BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-3768
DTSTART:20151112T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260419T110402Z
LAST-MODIFIED:20151027T194433Z
LOCATION:5310 Chamberlin Hall
SUMMARY:Topological Quantum Matter\, R. G. Herb Condensed Matter Semin
 ar\, Yong Chen \, Purdue University
DESCRIPTION:Topological quantum matter (TQM)\, where topological order
  or topological invariants are used to distinguish different phases of
  matter\, has emerged as a major paradigm in condensed matter physics 
 in recent years.  TQMs feature topological bulk-boundary correspondenc
 es\, where some nontrivial topologically-protected boundary modes are 
 guaranteed to emerge due to the topologically nontrivial states in the
  bulk of the system.  The first example of TQM is the well-known quant
 um Hall (QH) effect of two-dimensional electrons in a perpendicular ma
 gnetic field\, where the bulk is insulating due to energy gaps from La
 ndau level formation\, and topological conduction free of backscatteri
 ng occurs via chiral edge states\, giving rise to quantized Hall condu
 ctance in units of e2/h that is now used as a quantum metrology to hel
 p define “ohm” or the even Planck constant itself.  The list of TQ
 Ms has dramatically expanded in the past decade to now include new sta
 tes of matter such as topological insulators (TI)\, which can be a gen
 eralization of the QH states to three dimensions and zero magnetic fie
 ld due to the presence of strong spin orbit coupling (SOC)\, giving ri
 se to a gapped insulator in the bulk and conducting spin-helical Dirac
  fermions on the surface promising for spintronics and other applicati
 ons\; topological semimetals\, which realize 3D Dirac or Weyl fermions
  that can exhibit a condensed matter version of the “chiral anomaly�
 ��\; topological superconductors\, which could host quasiparticle anal
 ogues of “majorana fermions” potentially useful as qubits for “t
 opological” quantum computation. While so far mostly studied for ele
 ctronic systems\, it is also possible to engineer “synthetic” gaug
 e fields or SOC that may help realize analogous or new kinds of TQMs f
 or photons or neutral atoms. This talk will overview some of the key p
 hysics and promised device applications\, and describe efforts in my g
 roup to make\, improve and characterize TQMs --- a particular focus in
  the past few years has been to realize truly intrinsic TIs that demon
 strate salient signatures of “topological” transport\, such as a t
 hickness independent conductance in thin films\, “half-integer” Di
 rac fermion QH effects and helical spin polarized current characterist
 ic of topological surface states (TSS)\, and a “half-integer” Ahar
 onov-Bohm effect when such TSS are confined in a (cylindrical) curved 
 space. Such TIs could also be used as a starting point to make topolog
 ical semimetals and superconductors.  
URL:https://www.physics.wisc.edu/events/?id=3768
END:VEVENT
END:VCALENDAR