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DTSTAMP:20260909T190719Z
LAST-MODIFIED:20150908T140501Z
DTSTART:20150916T153000Z
DTEND:20150916T163000Z
UID:event1461@bu.edu
URL:http://physics.bu.edu/internal/events/show/1461
SUMMARY:Bound states of Higgs modes in a superfluid
DESCRIPTION:Featuring Ippei Danshita\n\nPart of the Condensed Matter Theory
	 Seminar Series.\n\nWe study collective modes of superfluid Bose gases in o
	ptical lattices combined with potential barriers [1]. We assume that the sy
	stem is in the vicinity of the quantum phase transition to a Mott insulator
	 at a commensurate filling\, where emergent particle-hole symmetry gives ri
	se to two types of collective mode\, namely\, a gapless Nambu-Goldstone (NG
	) phase mode and a gapful Higgs amplitude mode. We consider two kinds of po
	tential barrier: one does not break the particle-hole symmetry while the ot
	her does. Including effects of both kinds of barrier\, we derive the Ginzbu
	rg-Landau equation for the superfluid order parameter. In the presence of t
	he former barrier\, we find bound states of Higgs mode that have binding en
	ergies lower than the gap of the Higgs mode in bulk and are localized aroun
	d the barrier. We also analyze tunneling properties of the NG mode incident
	 to both barriers. It is shown that the latter barrier couples the Higgs bo
	und states with the NG mode\, leading to Fano resonance mediated by the bou
	nd states. Finally\, we present a quantum field theoretical description of 
	the collective modes\, including the Higgs bound states\, in the presence o
	f both types of barriers.\n[1] T. Nakayama\, I. Danshita\, T. Nikuni\, and 
	S. Tsuchiya\, arXiv:1503.01516v2 (2015).
LOCATION:SCI 328\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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