Speaker: Sir Anthony Leggett (Nobel Prize in Physics in 2003)
Title: The mean-field approach to superconductivity:is it adequate for quantum-information purposes?
Abstract: In the quest for a topologically protected quantum computer, much attention has been paid to systems such as Sr_2RuO_4 which are widely believed to realize Cooper pairing in the so-called (p+ip) state, which in turn is thought to realize non-Abelian anyonic excitations (Majorana fermions).However, almost without exception theoretical analysis of the behavior of these excitations has been carried out within the framework of mean-field theory as instantiated in the Bogoliubov-de Gennes equations.I point out that quite simple examples show that these equations are not always even qualitatively reliable, and argue that an improved approach may totally change the standard conclusions, in particular about the degree of topological protection afforded by Majorana fermions
Target audience: Publice and fellow NUS staff and students
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