Colloquium Ehrenfestii - Dam Son (Chicago): "Emergent relativistic fermion on the half-filled Landau level"



19:30 hrs


Leiden, Main auditorium of the Oort building


Title:  Emergent relativistic fermion on the half-filled Landau level

Abstract: It is known that the composite fermion is a quasiparticle of the quantum Hall effect near half filling. Many years ago, Halperin, Lee and Read constructed a quantum field theory to describe the dynamics of the composite fermion. It has been long known, however, that this theory does not manifest the particle-hole symmetry on the lowest Landau level. I will describe how the particle-hole symmetry took a central role in recent theoretical discussions of the fractional quantum Hall effect; in particular, how a synthesis, motivated by the relativistic physics of graphene and topological insulators, has led to a new understanding of the low-energy quasiparticle of the half-filled Landau level. According to the new picture, the composite fermion behaves as a Dirac particle, similarly to the electron in graphene. Theoretical and experimental consequences of the new proposal are outlined.   

Please Note: The Colloquium Ehrenfestii takes place on Wednesday evenings starting at 19:30 hours in the main auditorium of the Oort building. Before the Colloquium, there is a common dinner in the canteen located on the ground floor of the Oort building. This dinner starts at 18:00 hours sharp and is FREE of charge, under the condition that one attends the colloquium and that one has made a reservation before noon on the Tuesday preceding the colloquium.  

The registration form is only accessible from within the University (to block spammers); if you would like to register for the dinner from outside the University, please send an email to   The revolving doors to the Oort building  are accessible until 9 pm after that they are locked and one should instead use the sliding doors directly adjacent to the Huygens building: these can be opened with an electronic key (seek help from locals).