Measuring information growth in fractal phase space

We look at chaotic systems evolving in fractal phase space. The entropy change in time due to the fractal geometry is assimilated to the information growth through the scale refinement. Due to the incompleteness, at any scale, of the information calculation in fractal support, the incomplete normalization $\sum_ip_i^q=1$ is applied throughout the paper. It is shown that the information growth is nonadditive and is proportional to the trace-form $\sum_ip_i-\sum_ip_i^q$ so that it can be connected to several nonadditive entropies. This information growth can be extremized to give, for non-equilibrium systems, power law distributions of evolving stationary state which may be called ``maximum entropic evolution''.Comment: 10 pages, 1 eps figure, TeX. Chaos, Solitons & Fractals (2004), in pres

Determination of anisotropic dipole moments in self-assembled quantum dots using Rabi oscillations

By investigating the polarization-dependent Rabi oscillations using photoluminescence spectroscopy, we determined the respective transition dipole moments of the two excited excitonic states |Ex> and |Ey> of a single self-assembled quantum dot that are nondegenerate due to shape anisotropy. We find that the ratio of the two dipole moments is close to the physical elongation ratio of the quantum dot.Comment: 11 pages, 2 figures, MS Word generated PDF fil

Maximum Path Information and Fokker-Planck Equation

We present in this paper a rigorous method to derive the nonlinear Fokker-Planck (FP) equation of anomalous diffusion directly from a generalization of the principle of least action of Maupertuis proposed by Wang for smooth or quasi-smooth irregular dynamics evolving in Markovian process. The FP equation obtained may take two different but equivalent forms. It was also found that the diffusion constant may depend on both q (the index of Tsallis entropy) and the time t.Comment: 7 page

Pressure induced Raman and fluorescence singularities in LiYF4LiYF_4

The pressure effect on the fluoride scheelite laser host $LiYF_4$ is studied at room temperature up to 26 GPa by Raman scattering and up to 40 GPa by $P^{3+}$ fluorescence of doped sample. The Raman spectra exhibit three singularities at the vicinity of 6 GPa, 10-12 GPa and 16-17 GPa. The samples pressurized to 21 GPa or higher do not recover the original phase after being released, giving more Raman lines than original samples. The luminescence spectra of $P^{3+}$ are collected in the energy range corresponding to following transitions $^3P_{0,1}--^3H_{4,5,6}$, $^1D_2--^3H_4$ and $^3P_0--^3F_2$. Singularities are observed in the vicinity of 6 GPa, 10 GPa, 16 GPa, 23 GPa in agreement with the Raman study. Moreover, an irreversible transition occurs at 23 GPa. The samples pressurized to above 26 GPa become amorphous when released and all the sharp lines disappear. Above 31 GPa, the spectra at high pressures show only some broad bands corresponding to transitions between two multiplets of the $^4F_2$ configuration of $Pr^{3+}$. These singularities suggest possible phase transformations leading to lowering of the lattice symmetry.Comment: 12 pages, 13 figures, 2 table, LaTe

Symbol error rate analysis for M-QAM modulated physical-layer network coding with phase errors

Recent theoretical studies of physical-layer network coding (PNC) show much interest on high-level modulation, such as M-ary quadrature amplitude modulation (M-QAM), and most related works are based on the assumption of phase synchrony. The possible presence of synchronization error and channel estimation error highlight the demand of analyzing the symbol error rate (SER) performance of PNC under different phase errors. Assuming synchronization and a general constellation mapping method, which maps the superposed signal into a set of M coded symbols, in this paper, we analytically derive the SER for M-QAM modulated PNC under different phase errors. We obtain an approximation of SER for general M-QAM modulations, as well as exact SER for quadrature phase-shift keying (QPSK), i.e. 4-QAM. Afterwards, theoretical results are verified by Monte Carlo simulations. The results in this paper can be used as benchmarks for designing practical systems supporting PNC. © 2012 IEEE