Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 1Citation - Scopus: 1Completeness of Energy Eigenfunctions for the Reflectionless Potential in Quantum Mechanics(Aip Publishing, 2024) Erman, Fatih; Turgut, O. TeomanThere are a few exactly solvable potentials in quantum mechanics for which the completeness relation of the energy eigenstates can be explicitly verified. In this article, we give an elementary proof that the set of bound (discrete) states together with the scattering (continuum) states of the reflectionless potential form a complete set. We also review a direct and elegant derivation of the energy eigenstates with proper normalization by introducing an analog of the creation and annihilation operators of the harmonic oscillator problem. We further show that, in the case of a single bound state, the corresponding wave function can be found from the knowledge of continuum eigenstates of the system. Finally, completeness is shown by using the even/odd parity eigenstates of the Hamiltonian, which provides another explicit demonstration of a fundamental property of quantum mechanical Hamiltonians.Article Citation - WoS: 5Citation - Scopus: 5Nonreciprocal Transmission Enabled by Time Modulation of Penetrable Metasurface Assisted by Surface Waves(Aip Publishing, 2024) Yilmaz, H. Onder; Yaman, FatihThis study introduces a novel approach to achieving nonreciprocal transmission by implementing time modulation to the bianisotropic metasurface. For the first time, we present the analytical solution of the excitation of anti-symmetric surface waves on penetrable metasurfaces depending on the excitation direction. Exploiting this finding, we numerically demonstrate asymmetric control of the transmission coefficient under a fast-time scale by employing solely time modulation. This approach lowers the complexity of the modulation scheme and implementation encountered in the space-time modulation technique. We develop and simulate a 3D unit cell model in the microwave domain, which forms a surface cavity that incorporates time-varying capacitors. The impedance transfer matrix method and harmonic balance numerical solutions are applied to the retrieved equivalent circuit for the numerical simulations. The results reveal optimized phase-coherent and incoherent nonreciprocal transmission at the significant isolation level ( >= 40 dB) for forward and backward transmissions. We discuss the consistency and discrepancies between numerical methods and consider the impact of the losses and nonlinearity on the metastructure performance. (c) 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) licenseArticle Citation - WoS: 1Citation - Scopus: 1Quantum Transport Regimes in Quartic Dispersion Materials With Anderson Disorder(Aip Publishing, 2024) Polat, Mustafa; Ozkan, Hazan; Sevincli, HaldunMexican-hat-shaped quartic dispersion manifests itself in certain families of single-layer two-dimensional hexagonal crystals such as compounds of groups III-VI and groups IV-V as well as elemental crystals of group V. A quartic band forms the valence band edge in various of these structures, and some of the experimentally confirmed structures are GaS, GaSe, InSe, SnSb, and blue phosphorene. Here, we numerically investigate strictly one-dimensional and quasi-one dimensional (Q1D) systems with quartic dispersion and systematically study the effects of Anderson disorder on their transport properties with the help of a minimal tight-binding model and Landauer formalism. We compare the analytical expression for the scaling function with simulation data to distinguish the domains of diffusion and localization regimes. In one dimension, it is shown that conductance drops dramatically at the quartic band edge compared to the quadratic case. As for the Q1D nanoribbons, a set of singularities emerge close to the band edge, suppressing conductance and leading to short mean-free-paths and localization lengths. Interestingly, wider nanoribbons can have shorter mean-free-paths because of denser singularities. However, the localization lengths sometimes follow different trends. Our results display the peculiar effects of quartic dispersion on transport in disordered systems. (c) 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license