940 research outputs found
Josephson surface plasmons in spatially confined cuprate superconductors
In this work, we generalize the theory of localized surface plasmons to the
case of high-Tc cuprate superconductors, spatially confined in the form of
small spherical particles. At variance from ordinary metals, cuprate
superconductors are characterized by a low-energy bulk excitation known as the
Josephson plasma wave (JPW), arising from interlayer tunneling of the
condensate along the c-axis. The effect of the JPW is revealed in a
characteristic spectrum of surface excitations, which we call Josephson surface
plasmons. Our results, which apply to any material with a strongly anisotropic
electromagnetic response, are worked out in detail for the case of multilayered
superconductors supporting both low-frequency (acoustic) and transverse-optical
JPW. Spatial confinement of the Josephson plasma waves may represent a new
degree of freedom to engineer their frequencies and to explore the link between
interlayer tunnelling and high-Tc superconductivity
Hyperbolic metamaterials based on quantum-dot plasmon-resonator nanocomposites.
We theoretically demonstrate that nanocomposites made of colloidal semiconductor quantum dot monolayers placed between metal nanoparticle monolayers can function as multilayer hyperbolic metamaterials. Depending on the thickness of the spacer between the quantum dot and nanoparticle layers, the effective permittivity tensor of the nanocomposite is shown to become indefinite, resulting in increased photonic density of states and strong enhancement of quantum dot luminescence. This explains the results of recent experiments [T. Ozel et al., ACS Nano 5, 1328 (2011)] and confirms that hyperbolic metamaterials are capable of increasing the radiative decay rate of emission centers inside them. The proposed theoretical framework can also be used to design quantum-dot/nanoplasmonic composites with optimized luminescence enhancement. © 2014 Optical Society of America
Channel spaser
We show that net amplification of surface plasmons is achieved in channel in
a metal plate due to nonradiative excitation by quantum dots. This makes
possible lossless plasmon transmission lines in the channel as well as the
amplification and generation of coherent surface plasmons. As an example, a
ring channel spaser is considered
Experimental study of the decay PHI(1020)--->ETA+GAMMA in multi-photon final state
In the SND experiment at VEPP-2M e^+e^- collider the phi(1020) ---> eta+gamma
---> 3pi^0+gamma decay was studied. The branching ratio B(phi--->eta+gamma) =
(1.246 +- 0.025 +- 0.057)% was measured.Comment: 4 pages, 1 figure, 1 table, Submitted to JETP Let
Evidence of phi --> pi0 pi0 gamma and phi --> pi0 eta gamma decays in SND experiment at VEPP-2M
Preliminary results on the study of e+e- --> phi(1020) --> pi0 pi0 gamma, eta
pi0 gamma processes from SND experiment at VEPP-2M collider in Novosibirsk are
presented. Branching ratios of rare radiative phi --> pi0 pi0 gamma and phi -->
pi0 eta gamma decays are measured:
B(phi --> pi0 pi0 gamma ) = (1.1 +- 0.2) * 10^-4
(invariant mass (pi0 pi0) < 800 MeV),
B(phi --> eta pi0 gamma ) = (1.3 +- 0.5) * 10^-4.Comment: Talk at the HADRON97 conference, BNL, Aug 24-30 1997; LaTeX, 4 pages,
4 eps figure
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