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DTSTAMP:20260905T204043Z
LAST-MODIFIED:20121116T203436Z
DTSTART:20090508T160000Z
DTEND:20090508T170000Z
UID:event437@bu.edu
URL:http://physics.bu.edu/internal/events/show/437
SUMMARY:Dicke superradiance and Anderson localization of photons
DESCRIPTION:Featuring Eric Akkermans\, Yale University\nHosted by: Bennett 
	Goldberg\n\nPart of the Biophysics/Condensed Matter Seminar Series.\n\nAbst
	ract: It is generally accepted that coherent multiple scattering of photons
	 in a gas of randomly distributed atoms leads eventually\, for a strong eno
	ugh disorder\, to a localized phase where photons are trapped within the ga
	s for extremely long times. The main characteristics of this zero temperatu
	re phase transition named after P.W. Anderson are well known and they will 
	be briefly presented. In an atomic gas\, however\, there exist cooperative 
	effects which change considerably the photon escape rates and the long rang
	e atomic dipolar interactions. The resulting enhanced (superradiance) ordec
	reased (subradiance) emission thus competes with localization effects which
	 are very sensitive to long range correlations between scatterers. The purp
	ose of this talk is to compare the two phenomena and to show that for stron
	g enough disorder\, photons become localized but this localization appears 
	as a smooth crossover which is primarily determined by cooperative effects 
	rather than by disorder. This crossover is studied in detail using a univer
	sal scaling function whose behavior is obtained both from a microscopic ana
	lysis and from a modified stochastic Markov process which shares a lot of s
	imilarities with "small world networks" well documented in statistical mech
	anics.
LOCATION: \, \, 
STATUS:CONFIRMED
CLASS:PUBLIC
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