Holon Physics Seminar 16.11.17

13:00 16-11-2017
Simulatable and Unsimulatable Quantum Hall Effects: A Classification Based on Gravitational Anomalies
 
Dr. Zohar Ringel, Hebrew University of Jerusalem

November 16, 2017  | 13:00 | Seminar Room 424/8
 
 
Abstract:
It is believed that many quantum systems cannot be simulated efficiently using classical computational resources. This notion is supported by the fact that in quantum Monte Carlo (QMC) simulations of many important problems, it is not known how to express the partition function in a sign-free manner.
 
The answer to the question of whether there is a fundamental obstruction to having a sign-free representation for these problems remains unclear. In this talk I'll describe how gravitational anomalies act as obstructions to local sign-free QMC.
 
In condensed matter physics gravitational anomalies are intimately related to quantized thermal Hall response, a phenomena which occurs in various fractional quantum Hall effects. I'll also briefly discuss the connection between gravitational effects and sign problems in frustrated antiferromagnets and in certain critical two dimensional vertex models.