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SUMMARY:Theory of g factors in semiconductors — some history\, and new i
 nsights - David DiVincenzo (Forschungszentrum Jülich &amp\; JARA Institut
 e for Quantum Information\, Aachen)
DTSTART:20251029T161500Z
DTEND:20251029T171500Z
UID:TALK239500@talks.cam.ac.uk
CONTACT:Andrea Pizzi
DESCRIPTION:The g factor of electrons and holes in crystals and heterostru
 ctures of silicon\, germanium\, gallium arsenide\, etc.\, is a key paramet
 er in designing spin qubits. I will begin by discussing two different but 
 interrelated definitions of the g factor. Authors have disagreed from the 
 beginning about whether or not g is a symmetric second-rank tensor. I will
  discuss that g\, which is specific to each eigenstate\, whether extended 
 or localized\, is best discussed in terms of three singular values associa
 ted with eigendirections\, with a separate discussion about its sign. Lutt
 inger gave a correct formula for the g factors of band electrons\, includi
 ng the orbital contributions arising from the spin-orbit interaction. But 
 it was not until fifty years later\, with the advent of Berry-curvature co
 ncepts\, that his formula could be given a clear physical interpretation. 
 I will show results of a survey we have done of band g factors in silicon 
 and germanium\, emphasizing new topological aspects. It is interesting tha
 t even silicon\, with its very weak spin-orbit interaction\, can\, because
  of a combination of topology and symmetry\, exhibit g factors very far fr
 om 2.\n\n_If you wish to meet the speaker\, please contact ap2076@cam.ac.u
 k to be added to their visit schedule._
LOCATION:Ray Dolby Auditorium\, Ray Dolby Centre\, Cavendish Laboratory\, 
 JJ Thomson Avenue\, CB3 0US
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