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Quantum phase transition modulation in an atomtronic Mott switch
摘要： Mott insulators provide stable quantum states and long coherence times due to small number fluctuations, making them good candidates for quantum memory and atomic circuits. We propose a proof-of-principle for a 1D Mott switch using an ultracold Bose gas and optical lattice. With time-evolving block decimation simulations—efficient matrix product state methods—we design a means for transient parameter characterization via a local excitation for ease of engineering into more complex atomtronics. We perform the switch operation by tuning the intensity of the optical lattice, and thus the interaction strength through a conductance transition due to the confined modifications of the 'wedding cake' Mott structure. We demonstrate the time-dependence of Fock state transmission and fidelity of the excitation as a means of tuning up the device in a double well and as a measure of noise performance. Two-point correlations via the g(2) measure provide additional information regarding superfluid fragments on the Mott insulating background due to the confinement of the potential.
关键词： quantum gas,atomtronic switch,optical lattice,atomtronics,quantum phase transition,matrix product states,Mott insulator
更新于2025-09-23 15:23:52
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Lateral interfaces of transition metal dichalcogenides: A stable tunable one-dimensional physics platform
摘要： We study in-plane lateral heterostructures of commensurate transition-metal dichalcogenides, such as MoS2-WS2 and MoSe2-WSe2, and find interfacial and edge states that are highly localized to these regions of the heterostructure. These are one-dimensional (1D) in nature, lying within the band gap of the bulk structure and exhibiting complex orbital and spin structure. We describe such heteroribbons with a three-orbital tight-binding model that uses first principles and experimental parameters as input, allowing us to model realistic systems. Analytical modeling for the 1D interfacial bands results in long-range hoppings due to the hybridization along the interface, with strong spin-orbit couplings. We further explore the Ruderman-Kittel-Kasuya-Yosida indirect interaction between magnetic impurities located at the interface. The unusual features of the interface states result in effective long-range exchange noncollinear interactions between impurities. These results suggest that transition-metal dichalcogenide interfaces could serve as stable, tunable 1D platform with unique properties for possible use in exploring Majorana fermions, plasma excitations, and spintronics applications.
关键词： spin-orbit coupling,interface states,transition metal dichalcogenides,RKKY interaction,tight-binding model,lateral heterostructures
更新于2025-09-23 15:23:52
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Classification of flat bands according to the band-crossing singularity of Bloch wave functions
摘要： We show that ?at bands can be categorized into two distinct classes, that is, singular and nonsingular ?at bands, by exploiting the singular behavior of their Bloch wave functions in momentum space. In the case of a singular ?at band, its Bloch wave function possesses immovable discontinuities generated by the band-crossing with other bands, and thus the vector bundle associated with the ?at band cannot be de?ned. This singularity precludes the compact localized states from forming a complete set spanning the ?at band. Once the degeneracy at the band crossing point is lifted, the singular ?at band becomes dispersive and can acquire a ?nite Chern number in general, suggesting a new route for obtaining a nearly ?at Chern band. On the other hand, the Bloch wave function of a nonsingular ?at band has no singularity, and thus forms a vector bundle. A nonsingular ?at band can be completely isolated from other bands while preserving the perfect ?atness. All one-dimensional ?at bands belong to the nonsingular class. We show that a singular ?at band displays a novel bulk-boundary correspondence such that the presence of the robust boundary mode is guaranteed by the singularity of the Bloch wave function. Moreover, we develop a general scheme to construct a ?at band model Hamiltonian in which one can freely design its singular or nonsingular nature. Finally, we propose a general formula for the compact localized state spanning the ?at band, which can be easily implemented in numerics and offer a basis set useful in analyzing correlation effects in ?at bands.
关键词： Chern number,singular band touching,flat bands,nonsingular band touching,bulk-boundary correspondence,compact localized states,Bloch wave functions
更新于2025-09-23 15:23:52
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Supersymmetric Polarization Anomaly in Photonic Discrete-Time Quantum Walks
摘要： Quantum anomalies lead to finite expectation values that defy the apparent symmetries of a system. These anomalies are at the heart of topological effects in electronic, photonic, and atomic systems, where they result in a unique response to external fields but generally escape a more direct observation. Here, we implement an optical-network realization of a discrete-time quantum walk, where such an anomaly can be observed directly in the unique circular polarization of a topological midgap state. We base the system on a single-step protocol overcoming the experimental infeasibility of earlier multistep protocols. The evolution combines a chiral symmetry with a previously unexplored unitary version of supersymmetry. Having experimental access to the position and the coin state of the walker, we perform a full polarization tomography and provide evidence for the predicted anomaly of the midgap states. This approach opens the prospect to dynamically distill topological states for quantum information applications.
关键词： quantum anomalies,supersymmetry,polarization,discrete-time quantum walks,topological states
更新于2025-09-23 15:23:52
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Electronic and optical properties of double perovskite oxide Pb2ScMO6 (M = Ta, Sb) using a first principles approach
摘要： In this study, the electronic and optical properties of the double perovskite (DP) oxides Pb2ScMO6 (M = Sb, Ta) were systematically investigated using the full-potential linearized augmented plane wave model. Calculations were performed using both the generalized gradient approximation and modified Becke–Johnson potentials. The results showed that the O-atom is responsible for the maxima in the density of states (DOS) in the valence band, whereas the Sc-atom contributes to the maximum DOS in the conduction band. The dielectric constants, absorption coefficients, and reflectivity were also calculated for these systems. The results indicated the presence of wide band gaps in both of these DPs, thereby indicating their insulating semiconducting nature.
关键词： photon energy,energy,dielectric,double perovskite,density of states,band gap
更新于2025-09-23 15:23:52
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Polymorphic impedance matching technique for MEMS phase shifter
摘要： The amplitude and phase consistency control level is an important factor affecting the performance of phased array antenna. MEMS phase shifter has important application potential in phased array antenna, but the current MEMS phase shifter device has poor amplitude and phase consistency, making it difficult to integrate directly in phased array antenna system. In this paper, a novel multi-states matching technology for MEMS phase shifter is proposed to overcome the above-mentioned difficulty. To control amplitude fluctuation and phase shift error of phase shifter in the using process, we proposed a general network design method focusing on the given polymorphic S parameter matrix of MEMS phase shifter based on the theory of microwave network. The key of the method is as following: with the help of the mature microwave network synthesis method and the particle swarm optimization algorithm combined by matching circuit parameter optimization, obtain actual S parameter matrixes of two polymorphic matching networks for the corresponding MEMS phase shifter, so as to enhance the amplitude and phase consistency integrated application. The simulation results verify the feasibility of the method, and so that we form a technical way to improve the consistency of amplitude and phase of MEMS phase shifter system through polymorphic matching network, which has important theoretical and practical value.
关键词： multi-states,MEMS phase shifter,matching technology
更新于2025-09-23 15:23:52
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Critical impact of gate dielectric interfaces on the trap states and cumulative charge of high-performance organic thin field transistors
摘要： In the operation of OFETs, the electrical properties are strongly dependent on the merits of the constituting layers and the formed interfaces. Here we study the trap states variations at the interface between the organic semiconductor pentacene and polymer insulators. With ZrO2 dielectric modified by polymers and find a 10 × decrease in the density of trap states at the semiconductor/insulator interface, bring about the charge carrier mobility increase from 0.058 cm2/Vs to 0.335 cm2/Vs. In addition, when compare to the thicker films at the same applied gate voltage, the thinner film would lead to enhanced coupling capability and more charges cumulative cumulated at the channel region, which is pivotal for optimizing the performance of OFETs. The results prove that the property of the insulator layer could impact largely on the device performance.
关键词： Organic thin film transistor,Cumulative charge,Insulator/semiconductor interface,Trap states
更新于2025-09-23 15:23:52
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Photoinduced triboelectric polarity reversal and enhancement of a new metal/semiconductor triboelectric nanogenerator
摘要： We reported a novel metal/semiconductor triboelectric nanogenerator (TENG) based on Au and TiO2 as the friction layers. Upon illumination, the current polarity rapidly reverses compared to the dark state. The negative and positive short-circuit current approximately increase by 12 and 2 times, respectively. Particularly, a photocurrent plateau appears due to the formation of metal-semiconductor Schottky contact in the device. By carefully analyzing the charge transfer in dark and under illumination, it is found that the accumulation of a large number of photoelectrons on the surface of TiO2 and the increase of conductivity are the reasons for the reversal current polarity and significant current increase under illumination. Our work provides a new approach for improving TENG output and a new understanding about the effect of surface states on the triboelectric performance especially the polarity of TENG.
关键词： ultrathin Au,photoelectrons,triboelectric polarity reversal,Triboelectric nanogenerator,TiO2 surface states
更新于2025-09-23 15:23:52
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A comprehensive study on the interface states in the ECR-PECVD SiO2/p-Si MOS structures analyzed by different method
摘要： The electrical properties of SiO2/p-Si films deposited by ECR-PECVD were studied at different frequencies (100-1 MHz) and gate voltages (-6–3 V). Results showed a frequency dispersion of C-Vg and G/ω-Vg. With increasing frequency, the capacitance and conductance are strongly decreased. An apparent peak in the depletion regime of the G/ω-Vg plots can be attributed to the existence of density Nss at Si/SiO2. The (Nss)value vary from 1.5 × 10^12 to 0.5 × 10^11 eV^-1 cm^-2, it has been determined by High-Low frequency capacitance technic. The Nss- Vg curve presents a peak at about -3 V, suggesting the presence Nss between the (Si)/SiO2 interface. Hill and Coleman method shows that the Nss decreases with increasing frequency which explains the high value of capacitance at low frequency. The Nss and their relaxation time τ by the conductance method ranged from 1.8 × 10^13 to 1.37 × 10^11 eV^-1 cm^-2 and 5.17 × 10^-7 to 8 × 10^-6 s, in the range (0.189-Ev) and (0.57- Ev) eV, respectively. The Nss was responsible for the non-ideal behavior of C-Vg and G-Vg leading to the breakdown of such device. Comparing the three method results show that parallel conductance is very precise and accurate.
关键词： Capacitance method,Relaxation time,Frequency,Interface states,Metal/Oxide/Semiconductor (MOS),Conductance method
更新于2025-09-23 15:23:52
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Depletion Layer Built-In Field at (1?100), (0001), and (000?1) GaN/Water Junction and Its Role in Semiconductor Nanowire Water Splitting
摘要： The nature of specific GaN plane/water interfaces under external bias and illumination can influence photoelectrolysis efficiency using GaN nanowires. Studies of Ga-polar, N-polar, and m-plane GaN interfaces with deionized water allow determining differences between surfaces corresponding to different nanowire facets. They are investigated under external bias conditions to reveal the profile of Fermi level localization through analysis of Franz–Keldysh oscillations using electrolyte electroreflectance (EER) technique in a specially designed measurement chamber. Calculation of the potential barrier height is also possible. EER study shows differences between surface densities of states (SDOS) at distinct GaN planes. One broad SDOS is identified near the conduction band in case of ±c-plane and related to Ga adatom reconstruction and β-Ga2O3 presence at the GaN electrode. Two narrow SDOS singularities are found at the m-plane one of which is localized near the middle of the bandgap and allows to generate approximately two times higher surface potential barrier than in case of polar surfaces at zero-bias conditions. This suggests that n-type GaN nanowires can enhance carrier separation at sidewalls and refine the oxygen evolution rate. Additionally, a voltage-controlled hysteresis loop of Fermi level localization is detected at the Ga-face GaN/water interface.
关键词： photoelectrolysis,m-plane,surface states,GaN,c-plane
更新于2025-09-23 15:23:52