Microwave-enhanced laser-induced breakdown spectroscopy (ME-LIBS) is a promising analysis technique for trace element detection with the advantage of high signal intensity. However, the shot-to-shot repeatability of the ME-LIBS signal is relatively low, which affects the precision of the result and limits quantification performance. A cavity confinement microwave-enhanced laser-induced plasma (CC-ME-LIP) modulation method is proposed to improve the repeatability of the ME-LIBS signal. During the plasma evolution, cavity confinement provides an environment that regulates plasma around the microwave probe, controls plasma expansion, and minimizes interaction with the atmosphere. This behavior enhances the stability of the plasma morphology, leading to improved signal repeatability. In addition, confinement increases the energy transfer process within the plasma by the superimposition of two methods, resulting in a stronger signal intensity. The CC-ME-LIP modulation method is applied to the brass sample. The relative standard deviation (RSD) of the different copper and zinc lines has been reduced, along with an improvement of the intensity enhancement factor (IEF). For example, Cu 521.820 nm line RSD reduced from 29.11% (ME-LIBS) to 17.12% (CC-ME-LIBS) with an IEF of 1.08. The result demonstrated that the proposed approach significantly improves the repeatability of the ME-LIBS signal, thereby increasing the overall signal quality. To gain a deeper understanding, a detailed analysis of the mechanisms behind the increased signal intensity and improved repeatability was further investigated.
Two-dimensional (2D) transition-metal dichalcogenides (TMDs) materials have unique band structure as well as excellent electrical and optical properties, which exhibit great advantages in optoelectronic devices. Chemical vapor deposition (CVD), a method to realize the synthesis of large-scale 2D TMDs materials, will inevitably introduce defects in the growth process, thus decreasing the performance of 2D TMDs-based optoelectronic devices. In order to fundamentally address this issue, we proposed a method to gradually regulate the reaction concentration of precursor during growth. As a result, the suitable concentration of precursor can effectively enhance the probability of covalent binding of X−M (X: S, Se, etc.; M: Mo, W, etc.), thus suppressing the generation of vacancy defects. Furthermore, we explored sulfur vacancy (VS) on the performance of 2D molybdenum disulfide-based (MoS2-based) self-powered devices through constructing p-type silicon/MoS2 (p-Si/MoS2) based p–n heterojunction. The photodetector composed of optimized MoS2 nanosheets exhibited high responsivity (330.14 A·W−1), fast response speed (40 μs/133 μs), and excellent photovoltage stability. This method of regulating the low temperature region during CVD growth can realize the preparation of high-quality TMDs films and be applied in high-performance optoelectronic devices.
Topological flat bands have attracted significant interest across various branches of physics, where synthetic gauge fields are typically considered an essential prerequisite. Numerous mechanisms have been proposed for implementing these fields, including magnetic fields on electrons, differential optical paths for photons, and strain-induced effective magnetic fields, among others. In this work, we introduce a novel approach to generating synthetic gauge fields through quantum statistics and demonstrate their effectiveness in realizing anyonic topological flat bands. Notably, we discover that a pair of strongly interacting anyons can induce square-root topological flat bands within a lattice model that remains dispersive and topologically trivial for a single particle. To validate our theoretical predictions, we experimentally simulate the quantum statistics-induced topological flat bands and square-root topological boundary states by mapping the eigenstates of two anyons onto modes in electric circuits. Our findings not only open a new pathway for creating topological flat bands but also deepen our understanding of anyonic physics and the underlying principles of flat-band topology.
We study the topology and localization properties of a generalized Su−Schrieffer−Heeger (SSH) model with a quasi-periodic modulated hopping. It is found that the interplay of off-diagonal quasi-periodic modulations can induce topological Anderson insulator (TAI) phases and reentrant topological Anderson insulator (RTAI), and the topological phase boundaries can be uncovered by the divergence of the localization length of the zero-energy mode. In contrast to the conventional case that the TAI regime emerges in a finite range with the increase of disorder, the TAI and RTAI are robust against arbitrary modulation amplitude for our system. Furthermore, we find that the TAI and RTAI can induce the emergence of reentrant localization transitions. Such an interesting connection between the reentrant localization transition and the TAI/RTAI can be detected from the wave-packet dynamics in cold atom systems by adopting the technique of momentum-lattice engineering.
Despite extensive research, the achievement of tunable Chern numbers in quantum anomalous Hall (QAH) systems remains a challenge in the field of condensed matter physics. Here, we theoretically proposed that Ti2X2 (X = P, As, Sb, Bi) can realize tunable Chern numbers QAH effect by adjusting their magnetization orientations. In the case of Ti2P2 and Ti2As2, if the magnetization lies in the x−y plane, and all C2 symmetries are broken, a low-Chern-number phase with C = 1 will manifest. Conversely, if the magnetization is aligned to the z-axis, the systems enter a high-Chern number phase with C = 3. As for Ti2Sb2 and Ti2Bi2, by manipulating the in-plane magnetization orientation, these systems can periodically enter topological phases (C = ±1) over a 60° interval. Adjusting the magnetization orientation from +z to −z will result in the systems’ Chern number alternating between ±1. The non-trivial gap in monolayer Ti2X2 (X = P, As, Sb, Bi) can reach values of 23.4, 54.4, 60.8, and 88.2 meV, respectively. All of these values are close to the room-temperature energy scale. Furthermore, our research has revealed that the application of biaxial strain can effectively modify the magnetocrystalline anisotropic energy, which is advantageous in the manipulation of magnetization orientation. This work provides a family of large-gap QAH insulators with tunable Chern numbers, demonstrating promising prospects for future electronic applications.
Metagratings (MGs) have emerged as a promising platform for manipulating the anomalous propagation of electromagnetic waves. However, traditional methods for designing functional MG-based devices face significant challenges, including complex model structures, time-consuming optimization processes, and specific polarization requirements. In this work, we propose an inverse-design approach to engineer simple MG structures comprising periodic air grooves on a flat metal surface, which can control anomalous reflection without polarization limitations. Through rigorous analytical methods, we derive solutions that achieve perfect retroreflection and perfect specular reflection, thereby leading to functional control over the linearly-polarized electromagnetic waves. Such capabilities enable intriguing functionalities including polarization-dependent retroreflection and polarization-independent retroreflection, as confirmed through full-wave simulations. Our work offers a simple and effective method to control freely electromagnetic waves, with potential applications spanning wavefront engineering, polarization splitting, cloaking technologies, and remote sensing.
Quantum teleportation allows the transmission of quantum states over arbitrary distances and is an applied tool in quantum computation and communication. This paper theoretically addresses the feasibility of quantum teleportation based on a single semiconductor quantum dot influenced by pure dephasing through the biexciton cascade decay. We also investigate the idea of remote sensing in quantum teleportation affected by pure dephasing. In particular, we compare the quality of quantum teleportation in single- and two-qubit schemes and show that, within the present model, single-qubit quantum teleportation has a quantum advantage. Finally, to investigate the dynamics of the system, we introduce important witnesses of the non-Markovian dynamics of the system, so that our results may solve outstanding problems in the realization of faithful quantum teleportation over a long time.
Entanglement and quantum correlations between atoms are not usually considered key ingredients of the superradiant phase transition. Here we consider the Tavis−Cummings model, a solvable system of two-levels atoms, coupled with a single-mode quantized electromagnetic field. This system undergoes a superradiant phase transition, even in a finite-size framework, accompanied by a spontaneous symmetry breaking, and an infinite sequence of energy level crossings. We find approximated expressions for the ground state, its energy, and the position of the level crossings, valid in the limit of a very large number of photons with respect to that of the atoms. In that same limit, we find that the number of photons scales quadratically with the coupling strength, and linearly with the system size, providing a new insight into the superradiance phenomenon. Resorting to novel multipartite measures, we then demonstrate that this quantum phase transition is accompanied by a crossover in the quantum correlations and entanglement between the atoms (qubits). The latters therefore represent suited order parameters for this transition. Finally, we show that these properties of the quantum phase transition persist in the thermodynamic limit.
In this paper, we present a novel method for the complete analysis of maximally hyperentangled state of photon system in two degrees of freedom (DOFs), resorting to the auxiliary high-dimensional entanglement in the third DOF. This method not only can be used for complete hyperentangled Bell state analysis of two-photon system, but also can be suitable for complete hyperentangled Greenberger−Horne−Zeilinger (GHZ) state analysis of three-photon system, and can be extended to the complete N-photon hyperentangled GHZ state analysis. In our approach, the parity information of hyperentanglement is determined via the measurement on evolved auxiliary high-dimensional entanglement, and the relative phase information of hyperentanglement is determined via the projective measurement. Moreover, this approach can be accomplished by just using linear optics, and is significant for the investigation of photonic hyperentangled state analysis.
Based on new obtained analytical results, the main properties of photon echo quantum memory protocols are analysed and discussed together with recently achieved experimental results. The main attention is paid to studying the influence of spectral dispersion and nonlinear interaction of light pulses with resonant atoms. The distinctive features of the effect of spectral dispersion on the quantum storage of broadband signal pulses in the studied echo protocols are identified and discussed. Using photon echo area theorem, closed analytical solutions for echo protocols of quantum memory are obtained, describing the storage of weak and intense signal pulses, allowing us to find the conditions for the implementation of high efficiency in the echo protocols under strong nonlinear interaction of signal and control pulses with atoms. The key existing practical problems and the ways to solve them in realistic experimental conditions are outlined. We also briefly discuss the potential of using the considered photon echo quantum memory protocols in a quantum repeater.
Variational quantum algorithms have been widely demonstrated in both experimental and theoretical contexts to have extensive applications in quantum simulation, optimization, and machine learning. However, the exponential growth in the dimension of the Hilbert space results in the phenomenon of vanishing parameter gradients in the circuit as the number of qubits and circuit depth increase, known as the barren plateau phenomena. In recent years, research in non-equilibrium statistical physics has led to the discovery of the realization of many-body localization. As a type of floquet system, many-body localized floquet system has phase avoiding thermalization with an extensive parameter space coverage and has been experimentally demonstrated can produce time crystals. We applied this circuit to the variational quantum algorithms for the calculation of many-body ground states and studied the variance of gradient for parameter updates under this circuit. We found that this circuit structure can effectively avoid barren plateaus. We also analyzed the entropy growth, information scrambling, and optimizer dynamics of this circuit. Leveraging this characteristic, we designed a new type of variational ansatz, called the “many-body localization ansatz”. We applied it to solve quantum many-body ground states and examined its circuit properties. Our numerical results show that our ansatz significantly improved the variational quantum algorithm.
Wave-particle duality as a fundamental tenet of quantum mechanics is crucial for advancing comprehension of quantum theories and developing quantum technologies with practical applications. However, taking into account experimental impact factors to develop a feasible measurement for wave-like and particle-like properties of light fields is an ongoing challenge, and the non-classicality extraction and determination remains to be explored. In this work, feasibly measurable second-order photon correlations based on Hanbury Brown−Twiss and Hong−Ou−Mandel interferences are employed to analyze the evolution of wave−particle duality for various input states. The wave-particle dualities of chaotic, coherent and mixed classical states as functions of time delay and coherence time are investigated. The realistic impacts of background noise, detection efficiency, intensity ratio and phase differences on the wave−particle duality of non-classical (Fock and squeezed coherent) states are unveiled. In noisy backgrounds with low detection efficiencies, efficient enhancement and extraction of non-classicality and a continuous transition from classical to non-classical region are achieved in single photon state mixed with coherent state by adjusting the phase difference from 0 to
Using the integration within ordered products, we obtain the analytical density-operator evolution of the general quadratic state
In a recent paper [Jiang, et al., Science 370, 1447 (2020)], it was reported that zero reflection or Klein tunneling can be observed for normally incident quasiparticles upon a potential barrier constructed by two phononic crystals (PCs) with Dirac cone band structures. Here, we develop a first-principles approach for accurate computation of the reflection of quasiparticles by a potential step with two PCs at normal incidence. Strikingly, it is found that minimal reflection of quasiparticles (
Brilliance of the fourth-generation synchrotron radiation sources are increased in the order of magnitude, which further emphasizes the coherent applications. The zoom system of traditional optics can realize coherence regulation while achieving the target size of focus spots at designated position. This paper develops the design method of zoom system to fully exploit partially coherent fields. According to the first-order optics and imaging theory, the design method is reasonably simplified. The flux-optimization acceptance-angle ratio approximately linearly varies with the coherent fraction, which contributes to the slit-aperture determination. In order to validate the design method, wave-optics simulations are conducted in this paper.
We consider a dipolar spin-1 Bose gas with SU(3) spin−orbit coupling trapped in a two-dimensional toroidal trap. Due to the combined effects of SU(3) spin−orbit coupling, dipole−dipole interaction, and spin−exchange interaction, the system exhibits a rich variety of ground-state phases and topological defects, including modified stripe, azimuthal distributed petal and triangular lattice, double-quantum spin vortices, and so on. In particular, by studying the spin texture of such a system, it is found that the formation and transformation between meron and skyrmion topological spin textures can be realized by a choice of dipole−dipole interaction, SU(3) spin−orbit coupling, and spin−exchange interaction. We also give an experimental protocol to observe such novel states within current experimental capacity.
Magnetic vortices hold great promise for advanced information storage applications due to their quartet degenerate states and high topological stability. The key to their application lies on meticulous control of its polarity and chirality, which traditionally relies on magnetic fields, currents, and spin waves. However, the vortex core’s intrinsic precession under these stimuli hampers fast switching of the polarity and chirality. Here, we demonstrate a fast and precise control of polarity and chirality in magnetic vortices using combined femtosecond (fs) laser and tiny magnetic fields via micromagnetic simulations on Permalloy nanodisks. The fs laser pulse induces an ultrafast quench effect to establish the initial paramagnetic state, while the simultaneously applied magnetic fields precisely target the final vortex structure. Intriguingly, a 110 mT out-of-plane field and a 7 mT in-plane circular field are sufficient to realize precise control of the polarity and chirality on sub-nanosecond time scale, respectively, which are much lower than that of the previous work. Our approach guarantees fast and reliable switching of magnetic vortex polarity and chirality, paving the groundwork for a high-speed quaternary data storage and contributing a novel perspective to the fundamentals of spintronics.
