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SUMMARY:When is a Hamiltonian Stoquastic? - Joel Klassen\, TU Delft
DTSTART:20190523T131500Z
DTEND:20190523T141500Z
UID:TALK124303@talks.cam.ac.uk
CONTACT:Johannes Bausch
DESCRIPTION:Finding the lowest energy of a Hamiltonian is a hard problem i
 n general\, however for many physical systems quantum Monte Carlo methods 
 can often be effectively applied to determine the lowest energy of a Hamil
 tonian\, and it is commonly understood that the absence of a sign problem 
 is a requisite condition for the success of these methods. The notion of s
 toquastic Hamiltonians was introduced with the aim of categorizing those H
 amiltonians which do not suffer from the sign problem. Indeed\, the study 
 of stoquastic Hamiltonians in the context of computational complexity theo
 ry has lent support to the notion that stoquastic Hamiltonians are somehow
  "simpler" than generic Hamiltonians. Importantly\, the property of being 
 stoquastic makes itself manifest only in a particular basis choice. In thi
 s work we explore how hard it is\, from a computational complexity perspec
 tive\, to find such a choice of basis. I will present an outline of an eff
 icient algorithm for deciding if a 2-local Hamiltonian\, with no 1-local t
 erms\, is stoquastic in some local basis.
LOCATION:MR13\, Centre for Mathematical Sciences\, Wilberforce Road\, Camb
 ridge
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