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SUMMARY:Atomic Collapse in Graphene
DTSTART:20151013T161500
DTSTAMP:20260411T110648Z
UID:ae317a6c64217e797531127d8376d4e1fcf0435f472285debdfc2b70
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Leonid Levitov\, MIT\nBio: Leonid Levitov published over
  a hundred refereed papers and reviews in the fields of quantum transport\
 , nano-electronics\, solid-state quantum computing\, cold atoms\, quantum 
 noise\, growth and pattern formation\, which can be found at the home page
  http://www.mit.edu/~levitov. He pioneered in the theory of quasicrystals\
 , orderly materials with non-crystallographic symmetries discovered in 198
 5. Leonid co-authored a theory explaining the structural properties of qua
 si-crystals by introducing the concept of a structure projected from a hig
 h-dimensional periodic structure.\nIn the 90's\, he pioneered in the theor
 y of quantum noise. Leonid formulated the counting statistics approach\, w
 hich evolved into a new tool in the field of quantum transport. In 1993\, 
 he developed the concept of coherent current pulses allowing the transmiss
 ion of electrical signals in a noise-free fashion. These pulses\, observed
  in 2013 and dubbed 'levitons'\, have become the basis of electron optics.
  In the last 10 years\, Leonid developed theory of electronic properties o
 f graphene\, a newly discovered two-dimensional electron system.\nSince th
 e discovery that electrons in graphene behave as massless Dirac fermions\,
  the single-atom- thick material has become a fertile playground for testi
 ng exotic predictions of quantum electrodynamics\, such as Klein tunneling
  and the fractional quantum Hall effect. Now add to that list atomic colla
 pse\, the spontaneous formation of electrons and positrons in the electros
 tatic field of a super-heavy atomic nucleus.\nThe atomic collapse was pred
 icted to manifest itself in quasi-stationary states which have complex-val
 ued energies and which decay rapidly. However\, the atoms created artifici
 ally in laboratory have nuclear charge only up to Z = 118\, which falls sh
 ort of the predicted threshold for collapse. Interest in this problem has 
 been revived with the advent of graphene\, where because of a large fine s
 tructure constant the collapse is expected for Z of order unity.\nIn this 
 talk we will discuss the symmetry aspects of atomic collapse\, in particul
 ar the anomalous breaking of scale invariance. We will also describe recen
 t experiments that use scanning tunneling microscopy (STM) to probe atomic
  collapse near STM-controlled artificial compound nuclei.
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
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