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A.A. Chabanov, Abe Pena (UT-San Antonio) Jing Wang, A.Z. Genack (Queens College of CUNY) Speckle Fluctuations and Correlation
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Speckles
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Wave propagation in disordered media mean free path wavelength Field Intensity
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Average intensity: Gaussian statistics: only the pairs of identical paths have the same phase and thus give a contribution to the average intensity Wave diffusion in a disordered medium wavelength mean free path
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Diffusion equation for the average intensity: Wave diffusion in a disordered medium (This equation would yield the Ohm’s law for a disordered conductor)
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Wave interference A A*A* Probability of return: waveparticle transport reduction nonlocal correlation weak localization non-Gaussian statistics
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Transmission coefficients a′a′ b Transmitted intensity = speckle intensity Total transmission = brightness Transmittance = conductance a b′b′
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Transmission coefficients i.e., Beenakker, RMP (1997)
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Statistics of t ab and T ab Kogan & Kaveh, PRB (1995) AAC & Genack, PRA (2005)
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Alumina sample d=0.9 cm n=3.14 f=0.068 alumina sphere: copper tube: D=7.3 cm
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L=60 cm, 10,000 sample configurations A: ν =14.7-15.7 GHz, var( s ab )=1.18, diffusive wave B: ν =9.95-10.15 GHz, var( s ab )=6.18, localized wave C: t=740 ns, var[ s ab (t)]=20.1, strongly localized wave Transmission in alumina samples Frequency (GHz) time (ns) ABC σ = 5 MHz
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Transmitted field distribution Gaussian statistics:
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Characteristic and distribution functions of total transmission Nieuwenhuizen & vanRossen (1995) Stoytchev & Genack (1999)
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Factorizing of statistics of the field and intensity Fluctuations: Correlations:
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Correlation with polarization AAC, Hu & Genack (2004)
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Statistics of total transmission In localized regime (only one open channel):
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Statistics of transmission quantities in localized regime Pnini (2001)
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Correlation with wave polarization
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Intensity correlation of localized waves
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In a given random configuration, the statistics of transmitted field is Gaussian for both diffusive and localized waves; non- Gaussian mesoscopic field statistics arise in ensemble of configurations due to mesoscopic fluctuations of transmission In localized regime, the transmitted intensity can be written as a product of three statistically independent variables; two of them have Rayleigh distribution Future work: Conclusions In diffusive regime (many channels): ?
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