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BEGIN:VEVENT
DTSTAMP:20260817T033857Z
LAST-MODIFIED:20200102T184005Z
DTSTART:20200106T170000Z
DTEND:20200106T180000Z
UID:event2263@bu.edu
URL:http://physics.bu.edu/internal/events/show/2263
SUMMARY:Transient response of electronic collective modes in ultrafast meas
	urements
DESCRIPTION:Featuring Avraham Klein\, University of Minnesota\nHosted by: W
	anzheng Hu\n\nPart of the Biophysics/Condensed Matter Seminar Series.\n\nTh
	e collective modes in an itinerant electron system are a key manifestation 
	of its quantum correlations. Recent advances in in ultrafast pump-probe tec
	hnologies allow us to access subtle properties of these modes and to manipu
	late them for control of quantum states and phases. I will demonstrate this
	 by describing a nontrivial topological structure associated with correlati
	on functions of 2D Fermi liquids\, which manifests itself in unconventional
	 zero-sound propagating collective modes: "hidden" modes that don’t give 
	rise to peaks in the spectral function but still dominate the dynamics\, an
	d "mirage" modes that do give rise to peaks in spectroscopy but actually de
	cay faster than the single-particle scattering time. Both modes can be read
	ily identified via time-dependent measurements in pump-probe configurations
	. I will also present a theory of controlling the soft collective mode that
	 exists near a nematic quantum phase transition via nonlinear phonon excita
	tion. The theory describes both quasi-equilibrium control and quantum quenc
	hes\, and I will demonstrate its applicability to the unconventional superc
	onductor FeSe.
LOCATION:SCI 328\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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