摘要：quantum secure direct communication(QSDC)attracts much attention for it can transmit secret messages directly without sharing a *** this article,we propose a one-step QSDC protocol,which only requires to distribute polarization-spatial-mode hyperentanglement for one *** this QSDC protocol,the eavesdropper cannot obtain any message,so that this protocol is unconditionally secure in *** protocol is a two-way quantum communication and has high capacity for it can transmit two bits of secret messages with one pair of *** entanglement fidelities of both polarization and spatial-mode degrees of freedom being 0.98,the maximal communication distance of this onestep QSDC can reach about 216 *** can also be used to generate the *** this regard,the key generation rate is estimated about 2.5 times of that in the entanglement-based QKD with the communication distance of 150 *** the help of future quantum repeaters,this QSDC protocol can provide unconditionally secure communication over arbitrarily long distance.

摘要：复杂的超导量子电路可以用来设计对噪声免疫的量子比特,但其复杂性可能会超出经典计算机所具备的模拟能力.在这种情况下,可以借助量子计算机来对其进行高效的模拟.在这项工作中,作者展示了在基于transmon比特的量子计算机上,利用变分量子算法模拟一种超导量子电路,并且基于此设计了一种新的量子比特“Plasmonium”,它工作在等离子体跃迁区域.文中展示的Plasmonium量子比特展示出了较高的两比特门保真度99.58(3)%.相比于transmon比特,它具有更小的物理尺寸和更大的非谐性.这些特征使得Plasmonium可以成为制造多比特量子处理器强有力的候选者.这项研究结果证实了利用量子计算机辅助设计更先进的量子处理器的可能性.

摘要：Controlling the polar order in ferroelectric materials may enrich the diversity of their property and functionality,offering new opportunities for the design of novel electronic and optoelectronic *** this paper,we report a planar multi-state memory device built upon a twodimensional(2D)van der Waals layered ferroelectric material,2Hα-In_(2)Se_(3).Three(high,median and low)resistance states are demonstrated to be interconvertible in this device with a fast switching speed,excellent endurance and retention performances via the modulation of the polar order of the ferroelectricα-In_(2)Se_(3) layers under an in-plane electric ***,reversible switching between the median-resistance state and the low-resistance state can be achieved by an ultralow electric field of 1-2 orders of magnitude smaller than the reported values in other 2D ferroelectric materialbased memory ***,the three different polar order states are discovered to exhibit distinctive *** results demonstrate great potentials ofα-In_(2)Se_(3)in nonvolatile high-density memory and advanced optoelectronic device applications.

摘要：由非平衡驱动的热传导通过物理接触传递内部的热能.描述热传导的数学方程是一个典型的偏微分方程.它广泛存在于各种工程问题中,例如粒子扩散、航天器设计和稀释制冷机运行.本文提出了一种显著优于经典算法的热传导量子算法,并在量子硬件上演示了热传导过程.作者通过一个辅助量子比特构造的对称系统来表示原始热传导系统,使得量子线路的复杂度减少到离散格点数量的对数多项式量级.与现有的基于Harrow-Hassidim-Lloyd的线性方程算法相比,本文的方法直接演化线性过程,不进行相位估计,避免相位估计涉及复杂的量子门操作和较大的输出误差,便于在目前的量子硬件实现,显示了该算法是实验友好特性.并且,作者在核自旋量子处理器上实现了两端恒温和绝热条件的一维热传导过程,温度的时空分布与理论预言很好的吻合.该算法可以自然地应用于可归约为热方程的物理过程.

摘要：The recen tly cons true ted cryogenic cylindrical ion trap velocity map imaging spectrometer(CIT-VMI)has been upgraded for coincidence imaging of both ionic and neutral photofragments from photodissociation of ionic *** prepared ions are cooled down in a homemade cryogenic cylindrical ion trap and then extracted for photodissociation *** th the newly designed elec trie fields for extraction and acceleration,the ion beam can be accelerated to more than 4500 eV,which is necessary for velocity imaging of the neutral photofragments by using the position-sensitive imaging detect *** setup has been tested by the 355 nm pho todissocia tion dynamics of the argon dimer cat ion(Ar2+).From the recorded experimen tal images of both neu tral Ar and ionic Ar+fragments,we interpret velocity resolutions of△v/vu4.6%for neutral fragments,and△v/vul.5%for ionic fragments,respectively.

摘要：We study the expansion behaviors of a Fermionic superfluid in a cigar-shaped optical dipole trap for the whole BEC-BCS crossover and various *** low temperature(0:06(1)T_F),the atom cloud undergoes an anisotropic hydrodynamic expansion over 30 ms,which behaves like oscillation in the horizontal *** analyzing the expansion dynamics according to the superfluid hydrodynamic equation,the effective polytropic index y of Equation-of-State(EoS)of Fermionic superfluid is *** y values show a non-monotonic behavior over the BEC-BCS crossover,and have a good agreement with the theoretical results in the unitarity and BEC *** normalized quasi-frequencies of the oscillatory expansion are measured,which drop significantly from the BEC side to the BCS side and reach a minimum value of 1.73 around 1/k_Fa=-0:*** work improves the understanding of the dynamic properties of strongly interacting Fermi gas.

摘要：Photocatalytic N_(2)xation has attracted substantial attention in recent years,as it represents a green and sustainable devel-opment route toward effciently convert-ing N_(2)to NH_(3)for industrial *** to rationally design catalysts in this regard remains a *** we pro-pose a strategy that uses plasmonic hot electrons in the highly doped TiO_(2)to ac-tivate the inert N_(2)*** synthesized semiconductor catalyst Mo-doped TiO_(2)shows a NH_(3)production effciency as high as 134μmol·g^(-1)·h^(-1)under ambient conditions,which is comparable to that achieved by the conventional plasmonic gold *** means of ultra-fast spectroscopy we reveal that the plasmonic hot electrons in the system are responsible for the activation of N_(2)molecules,enabling improvement the catalytic activity of TiO_(2).This work opens a new avenue toward semiconductor plasmon-based photocatalytic N_(2)xation.

摘要：We constructed two types of copper-doped metal-organic framework(MOF),i.e.,Cu@UiO-66-NH2 and *** the former,Cu2+ions are impregnated in the pore space of the amine-functionalized,Zr-based UiO-66-NH2;while in the latter,Cu^2+ions are incorporated to form a bimetal-center MOF,with Zr^4+being partially replaced by Cu2+in the Zr-O *** spectroscopy revealed that the photoinduced relaxation kinetics associated with the ligand-to-cluster charge-transfer state is promoted for both Cudoped MOFs relative to undoped one,but in a sequence of Cu-UiO-66-NH2>Cu@UiO-66-NH2>*** a sequence turned to be in line with the trend observed in the visible-light photocatalytic hydrogen evolution activity tests on the three *** findings highlighted the subtle effect of copper-doping location in this Zr-based MOF system,further suggesting that rational engineering of the specific metal-doping location in alike MOF systems to promote the photoinduced charge separation and hence suppress the detrimental charge recombination therein is beneficial for achieving improved performances in MOF-based photocatalysis.

摘要：电子结构和电导率是析氧反应活性的重要描述符,它们可以通过掺杂来调节.鉴于金属掺杂通常会减少电催化剂的活性位点数量,本工作探究了阴离子掺杂对尖晶石钴酸锌(ZCO)电子结构及其析氧活性的影响.与三价钴为主的ZCO相比,用电负性较低的硫取代氧会提高低自旋态(t_(2g)-^(6)e_(g)^(1))二价钴的占比,其析氧活性要高于低自旋态的三价钴(t_(2g)-^(6)e_(g)^(0)).掺硫钴酸锌(ZCO-S)中钴离子和阴离子之间的电子密度的再分布导致了二价钴的增多,而且钴和硫离子间的强共价作用也会加速电荷迁移.ZCO-S在1.65伏(相对于可逆氢电极)下的比活性比原始ZCO高11倍.相反,掺入具有较高电负性和价态的氟(F)并不能有效地改善电子结构,最终导致材料析氧活性的降低.本工作建立了所掺阴离子的电负性与钴酸锌本征析氧活性之间的联系,并提供了一种通过掺杂不同电负性的阴离子来调控尖晶石氧化物的电子结构的简单有效的方法,这为合理设计高性能尖晶石电催化剂提供了新途径.

摘要：Though several theoretical models have been proposed to design electronic flat-bands, the definite experimental realization in two-dimensional atomic crystal is still lacking. Here we propose a novel and realistic flat-band model based on threefold degenerate p-orbitals in two-dimensional ionic materials. Our theoretical analysis and first-principles calculations show that the proposed flat-band can be realized in 1 T layered materials of alkali-metal chalogenides and metal-carbon group compounds. Some of the former are theoretically predicted to be stable as layered materials(e.g., K2 S), and some of the latter have been experimentally fabricated in previous works(e.g., Gd2 CCl2). More interestingly, the flat-band is partially filled in the heterostructure of a K2 S monolayer and graphene layers. The spin polarized nearly flatband can be realized in the ferromagnetic state of a Gd2 CCl2 monolayer, which has been fabricated in experiments. Our theoretical model together with the material predictions provide a realistic platform for the study of flat-bands and related exotic quantum phases.