#  Seminar, Jürg Fröhlich (ETH Zurich), Physics in 2D – from the Kosterlitz-Thouless Transition to Topological Insulators, J356 

 



####  calendar\_today Date and Time 

 **March 20, 2018** 

 04:00PM - 04:00PM EDT 

####  pin\_drop Location 

 **Jefferson 356**  



 

 



 

   ![Frolich](/sites/g/files/omnuum6611/files/styles/hwp_1_1__720x720_scale/public/mathpicture/files/9497_frohlich.jpg?itok=oozIrLg6) 

 

 Title: Physics in 2D – from the Kosterlitz-Thouless Transition to Topological Insulators

 Abstract: A survey of “Physics in 2D” is presented: The Mermin-Wagner-McBryan-Spencer Theorem is recalled. Crucial ideas (among others, energy-entropy arguments for defects) in a proof of existence of the K-T transition in the 2D classical XY model are highlighted. Subsequently, the Topological-Field-Theory Approach to the Fractional Quantum Hall Effect and to 2D time-reversal invariant Topological Insulators with chiral edge spin-currents (1993) is described. The roles of anomaly cancellation, of braid statistics and of bulk-edge duality in the analysis of such systems are explained. Some general conclusions about Physics in two dimensions are outlined.

   ![Frolich](/sites/g/files/omnuum6611/files/styles/hwp_1_1__960x960_scale/public/mathpicture/files/frohlich_seminar_march_20_2018.png?itok=IK6nFWJH) 

 



 

 



 

 

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