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Robust topological BIC nanocavities for upconversion directional emission
Authors:
Yongqi Chen,
Ming Zhu,
Qingfeng Bian,
Xiumei Yin,
Wenxin Wang,
Bin Dong,
Yurui Fang
Abstract:
Photonic bound states in the continuum (BICs) provide a revolutionary paradigm for boosting light-matter interactions in integrated nanocavity systems. Nevertheless, precise manipulation of open cavity-emitter architectures still faces critical challenges, especially in realizing deterministic directional radiation and suppressing the perturbation of intrinsic cavity modes induced by emitters as l…
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Photonic bound states in the continuum (BICs) provide a revolutionary paradigm for boosting light-matter interactions in integrated nanocavity systems. Nevertheless, precise manipulation of open cavity-emitter architectures still faces critical challenges, especially in realizing deterministic directional radiation and suppressing the perturbation of intrinsic cavity modes induced by emitters as local impurities. Conventional investigations on cavity-emitter coupling are predominantly based on ensemble measurements, which inevitably mask the intrinsic physics underlying individual light-matter interactions. Here, we propose a robust strategy to control the upconversion and emission of a single-particle emitter using a topological plasmonic cavity with broken σh mirror symmetry. This structured design enables the transition from symmetry-protected BICs to a multi-BIC regime with finite but ultrahigh confinement, where nontrivial phase evolution and hybridization of transverse electric and magnetic modes open a well-defined far-field radiation channel for directional emission. Leveraging this scheme, we experimentally demonstrate dramatically enhanced radiation intensity from a single point-like emitter, together with uniform and deterministic directional emission, while achieving excellent structural robustness against local perturbations. This work establishes a general framework for engineering coherent directional light emission at the nanoscale, which lays a solid foundation for high-performance chip-scale integrated nanophotonic applications.
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Submitted 26 March, 2026;
originally announced March 2026.
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Discrete scale invariance of the quasi-bound states at atomic vacancies in a topological material
Authors:
Zhibin Shao,
Shaojian Li,
Yanzhao Liu,
Zi Li,
Huichao Wang,
Qi Bian,
Jiaqiang Yan,
David Mandrus,
Haiwen Liu,
Ping Zhang,
X. C. Xie,
Jian Wang,
Minghu Pan
Abstract:
Recently, log-periodic quantum oscillations have been detected in topological materials zirconium pentatelluride (ZrTe5) and hafnium pentatelluride (HfTe5), displaying intriguing discrete scale invariance (DSI) characteristic. In condensed materials, the DSI is considered to be related to the quasi-bound states formed by massless Dirac fermions with strong Coulomb attraction, offering a feasible p…
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Recently, log-periodic quantum oscillations have been detected in topological materials zirconium pentatelluride (ZrTe5) and hafnium pentatelluride (HfTe5), displaying intriguing discrete scale invariance (DSI) characteristic. In condensed materials, the DSI is considered to be related to the quasi-bound states formed by massless Dirac fermions with strong Coulomb attraction, offering a feasible platform to study the long-pursued atomic-collapse phenomenon. Here, we demonstrate that a variety of atomic vacancies in the topological material HfTe5 can host the geometric quasi-bound states with DSI feature, resembling the artificial supercritical atom collapse. The density of states of these quasi-bound states are enhanced and the quasi-bound states are spatially distributed in the "orbitals" surrounding the vacancy sites, which are detected and visualized by low-temperature scanning tunneling microscope/spectroscopy (STM/S). By applying the perpendicular magnetic fields, the quasi-bound states at lower energies become wider and eventually invisible, meanwhile the energies of quasi-bound states move gradually towards the Fermi energy (EF). These features are consistent with the theoretical prediction of a magnetic-field-induced transition from supercritical to subcritical states. The direct observation of geometric quasi-bound states sheds light on the deep understanding of the DSI in quantum materials.
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Submitted 8 March, 2023; v1 submitted 11 October, 2022;
originally announced October 2022.
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Scanning tunneling microscopic evidence of interface enhanced high-Tc superconductivity in Pb islands grown on SrTiO3
Authors:
Haigen Sun,
Zhibin Shao,
Zongyuan Zhang,
Yan Cao,
Shaojian Li,
Xin Zhang,
Qi Bian,
Habakubaho Gedeon,
Hui Yuan,
Jianfeng Zhang,
Kai Liu,
Zhong-Yi Lu,
Tao Xiang,
Qi-Kun Xue,
Minghu Pan
Abstract:
The discovery of the interface enhanced superconductivity in the single layer film of FeSe epitaxially grown on SrTiO3 substrates has triggered a flurry of activity in the field of superconductivity. It raised the hope to find more conventional high-Tc superconductors which are purely driven by the electron-phonon interaction at ambient pressure. Here we report the experimental evidence from the m…
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The discovery of the interface enhanced superconductivity in the single layer film of FeSe epitaxially grown on SrTiO3 substrates has triggered a flurry of activity in the field of superconductivity. It raised the hope to find more conventional high-Tc superconductors which are purely driven by the electron-phonon interaction at ambient pressure. Here we report the experimental evidence from the measurement of scanning tunneling spectroscopy for the interface enhanced high-Tc superconductivity in the Pb thin film islands grown on SrTiO3 substrates. The superconducting energy gap of the Pb film is found to depend on both the thickness and the volume of the islands. The largest superconducting energy gap is found to be about 10 meV, which is 7 times larger than that in the bulk Pb. The corresponding superconducting transition temperature, estimated by fitting the temperature dependence of the gap values using the BCS formula, is found to be 47 K, again 7 times higher than that of the bulk Pb.
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Submitted 23 November, 2018;
originally announced November 2018.
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Phonon Spectra and Thermal Properties of Some fcc Metals Using the Embedded-Atom Method
Authors:
Q. Bian,
S. K. Bose,
R. C. Shukla
Abstract:
By employing the analytic embedded-atom potentials of Mei {\it et al.} [Phys. Rev. B 43, 4653 (1991)] we have calculated the phonon dispersion spectra for six fcc metals: Cu, Ag, Au, Ni, Pd and Pt. We have also investigated thermal properties of these metals within the quasiharmonic approximation. Results for the lattice constants, coefficients of linear thermal expansion, isothermal and adiabat…
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By employing the analytic embedded-atom potentials of Mei {\it et al.} [Phys. Rev. B 43, 4653 (1991)] we have calculated the phonon dispersion spectra for six fcc metals: Cu, Ag, Au, Ni, Pd and Pt. We have also investigated thermal properties of these metals within the quasiharmonic approximation. Results for the lattice constants, coefficients of linear thermal expansion, isothermal and adiabatic bulk moduli, heat capacities at constant volume and constant pressure, Debye temperatures and Grüneisen parameters as a function of temperature are presented. The computed results are compared with the available experimental data. The comparison shows a generally good agreement between the calculated and experimental values for all thermodynamic properties studied. Isothermal and adiabatic bulk moduli and the specific heats are reproduced reasonably well, while the Grüneisen parameter and Debye temperature are underestimated by about 10%. The calculated phonon frequencies for Ag and Cu agree well with the results from inelastic neutron scattering experiments. However, there is considerable room for improvement in the phonon frequencies for Ni, Pd, Pt and Au, particularly at high phonon wave vectors close to the Brillouin zone boundary. The coefficient of linear thermal expansion is underestimated in most cases except for Pt and Au. The results are good for Pt up to 1000K and for Au up to 500 K.
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Submitted 14 September, 2006;
originally announced September 2006.