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METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20261018T141016Z
LAST-MODIFIED:20200225T191541Z
DTSTART:20200227T173000Z
DTEND:20200227T183000Z
UID:event2303@bu.edu
URL:http://physics.bu.edu/internal/events/show/2303
SUMMARY:Student March Meeting Talks
DESCRIPTION:Featuring Anirudh Chandrasekaran\, Mohit Pandey\, and Shiyu Zho
	u\, Boston University\nHosted by: Eric Boyers\n\nPart of the Graduate Stude
	nt Council Events.\n\nThis student seminar\, we will hear from several BU g
	raduate students about the work they will be presenting at the upcoming APS
	 March Meeting. Feedback for the speakers is welcome and encouraged!\n\nAni
	rudh Chandrasekaran - Catastrophe theory classification of Fermi surface to
	pological transitions\n\nAbstract: We classify all possible singularities i
	n the electronic dispersion of two-dimensional systems that occur when the 
	Fermi surface changes topology\, using catastrophe theory. For systems with
	 up to seven control parameters (i.e.\, pressure\, strain\, bias voltage\, 
	etc)\, the theory guarantees that the singularity belongs to to one of seve
	nteen standard types. We show that at each of these singularities the densi
	ty of states diverges as a power law\, with a universal exponent characteri
	stic of the particular catastrophe\, and we provide its universal ratio of 
	amplitudes of the prefactors of energies above and below the singularity. W
	e further show that crystal symmetry restricts which types of catastrophes 
	can occur at the points of high symmetry in the Brillouin zone. For each of
	 the seventeen wallpaper groups in two-dimensions\, we can list which catas
	trophes are possible at each high symmetry point.\n\nMohit Pandey - Detecti
	ng chaos using adiabatic gauge potential\n\nAbstract: Finding signatures of
	 chaos in the quantum world has been a long standing puzzle. We propose adi
	abatic gauge potential (AGP)\, which encodes the geometry of eigenstates wh
	en varying a control parameter in the Hamiltonian\, as an extremely sensiti
	ve diagnostic tool for quantum chaos. Frobenius norm of AGP shows remarkabl
	y different scaling with system size for integrable and chaotic systems: po
	lynomial versus exponential. Moreover\, AGP norm scaling can detect chaos a
	t exponentially small integrability-breaking strength\, which is orders of 
	magnitude smaller than what can be detected using mean ratio of two consecu
	tive level spacings.
LOCATION:SCI 352\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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