΔm_(t)=±0.7 GeV.After applying the PMC,the renormalization scale uncertainty is eliminated,and the QCD correction factor K is improved to K∼1+0.1507_(−0.0015)^(+0.0015)−0.0057_(−0.0000)^(+0.0001),where the error is from the top-quark massΔm_(t)=±0.7 GeV.The PMC improved predictions for the top-quark pair production are helpful for detailed studies of the properties of the top-quark at future e^(+)e^(−)colliders.

B_(c)→J/ψhelicity form factors and the B_(c)^(+)→J/ψ+(P,V,ℓ^(+)ν_(ℓ))decays

In this paper,we calculate the B_(c)→J/ψhelicity form factors(HFFs)up to twist-4 accuracy by using the light-cone sum rules(LCSR)approach.After extrapolating those HFFs to the physically allowable q^(2)region,we investigate the B_(c)^(+)-meson two-body decays and semi-leptonic decays B_(c)^(+)→J/ψ+(P,V,ℓ^(+)ν_(ℓ)),where P/V stand for light pseudoscalar and vector mesons,respectively.The branching fractions can be derived using the CKM matrix element and the B_(c)lifetime from the Particle Data Group,and we obtain B(B^(+)_(c)→J/ψπ^(+))=(0.136+0.002−0.002)%,B(B^(+)_(c)→J/ψK^(+))=(0.010+0.000−0.000)%,B(B^(+)_(c)→J/ψρ+)=(0.768+0.029−0.033)%,B(B^(+)_(c)→J/ψK^(∗+))=(0.043+0.001−0.001)%,B(B^(+)_(c)→J/ψ_(μ)+ν_(μ))=(2.802+0.526−0.675)%and B(B^(+)_(c)→J/ψτ^(+)ν_(τ))=(0.559+0.131−0.170)%.We then obtain R_(π^(+)/μ+ν_(μ))=0.048+0.009−0.012 and R_(K^(+)/π^(+))=0.075+0.005−0.005,which agree with the LHCb measured value within 1σ-error.We also obtain R_(J/ψ)=0.199+0.060−0.077,which like other theoretical predictions,is consistent with the LHCb measured value within 2σ-error.These imply that the HFFs under the LCSR approach are also applicable to the B+c meson two-body decays and semi-leptonic decays B+c→J/ψ+(P,V,ℓ^(+)ν_(ℓ)),and the HFFs obtained using LCSR in a new way implies that there may be new physics in the B_(c)→J/ψℓ^(+)ν_(ℓ)semi-leptonic decays.

Total decay width of H → gg using the infinite-order scale-setting approach based on intrinsic conformality

We conducted a detailed study on the properties of the total decay width of the Higgs decay channel H→gg up toα_(s)^(6)-order QCD corrections by using the newly suggested infinite-order scale-setting approach,which is based on both the principle of maximum conformality and intrinsic conformality.This approach is called PMC_(∞) By using the PMC_(∞)approach,we observed that the conventional renormalization scale ambiguity in perturbative QCD calculation is eliminated,and the residual scale dependence due to unknown higher-order terms can also be highly suppressed.We then obtained an accurate perturbative QCD prediction on the total decay width,e.g.,Г(H→gg)|PMC_(∞)=336.42_(-6.92)^(+7.01)keV,where the errors are squared averages of those from all the mentioned error sources.

Simulation of high-frequency gravitational wave detection using modulated Gaussian beam

This paper investigates the feasibility of using a Li-Baker detector based on a modulated Gaussian beam to detect gravitational waves in the GHz band.The first-order perturbation photon fluxes(PPF,signal of the detector)and the background photon fluxes(BPF,main noise of the detector),which vary with time,and the transverse distance are calculated.The results show that their propagation directions and energy densities are much different in some areas.Apart from BPF,we also consider two other important noises:diffraction noise and shot noise.In the simulation,it is found that the diffraction noise and shot noise are both lower than the signal level.Meanwhile,the main noise(BPF)can be eliminated when the receiving screen is located in certain special transverse areas where the BPF direction is opposite to that of PPF.Thus,the signal to noise ratio(SNR)obtained using our detection method can reach up to 320 in some transverse areas.These results are beneficial for the design of the Li-Baker detector.

Chiral edge state coupling theory of transport in quantum anomalous Hall insulators

The quantum anomalous Hall effect is characterized by a quantized Hall resistance with a vanishing longitudinal resistance.Many experiments reported the quantization of the Hall resistance,which is always accompanied by a non-vanishing longitudinal resistance that is several k?.Meanwhile,the non-vanishing longitudinal resistance exhibits a universal exponential decay with the increase in magnetic field.We propose that the coupling of chiral edge states,which has not been properly evaluated in the previous theories,can give rise to the non-vanishing longitudinal resistance.The coupling between the chiral edges states along the opposite boundaries can be assisted by magnetic domains or defects inside the sample bulk,which has been already identified in recent experiments.Our theory provides a potential mechanism to understand the experimental result in both magnetic topological insulator and moirésuperlattice systems.

Inferring redshift and energy distributions of fast radio bursts from the first CHIME/FRB catalog

We reconstruct the extragalactic dispersion measure-redshift(DM_(E)-z)relation from well-localized fast radio bursts(FRBs)using Bayesian inference.Then,the DM_(E)-z relation is used to infer the redshift and energy of the first CHIME/FRB catalog.We find that the distributions of the extragalactic dispersion measure and inferred redshift of the non-repeating CHIME/FRBs follow a cut-off power law but with a significant excess at the low-redshift range.We apply a set of criteria to exclude events that are susceptible to the selection effect,but the excess at low redshifts still exists in the remaining FRBs(which we call the gold sample).The cumulative distributions of fluence and energy for both the full sample and the gold sample do not follow the simple power law,but they can be well fitted by the bent power law.The underlying physical implications require further investigation.

Shadow thermodynamics of the Hayward-AdS black hole

In this paper,the phase structure of the Hayward-anti-de Sitter(AdS)black hole(BH)is studied using shadow formalism.It has been found that the shadow radius is a monotonic function of the horizon radius and can therefore play an equivalent role to the horizon radius in characterizing the thermodynamics of the Hayward-AdS BH.The thermodynamic phase transition(PT)of the Hayward-AdS BH is investigated with the shadow radius.It is shown that as the magnetic charge increases,the shadow radius becomes larger,while the coexistence temperature becomes lower.The thermal profile of the Hayward-AdS BH is established by combining the temperature diagram and the shadow cast diagram,which shows that for a fixed magnetic charge,the temperature of the Hayward-AdS BH increases with the pressure whereas the region of the thermal profile decreases with the pressure.In particular,the temperature of the Hayward-AdS BH follows an N-type change trend when it is smaller than the critical temperature.It implies that the BH shadow may be used to investigate the thermodynamics of the Hayward-AdS BH.

Consistency of Pantheon+supernovae with a large-scale isotropic universe

We investigate the possible anisotropy of the universe using data on the most up-to-date type Ia supernovae,i.e.,the Pantheon+compilation.We fit the full Pantheon+data with the dipole-modulated ΛCDM model and find that the data are well consistent with a null dipole.We further divide the full sample into several subsamples with different high-redshift cutoffs zc.It is shown that the dipole appears at the 2σ confidence level only if z_(c)≤0.1,and in this redshift region,the dipole is very stable,almost independent of the specific value of zc.For z_(c)=0.1,the dipole amplitude is D=1.0_(-0.4^(+0.4))×10^(-3),pointing toward(l,b)=(334.5°_(-21.6°)^(+25.7°),16.0°_(-16.8°)^(+27.1°)),which is approximately 65°away from the CMB dipole.This implies that the full Pantheon+sample is consistent with a large-scale isotropic universe,but the low-redshift anisotropy could not be purely explained by the peculiar motion of the local universe.