Random approximation schemes for quantum spin chains without momentum

Random approximation schemes for quantum spin chains without momentum

Seminar author:Sofyan Iblisdir

Event date and time:05/25/2016 02:30:pm

Event location:GIQ Seminar room

Event contact:

A Monte Carlo exchange scheme for matrix product states is presented. It is meant as a tool towards a better understanding of mesoscopic spin chains with complex energy landscapes. The scheme is easy to implement; it operates on ensembles of configurations and couples Euclidean evolution with Metropolis moves. The resulting Markov chains are irreducible, aperiodic, sweep a compact configuration space, and half of them are reversible. As a result, eventual convergence to global minima of energy is guaranteed. But estimating mixing times is an open problem, even for uniformly gapped Hamiltonians. The power of the scheme is demonstrated in three case studies: a disordered ferromagnet, a quasi-periodic spin chain, and an antiferromagnet. A stable extension to 2+1 dimensions, i.e. projected entangled pair states, is next discussed.