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: 9
    Citation - Scopus: 9
    Non-Hermitian Hamiltonians for Linear and Nonlinear Optical Response: a Model for Plexcitons
    (AIP Publishing LLC, 2023) Finkelstein-Shapiro, Daniel; Mante, Pierre-Adrien; Balcı, Sinan; Zigmantas, Donatas; Pullerits, Tonu
    In polaritons, the properties of matter are modified by mixing the molecular transitions with light modes inside a cavity. Resultant hybrid light-matter states exhibit energy level shifts, are delocalized over many molecular units, and have a different excited-state potential energy landscape, which leads to modified exciton dynamics. Previously, non-Hermitian Hamiltonians have been derived to describe the excited states of molecules coupled to surface plasmons (i.e., plexcitons), and these operators have been successfully used in the description of linear and third order optical response. In this article, we rigorously derive non-Hermitian Hamiltonians in the response function formalism of nonlinear spectroscopy by means of Feshbach operators and apply them to explore spectroscopic signatures of plexcitons. In particular, we analyze the optical response below and above the exceptional point that arises for matching transition energies for plasmon and molecular components and study their decomposition using double-sided Feynman diagrams. We find a clear distinction between interference and Rabi splitting in linear spectroscopy and a qualitative change in the symmetry of the line shape of the nonlinear signal when crossing the exceptional point. This change corresponds to one in the symmetry of the eigenvalues of the Hamiltonian. Our work presents an approach for simulating the optical response of sublevels within an electronic system and opens new applications of nonlinear spectroscopy to examine the different regimes of the spectrum of non-Hermitian Hamiltonians.
  • Article
    Citation - WoS: 37
    Citation - Scopus: 62
    Suppression of Excited States Relative To the Ground State in Pb-Pb Collisions at S Nn = 5.02 Tev
    (American Physical Society, 2018) CMS Collaboration; Karapınar, Güler
    The relative yields of mesons produced in pp and Pb-Pb collisions at sNN=5.02 TeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states, (2S) and (3S), to the ground state, (1S), in both Pb-Pb and pp collisions at the same center-of-mass energy. The double ratios, [(nS)/(1S)]Pb-Pb/[(nS)/(1S)]pp, are measured to be 0.308±0.055(stat)±0.019(syst) for the (2S) and less than 0.26 at 95% confidence level for the (3S). No significant (3S) signal is found in the Pb-Pb data. The double ratios are studied as a function of collision centrality, as well as transverse momentum and rapidity. No significant dependencies are observed.