The fractional quantum Hall effect (FQHE) in the lowest Landau level (LLL) is understood in a unified manner in terms of composite fermions, which are bound states of electrons and vortices. The strongest states in the LLL are understood as integer quantum Hall states of composite fermions and the compressible 1/2 state as a Fermi liquid of composite fermions. For the FQHE in the second LL, such a unified description does not exist: experimentally observed states are described by different physical mechanisms. In this talk I will discuss our first steps towards such a unified understanding of states in the second LL in terms of partons, which are a generalization of composite fermions. I will elucidate in detail our recent work on a parton construction of a wave function to describe the enigmatic FQH state at 5/2 (see Ref). A major advantage of this parton construction is that its wave function can be evaluated for very large systems, which makes it amenable to variational calculations. I will end with the tantalizing observation that two parton sequences could capture most of the observed fractional quantum Hall states in the second LL.
The plan of the talk is to first describe FQHE in the LLL and then go on to the states in the second LL.
Ref: Ajit C. Balram, Maissam Barkeshli, Mark S. Rudner, Parton construction of a wave function in the anti-Pfaffian phase, arXiv:1803.10427
We would like to invite you to suggest speakers from local groups or visitors for any slot that is not filled yet. Looking forward to seeing you there!
16 April 2018 (Monday): Kristof Harms (University of Goettingen, Germany)
25 April 2018 (Wednesday): Søren Ulstrup (Aarhus University, Denmark)