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Speakers: Alexander Monin (Lausanne), Oleksandr Gamayun (Amsterdam) and Mikael Fremling (Utrecht). Location: Leiden

Event details of Triangle meeting Quantum and Topological matter
Date 15 February 2019
Time 14:00 -18:00


14:00 - 14:30 Welcome coffee and  tea

14:30 - 15:20 Alexander Monin (Lausanne) - Effective Field Theory for CFTs with large charge

15:20 -16:00 Oleksandr Gamayun (Amsterdam) - Relaxation in classical integrable systems 

16:00 - 16:30 Coffee, Tea

16:30 - Mikael Fremling (Utrecht) - Hall Viscosity and Composite Fermions

Drinks and snacks afterwards


Alexander Monin (Lausanne) - Effective Field Theory for CFTs with large charge

In a generic conformal field, theory the spectrum of operators carrying a large U (1) charge can be analyzed semiclassically. The key is the operator state correspondence by which such operators are associated with a finite density superfluid phase for the theory quantized on the cylinder. The dynamics is dominated by the corresponding Goldstone hydrodynamic mode and the derivative expansion coincides with the inverse charge expansion. I will illustrate this situation by first considering simple quantum mechanical analogues and then will systematize the approach by employing the coset construction for non-linearly realized space-time symmetries. Focussing on a 3-dimensional theory, I will illustrate that the three point function coefficients turn out to satisfy universal scaling laws and correlations as the charge and spin are varied. Lastly, I’ll show how the approach can be generalized to the case of large spin by considering vortices in the superfluid. 

Oleksandr Gamayun (Amsterdam) - Relaxation in classical integrable systems 

I will consider non-equilibrium dynamics in the classical integrable systems. Integrability techniques allow finding the exact form of the large time asymptotic profile, which I will present as an analog of the Eigenstate State Thermalization Hypothesis. My main examples will be relaxation dynamics in one-dimensional Bose gases, formulated as an initial value problem for the classical nonlinear Schrodinger equation and domain wall "melting” in XXZ magnetic. 

Mikael Fremling (Utrecht) - Hall Viscosity and Composite Fermions 

In this talk, I will review the connection between the topological "shift", which can be used to differentiate between fractional quantum hall trial wave functions, and the anti-symmetric (Hall) viscosity response of a 2D-fluid. The "shift", which is easy to establish theoretically, will be difficult (probably impossible) to measure directly in experiments, but the hope is that the topological characteristics will make itself known through other measurable properties, such as the aforementioned Hall viscosity. To theoretically compute Hall viscosity one may compute the Berry curvature related to area deformations on a flat geometry (i.e. a torus). However to write down wave functions for the torus (except in the simplest cases) has proven much more difficult than for the spherical geometry and infinite plane. I will then discuss the latest developments in constructing composite fermion trial wave functions on the torus, and touch upon the importance of modular covariance as a physical constraint of the wave function.


Location: Leiden University, Huygens Lab, HL 226

Niels Bohrweg 2, Leiden. >>Googlemaps 


Vadim Cheianov (Leiden)