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61.
62.
Miloš Dubajić Aleksandar Daničić Nikola Vuković Vitomir Milanović Jelena Radovanović 《Optical and Quantum Electronics》2018,50(10):373
In this work we theoretically investigate a possibility to use cubic nitride based multi-layer periodic nanostructure as a semiconductor metamaterial. The structure design is based on an active region of a quantum cascade laser optimized to achieve optical gain in the Terahertz (THz) spectral range. In particular, we test the GaN/AlGaN quantum well configurations, which should exhibit important advantages compared to GaAs-based structures, namely room temperature operation without the assistance of magnetic field and lower doping densities. Our numerical rate-equations model is solved self-consistently and it takes into account electron-longitudinal optical phonon scattering between all the relevant states among the adjacent periods of the structure. A global optimization routine, specifically genetic algorithm is then used to generate new gain-optimized structures. This work confirms the advantages of cubic GaN designs over GaAs ones, namely feasibility of negative refraction at room temperature without the assistance of magnetic field while keeping the doping densities of the same order of magnitude. 相似文献
63.
The idea that spacetime has to be replaced by Clifford space (C-space) is explored. Quantum field theory (QFT) and string
theory are generalized to C-space. It is shown how one can solve the cosmological constant problem and formulate string theory
without central terms in the Virasoro algebra by exploiting the peculiar pseudo-Euclidean signature of C-space and the Jackiw
definition of the vacuum state. As an introduction into the subject, a toy model of the harmonic oscillator in pseudo-Euclidean
space is studied. 相似文献
64.
N. M.??i?ovi? G. Lj.?Majstorovi? N.?Konjevi?Email author 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,32(3):347-354
Results of a Doppler spectroscopy study of hydrogen and deuterium
Balmer lines in the stainless steel and copper hollow cathode glow
discharge, operated in pure hydrogen, deuterium and mixtures of inert gases
with hydrogen, are reported. For all gases and gas mixtures plasma
observations perpendicular to electric field revealed the excessively large
Doppler broadening. By changing mode of glow discharge operation, the
Doppler broadened line profiles in helium-hydrogen mixture are recorded
parallel to the discharge electric field as well. The excessively broadened
part of the H line profile is shifted towards blue or red
wavelength by changing the direction of electric field vector. The presence
of large excessive Balmer lines broadening in pure hydrogen and in its gas
mixture with neon as well as shifting of the excessively broadened part of
line profile by means of electric field is in contradiction with the
resonance transfer model proposed by Mills et al. in several publications,
see e.g. [IEEE Trans. Plasma Sci. 31, 338 (2003)]. 相似文献
65.
Go A Bay A Abe K Aihara H Anipko D Aulchenko V Aushev T Bakich AM Barberio E Belous K Bitenc U Bizjak I Blyth S Bozek A Bracko M Browder TE Chang P Chao Y Chen A Chen KF Chen WT Cheon BG Chistov R Choi Y Choi YK Cole S Dalseno J Danilov M Dash M Drutskoy A Eidelman S Epifanov D Fratina S Gabyshev N Gershon T Gokhroo G Golob B Gorisek A Ha H Hastings NC Hayasaka K Hayashii H Hazumi M Heffernan D Hokuue T Hoshi Y Hou S Hou WS Iijima T Ikado K Imoto A Inami K Ishikawa A Ishino H Itoh R Iwasaki M 《Physical review letters》2007,99(13):131802
The neutral B meson pair produced at the Upsilon(4S) should exhibit a nonlocal correlation of the type discussed by Einstein, Podolsky, and Rosen. We measure this correlation using the time-dependent flavor asymmetry of semileptonic B(0) decays, which we compare with predictions from quantum mechanics and two local realistic models. The data are consistent with quantum mechanics, and inconsistent with the other models. Assuming that some B pairs disentangle to produce B(0) and B(0) with definite flavor, we find a decoherent fraction of 0.029 +/ -0.057, consistent with no decoherence. 相似文献
66.
67.
68.
Active-to-absorbing phase transition subjected to the velocity fluctuations in the frozen limit case
N. V. Antonov M. Hnatich A. S. Kapustin T. Lučivjanský L. Mižišin 《Physics of Particles and Nuclei Letters》2017,14(6):944-952
The directed bond percolation process is studied in the presence of compressible velocity fluctuations with long-range correlations. We discuss a construction of a field theoretic action and a way of obtaining its large scale properties using the perturbative renormalization group. The most interesting results for the frozen velocity limit are given. 相似文献
69.
We study linear response theory in the general framework of algebraic quantum statistical mechanics and prove the Green-Kubo formula and the Onsager reciprocity relations for heat fluxes generated by temperature differentials. Our derivation is axiomatic and the key assumptions concern ergodic properties of non-equilibrium steady states. 相似文献
70.
Rožič B Tzitzios V Karatairi E Tkalec U Nounesis G Kutnjak Z Cordoyiannis G Rosso R Virga EG Muševič I Kralj S 《The European physical journal. E, Soft matter》2011,34(2):1-11
We have studied theoretically and experimentally the effects of various types of nanoparticles (NPs) on the temperature stability range [Formula: see text] T (BP) of liquid-crystalline (LC) blue phases. Using a mesoscopic Landau-de Gennes type approach we obtain that the defect core replacement (DCR) mechanism yields in the diluted regime [Formula: see text] T (BP)(x) [Formula: see text] 1/(1 - xb) , where x stands for the concentration of NPs and b is a constant. Our calculations suggest that the DCR mechanism is efficient if a local NP environment resembles the core structure of disclinations, which represent the characteristic property of BP structures. These predictions are in line with high-resolution ac calorimetry and optical polarising microscopy experiments using the CE8 LC and CdSe or aerosil NPs. In mixtures with CdSe NPs of 3.5nm diameter and hydrophobic coating the BPIII stability range has been extended up to 20K. On the contrary, the effect of aerosil silica nanoparticles of 7.0nm diameter and hydrophilic coating is very weak. 相似文献