Filters

2013 - 20193

More filters

20203
Reset filters

Settings

DDC: 530 × Subject: mathematical computing ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Noise-Aided Logic in an Electronic Analog of Synthetic Genetic Networks
    (San Francisco, CA : Public Library of Science (PLoS), 2013) Hellen, E.H.; Dana, S.K.; Kurths, J.; Kehler, E.; Sinha, S.
    We report the experimental verification of noise-enhanced logic behaviour in an electronic analog of a synthetic genetic network, composed of two repressors and two constitutive promoters. We observe good agreement between circuit measurements and numerical prediction, with the circuit allowing for robust logic operations in an optimal window of noise. Namely, the input-output characteristics of a logic gate is reproduced faithfully under moderate noise, which is a manifestation of the phenomenon known as Logical Stochastic Resonance. The two dynamical variables in the system yield complementary logic behaviour simultaneously. The system is easily morphed from AND/NAND to OR/NOR logic.
  • Thumbnail Image
    Item
    A new color image encryption scheme using CML and a fractional-order chaotic system
    (San Francisco, CA : Public Library of Science (PLoS), 2015) Wu, X.; Li, Y.; Kurths, J.
  • Thumbnail Image
    Item
    Spectral dynamics of shift current in ferroelectric semiconductor SbSI
    (Washington : National Academy of Sciences, 2019) Sotome, M.; Nakamura, M.; Fujioka, J.; Ogino, M.; Kaneko, Y.; Morimoto, T.; Zhang, Y.; Kawasaki, M.; Nagaosa, N.; Tokura, Y.; Ogawa, N.
    Photoexcitation in solids brings about transitions of electrons/ holes between different electronic bands. If the solid lacks an inversion symmetry, these electronic transitions support spontaneous photocurrent due to the geometric phase of the constituting electronic bands: the Berry connection. This photocurrent, termed shift current, is expected to emerge on the timescale of primary photoexcitation process. We observe ultrafast evolution of the shift current in a prototypical ferroelectric semiconductor antimony sulfur iodide (SbSI) by detecting emitted terahertz electromagnetic waves. By sweeping the excitation photon energy across the bandgap, ultrafast electron dynamics as a source of terahertz emission abruptly changes its nature, reflecting a contribution of Berry connection on interband optical transition. The shift excitation carries a net charge flow and is followed by a swing over of the electron cloud on a subpicosecond timescale. Understanding these substantive characters of the shift current with the help of first-principles calculation will pave the way for its application to ultrafast sensors and solar cells.