The European Physical Journal B最新文献

A theoretical model of 工-shaped coupled-cavity waveguide with two quantum dots is proposed to realize the single photon router, where the two quantum dots are embedded in two nodes of two infinite coupled-cavity and a finite coupled-cavity waveguide respectively. Based on the discrete scattering equations, the routing properties such as transmission, reflection, and the transfer rate of the incident single photons are theoretically investigated. It is found that they can be controlled by various parameters such as the coupling strength between two quantum dots and three coupled-cavity waveguides, the transition energies of two quantum dots, wave vector, and the energy of the incident single photons, etc. Especially, when (omega_{e}^{(1)} = omega_{e}^{(2)} = 10), in case of (k = 2n{pi mathord{left/ {vphantom {pi 4}} right. kern-0pt} 4},(n = 1,2,...)),the incident single photons have two symmetric peaks with relative to the resonant energy, but in case of (k = (2n + 1){pi mathord{left/ {vphantom {pi 4}} right. kern-0pt} 4},(n = 0,1,2,...)), there appears only one transfer peak with blue or red shift due to the quantum interference between the two quantum dots. The tunable routing properties of the single photons in the 工-shape quantum router might have potential applications for future quantum devices.

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This study investigates the magnetic hysteresis properties of the C₆₀ and (C₆₀)₂ fullerene nanostructures according to the Blume–Emery–Griffiths model and Monte Carlo simulations. It seeks to know the influence of parameters such as exchange couplings, crystal field, and temperature on the magnetism of such materials. It was found that C₆₀ exhibited greater coercive and saturation fields than (C₆₀)₂ due to intra-cluster couplings and greater anisotropy. These results provide better understanding of the role of thermal fluctuations and structural stresses in magnetization reversal, which is crucial for magnetic nanomaterials development. These can be employed in spintronic devices, magnetic sensors, memory devices, nanoelectronics, and quantum computing.

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Structure, optoelectronic, and thermochemical characteristics of Li-based chalcopyrite materials LiXY₂ (X = Ga, Ti; Y = S, Se, Te) are studied using DFT approach. Geometry optimization and modeling of LiXY₂ are performed using several functionals like B3LYP/LANL2DZ, B3LYP/SDD, B3LYP/DEF2TZVP, CAM-B3LYP/LANL2DZ, CAM-B3LYP/SDD, CAM-B3LYP/DEF2TZVP, APFD/LANL2DZ, APFD/SDD, and APFD/DEF2TZVP within DFT framework and made a comparative analysis. It is found that functional B3LYP/DEF2TZVP provides the most suitable result. Using B3LYP/DEF2TZVP, the HOMO–LUMO gaps of LiGaS₂, LiGaSe₂ and LiGaTe₂ are determined as 3.34, 3.08, and 2.72 eV, respectively, whereas for LiTiS₂, LiTiSe₂, and LiTiTe₂, it is found as 2.71, 2.77, and 1.79 eV correspondingly, signifying their possible uses in optoelectronic devices and solar cells. It also specifies that the replacement of Ga with Ti in the host materials helps in the reduction of the energy gap, which exhibits its better absorption ability. The vertical ionization potential (VIP) as well as vertical electron affinity (VEA) of LiTiY₂ are found lesser in magnitude in comparison with LiGaY₂. LiTiTe₂ exhibits the lowest VIP, whereas LiGaTe₂ displays the maximum VEA, which indicates that LiTiTe₂ and LiGaTe₂ are suitable materials for hole and electron infusion, respectively. LiGaY₂ shows a high electronegativity as compared to LiTiY₂, which indicates that LiGaY₂ offers advantages to enhance electron and hole mobility. The refractive index for LiGaY₂ increases from LiGaS₂ to LiGaSe₂ to LiGaTe₂, while for LiTiY₂, the highest and the lowest magnitudes are observed for LiTiTe₂ and LiTiSe₂, respectively. Thermochemical properties of LiXY₂ are also computed.

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This editorial introduces the Topical Collection of The European Physical Journal B dedicated to Recent Advances in Complex Systems. Complex systems are characterized by multiple interacting components whose collective behavior exhibits nontrivial properties such as nonlinearity, emergence, and multiscale organization. This issue, inspired by the 2023 Conference on Complex Systems held in Salvador, Brazil, features contributions spanning diverse domains including physics, biology, economics, linguistics, and artificial intelligence. The selected papers are organized into five thematic areas: Complex Networks and Systemic Modeling; Financial, Natural and Environmental Dynamics; Advances in Computational Methods and AI; Biological and Health-Related Systems; and Fundamental Physics and Theoretical Systems. This collection reflects the interdisciplinary nature of the field and highlights its growing importance in addressing real-world challenges on systems-based thinking.

We present a time-dependent quantum calculations of the first-order and second-order photon correlation functions for the scattering of a single-photon pulse on a two-level atom (qubit) embedded in a one-dimensional open waveguide. Within Markov approximation we find the analytic expression for the quantum operator of positive frequency electric field. We restricted Hilbert space of initial states by the states with one and two excitations and show that the photon probability amplitudes are given by the off-diagonal matrix elements of the electric field operator between these states. For two-excitation initial state where the atom is excited and there exists a single photon in a waveguide we calculate the second-order correlation function which describes the measurements by two detectors at two different space-time points. The second-order correlation function exhibits the interference term showing that the measurements of two detectors are correlated. This interference is similar to that found in the Hanbury Brown and Twiss correlation experiment with two indistinguishable photons.

We investigate the dependence of quantum capacitance (left({C}_{text{Q}}right)) on the Fermi energy (left({E}_{text{F}}right)) in two-dimensional semiconductor materials belonging to the transition metal dichalcogenide (TMDC) family, taking into account the influences of external electric fields, Zeeman fields, and temperature. At low temperatures, distinct peaks and abrupt steps are clearly observed; whereas, at room temperature, these features are suppressed owing to thermal broadening from the Fermi–Dirac distribution. When external electric fields and Zeeman field components are introduced, the structure of ({C}_{text{Q}}) becomes more complex, exhibiting step-like features and deep valleys around the Fermi level. These reflect energy level splitting induced by spin–orbit coupling and valley polarization. A comparison among MoS₂, MoSe₂, WS₂, and WSe₂ reveals significant differences in the band gap width and density of states. These results demonstrate that the quantum capacitance in TMDCs is sensitive to external parameters, highlighting its potential for applications in quantum electronic devices, high-sensitivity sensors, and spintronic technologies based on two-dimensional materials.

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