Manipulation of High-Fidelity Sidebands under Large Detuning by Floquet Technology:Application to Multi-Mode Cooling

The Floquet technology,a powerful way to manipulate quantum states,is employed to drive sidebands transition under large detuning.Our results demonstrate that high fidelities over 99%can be achieved through optimizing suitable modulation frequencies under large detuning.We observe high-fidelity transitions within a high bandwidth by utilizing a single modulation frequency and reveal that this capability is due to the emergence of a flat-band structure in the bandwidth range.The key finding of high-fidelity sideband manipulation under large detuning is experimentally confirmed in nuclear magnetic resonance platform.Finally,we propose a new parallel sideband cooling scheme that enables simultaneous cooling of multiple motional modes.This approach improves the cooling rate compared to conventional schemes with fixed laser frequency and power,and eliminates the need for mode-specific addressing.Our Floquet parallel scheme is applicable to any harmonic oscillator system and is not limited by bandwidth in theory.

Valence Bands Convergence in p-Type CoSb_(3) through Electronegative Fluorine Filling

Band convergence is considered to be a strategy with clear benefits for thermoelectric performance,generally favoring the co-optimization of conductivity and Seebeck coefficients,and the conventional means include elemental filling to regulate the band.However,the influence of the most electronegative fluorine on the CoSb_(3) band remains unclear.We carry out density-functional-theory calculations and show that the valence band maximum gradually shifts downward with the increase of fluorine filling,lastly the valence band maximum converges to the highly degenerated secondary valence bands in fluorine-filled skutterudites.

Highly Active Interfacial Sites in SFT-SnO_(2) Heterojunction Electrolyte for Enhanced Fuel Cell Performance via Engineered Energy Bands:Envisioned Theoretically and Experimentally

Extending the ionic conductivity is the pre-requisite of electrolytes in fuel cell technology for high-electrochemical performance.In this regard,the introduction of semiconductor-oxide materials and the approach of heterostructure formation by modulating energy bands to enhance ionic conduction acting as an electrolyte in fuel cell-device.Semiconductor(n-type;SnO_(2))plays a key role by introducing into p-type SrFe_(0.2)Ti_(0.8)O_(3-δ)(SFT)semiconductor perovskite materials to construct p-n heterojunction for high ionic conductivity.Therefore,two different composites of SFT and SnO_(2)are constructed by gluing p-and n-type SFT-SnO_(2),where the optimal composition of SFT-SnO_(2)(6∶4)heterostructure electrolyte-based fuel cell achieved excellent ionic conductivity 0.24 S cm^(-1)with power-output of 1004 mW cm^(-2)and high OCV 1.12 V at a low operational temperature of 500℃.The high power-output and significant ionic conductivity with durable operation of 54 h are accredited to SFT-SnO_(2)heterojunction formation including interfacial conduction assisted by a built-in electric field in fuel cell device.Moreover,the fuel conversion efficiency and considerable Faradaic efficiency reveal the compatibility of SFT-SnO_(2)heterostructure electrolyte and ruled-out short-circuiting issue.Further,the first principle calculation provides sufficient information on structure optimization and energy-band structure modulation of SFT-SnO_(2).This strategy will provide new insight into semiconductor-based fuel cell technology to design novel electrolytes.

Observation of parabolic electron bands on superconductor LaRu_(2)As_(2)

Ru-based superconductor LaRu_(2)As_(2) has been discovered exhibiting the highest critical temperature of ~ 7.8 K among iron-free transition metal pnictides with the ThCr_(2)Si_(2)-type crystal structure. However, microscopic research on this novel superconducting material is still lacking. Here, we utilize scanning tunneling microscopy/spectroscopy to uncover the superconductivity and surface structure of LaRu_(2)As_(2). Two distinct terminating surfaces are identified on the cleaved crystals, namely, the As surface and the La surface. Atomic missing line defects are observed on the La surface. Both surfaces exhibit a superconducting gap of ~ 1.0 me V. By employing quasiparticle interference techniques, we observe standing wave patterns near the line defects on the La atomic plane. These patterns are attributed to quasiparticle scattering from two electron type parabolic bands.

Extracting Feature Bands for Damaged Rice Leaves by Planthoppers Using Multi-spectral Imaging Technology

[Objective] The aim of this study was to extract effective feature bands of damaged rice leaves by planthoppers to make identification and classification rapidly from great amounts of imaging spectral data. [Method] The experiment, using multi-spectral imaging system, acquired the multi-spectral images of damaged rice leaves from band 400 to 720 nm by interval of 5 nm. [Result] According to the principle of band index, it was calculated that the bands at 515, 510, 710, 555, 630, 535, 505, 530 and 595 nm were having high band index value with rich information and little correlation. Furthermore, the experiment used two classification methods and calcu-lated the classification accuracy higher than 90.00% for feature bands and ful bands of damaged rice leaves by planthoppers respectively. [Conclusion] It can be con-cluded that these bands can be considered as effective feature bands to identify damaged rice leaves by planthoppers quickly from a large scale of crops.

Systematic Behaviors of Signature Inversion in πh_(9/2) ■vi_(13/2) Bands in A~170 Mass Region

Low-spin signature inversion in theπh9/2■vi_(13/2)band was reported for the first time by Bark et al.~[1]in^(162,164)Tm and^(174)Ta in 1997.Since then,this inversion phenomenon has been found in several neighboring odd-odd nuclei.During the past few years,we have made great efforts to investigate the band structures in odd-odd nuclei in this mass rgion,leading to observation of signature invesion in^(170)Ta,^(172)Re,^(176~280)Ir and ^(182)Au,respectively.

Deformation, Phase Transformation and Recrystallization in the Shear Bands Induced by High-Strain Rate Loading in Titanium and Its Alloys

α-titanium and its alloys with a dual-phase structure （α＋β） were deformed dynamically under strain rate of about 10^4 s^-1. The formation and microstructural evolution of the localized shear bands were characterized by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The results reveal that both the strain and strain rate should be considered simultaneously as the mechanical conditions for shear band formation, and twinning is an important mode of deformation. Both experimental and calculation show that the materials within the bands underwent a superhigh strain rate （9×10^5 S^-1） deformation, which is two magnitudes of that of average strain rate required for shear band formation; the dislocations in the bands can be constricted and developed into cell structures; the phase transformation from α to α2 within the bands was observed, and the transformation products （α2） had a certain crystallographic orientation relationship with their parent; the equiaxed grains with an average size of 10 μm in diameter observed within the bands are proposed to be the results of recrystallization.

Dynamic Mechanical Behavior and Adiabatic Shear Bands of Ultrafine Grained Pure Zirconium

Dynamic compression tests were carried out to investigate dynamic mechanical behavior and adiabatic shear bands in ultrafine grained(UFG)pure zirconium prepared by equal channel angular pressing(ECAP)and rotary swaying.The cylindrical specimens were deformed dynamically on the split Hopkinson pressure bar(SHPB)at different strain rates of 800 to 4000s^-1 at room temperature.The temperature distribution of the shear bands was estimated on the basis of temperature rise of uniform plastic deformation stage and thermal diffusion effect.The results show that the true stress-true strain curves of UFG pure zirconium are concave upward trend of strain in range of 0.02-0.16 due to the effects of strain hardening,strain rate hardening and thermal softening.The formation of the adiabatic shear bands is the main reason of UFG pure zirconium failure.A large number of micro-voids are observed in the adiabatic shear bands,and the macroscopic cracks develop from the micro-voids coalescence.The fracture surface of UFG pure zirconium exhibits quasi cleavage fracture with the characteristic features of shear dimples and river pattern.The highest temperature within the shear bands of UFG pure zirconium is about 592 K.

The Interacting Boson Model for Anomalous Rotational Bands

The interacting boson model for anomalous rotational bands is proposed. In the rotational SU(3) limit,an asymptotic limit is discussed. Within the framework of the model several analytic relations for energies and electro-magnetic transition rates are derived.

Floquet bands and photon-induced topological edge states of graphene nanoribbons

Floquet theorem is widely used in the light-driven systems. But many 2 D-materials models under the radiation are investigated with the high-frequency approximation, which may not be suitable for the practical experiment. In this work,we employ the non-perturbative Floquet method to strictly investigate the photo-induced topological phase transitions and edge states properties of graphene nanoribbons under the light irradiation of different frequencies(including both low and high frequencies). By analyzing the Floquet energy bands of ribbon and bulk graphene, we find the cause of the phase transitions and its relation with edge states. Besides, we also find the size effect of the graphene nanoribbon on the band gap and edge states in the presence of the light.

Microscopic Mechanism of the Odd-Even Difference in Moments of Inertia of Superdeformed Bands

The large odd-even difference in moments of inertia between the SD bands l95Tl(l,2)and l96Pb(l)is investigated by the particle-number conserving method,in which the blocking effect on pairing is taken into account strictly.Theωvariation of J(2)for the three SD bands are reproduced quite well and the underlying microscopic mechanism is demonstrated clearly.Calculations show that the blocking of the proton[642]5/2 intruder orbital and the excitation of[651]1/2 intruder orbital play crucial roles for the odd-even difference in J(2)’s.

Nonlinear Generation of Perfect Vector Beams in Ultraviolet Wavebands

Perfect vector beams are a class of special vector beams with invariant radius and intensity profiles under changing topological charges.However,with the limitation of current devices,the generation of these vector beams is limited in the visible and infrared wavebands.Herein,we generate perfect vector beams in the ultraviolet region assisted by nonlinear frequency conversion.Experimental and simulation results show that the radius of the generated ultraviolet perfect vector beams remains invariant and is thus independent of the topological charge.Furthermore,we measure the power of the generated ultraviolet perfect vector beams with the change of their topological charges.This study provides an alternative approach to generating perfect vector beams for ultraviolet wavebands and may promote their application to optical trapping and optical communication.

Shear bands of as-cast and semi-solid Ti_(48)Zr_(27)Cu_(6)Nb_(5)Be_(14)bulk metallic glass matrix composites

The as-cast Ti_(48)Zr_(27)Cu_(6)Nb_(5)Be_(14)bulk metallic glass matrix composites(BMGMCs)were fabricated using a copper mold suction casting method.Then,the semi-solid BMGMC samples were obtained following an isothermal treatment(heating at 900°C for 10 min,then cooling with water).The microstructure and compression property were investigated by scanning electronic microscopy(SEM)and universal mechanical tester.As a result of the isothermal treatment,the crystal shapes change from fine,granular,and dendritic to spherical or vermicular,and the average crystal size of the as-cast and semi-solid samples is 2.2μm and 18.1μm,respectively.The plasticity increases from 5.31%in the as-cast to 10.23%in the semi-solid samples,with an increase of 92.66%.The shear bands from different areas of the side surfaces of as-cast and semisolid compression fracture samples were observed.The characteristic changes of multiplicity,bend,branch and intersection of shear bands in different areas indicate that the deformation of as-cast and semi-solid samples is non-uniform during compression.It is found that poor plasticity of the as-cast samples or good plasticity of the semi-solid samples are reflected by characteristics of the shear bands.The semi-solid isothermal treatment improves the plasticity by forming large crystals which can block the expansion of shear bands and promote the multiplicity of shear bands.

Prediction of shear bands in sand based on granular flow model and two-phase equilibrium

In contrast to the traditional interpretation of shear bands in sand as a bifurcation problem in continuum mechanics,shear bands in sand are considered as high-strain phase(plastic phase) of sand and the materials outside the bands are still in low-strain phase(elastic phase),namely,the two phases of sand can coexist under certain condition.As a one-dimensional example,the results show that,for materials with strain-softening behavior,the two-phase solution is a stable branch of solutions,but the method to find two-phase solutions is very different from the one for bifurcation analysis.The theory of multi-phase equilibrium and the slow plastic flow model are applied to predict the formation and patterns of shear bands in sand specimens,discontinuity of deformation gradient and stress across interfaces between shear bands and other regions is considered,the continuity of displacements and traction across interfaces is imposed,and the Maxwell relation is satisfied.The governing equations are deduced.The critical stress for the formation of a shear band,both the stresses and strains inside the band and outside the band,and the inclination angle of the band can all be predicted.The predicted results are consistent with experimental measurements.

Improvement of memory characteristics by employing a charge trapping layer with combining bent and flat energy bands

Designed ZrxSi1-xO2 films with combining bent and flat energy bands are employed as a charge trapping layer for memory capacitors.Compared to a single bent energy band,the bandgap structure with combining bent and flat energy bands exhibits larger memory window,faster program/erase speed,lower charge loss even at 200℃ for 104s,and wider temperature insensitive regions.The tunneling thickness together with electron recaptured efficiency in the trapping layer,and the balance of two competing electron loss mechanisms in the bent and flat energy band regions collectively contribute to the improved memory characteristics.Therefore,the proposed ZrxSi1-xO2 with combining bent and flat energy bands should be a promising candidate for future nonvolatile memory applications,taking into consideration of the trade-off between the operation speed and retention characteristics.

Surface State Bands in Superconducting(PtxIr1-x)Te2

Angle-resolved photoemission spectroscopy is performed to study the bulk and surface electronic structures of non- superconducting IrTe2 and superconducting Pto.oblro.95 Te2. In addition to the bulk electronic bands predicted by the local density approximation calculations, we observe two Dirac cone-like bands at the Brillouin zone center, which are non-dispersive along kz, suggesting that the extra bands are surface state bands. As the experimental results are well consistent with the ab initio calculations of surface states, the parity analysis proves that these surface state bands are topologically trivial and thus exclude （PtxIr1-x）Te2 as a possible topological superconductor candidate.

Unidentified Infrared Discrete Emission Bands

Unidentified Infrared emission bands (UIBs) are infrared discrete emissions from circumstellar regions, interstellar media (ISM), star-forming regions, and extragalactic objects for which the identity of the emitting materials is unknown. The main infrared features occur around peaks at 3.3, 6.2, 7.7, 8.6, 11.2, and 12.7 μm with the photon’s rest energy at the peaks 0.376, 0.200, 0.161, 0.144, 0.111, and 0.098 eV, respectively. The UIB emission phenomenon has been studied for about forty five years. The prevailing hypothesis is that the materials responsible for UIB are polycyclic aromatic hydrocarbon (PAH) molecules. PAHs are thought to be one of the main forms in which carbon exists in space. And yet, not a single member of this group of compounds had been identified in space definitively until now [1]. In frames of Hypersphere World-Universe Model (WUM), we introduced Dark Matter (DM) particles, named DIONs, with the rest energy 0.199 eV and an energy density of 68.8% of the total energy density of the World. DIONs compose Outer shells of DM Supercluster’s Cores—the main objects of the World [2]. In this paper, we give an explanation of UIB emission based on the self-annihilation of DM particles DIONs and biDIONs (DIONs pairs) with a rest energy about 0.38 eV that depends on the binding energy. To the best of our knowledge, WUM is the only cosmological model in existence that is consistent with UIB emission phenomenon.

Machine learning of theΓ-point gap and flat bands of twisted bilayer graphene at arbitrary angles

The novel electronic properties of bilayer graphene can be fine-tuned via twisting,which may induce flat bands around the Fermi level with nontrivial topology.In general,the band structure of such twisted bilayer graphene(TBG)can be theoretically obtained by using first-principles calculations,tight-binding method,or continuum model,which are either computationally demanding or parameters dependent.In this work,by using the sure independence screening sparsifying operator method,we propose a physically interpretable three-dimensional(3D)descriptor which can be utilized to readily obtain theΓ-point gap of TBG at arbitrary twist angles and different interlayer spacings.The strong predictive power of the descriptor is demonstrated by a high Pearson coefficient of 99%for both the training and testing data.To go further,we adopt the neural network algorithm to accurately probe the flat bands of TBG at various twist angles,which can accelerate the study of strong correlation physics associated with such a fundamental characteristic,especially for those systems with a larger number of atoms in the unit cell.

Erratum to“Floquet bands and photon-induced topological edge states of graphene nanoribbons”

Figures 2(a)and 2(b)in our original paper[1] should be corrected by the following ones.In Figs.2(a)and 2(b),in the region of hω0>5.96γ0(phase A),the Chern number should be corrected to 1,as indicated in the paper and Table 1.

Description of Rotation Bands in ^(157,158)Er at Ultrahigh Spin

Properties of the four rotation bands, ^157Er（1,2） and ^15SEr（1,2）, at ultrahigh spin are investigated within the supersymmetry scheme including many-body interactions and possessing the SO（5） （or SU（5）） symmetry on the rotational symmetry. Quantitatively good results of the 7-ray energies and the dynamical moments of inertia in the rotation bands in ^157 Er and ^158 Er at ultrahigh spin are obtained. We theoretically predict that the competition between the anti-pairing and pairing effects may exist in ^157 Er（1,2） and ^158Et（2） bands states. In ^158Er（1） band state, the favourepairing effects may exist and the SO（5） （or SU（5）） symmetry play a dominant role. There may be sphere coexisting with headecupole deformed in ^158Et（1） rotation band state.