Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.
To add your name to the Quantum Lunch email list, contact Charlotte Lehman

Thursday, May 12, 2010
12:30 PM - 2:00 PM

Speaker: Sevag Gharibian (University of Waterloo)

Technical Host: Rolando Somma

TOPIC: Approximation algorithms for QMA-complete problems

Abstract
Approximation algorithms for classical constraint satisfaction problems are one of the main research areas in theoretical computer science. Here we define a natural approximation version of the QMA-complete local Hamiltonian problem and initiate its study. We present two main results. The first shows that a non-trivial approximation ratio can be obtained in the class NP using product states. The second result (which builds on the first one), gives a polynomial time algorithm providing a similar approximation ratio for dense instances of the problem. The latter result is based on an adaptation of the "exhaustive sampling method" by Arora et al. [J. Comp. Sys. Sci., vol. 58, 1999] to the quantum setting, and might be of independent interest.

This is joint work with Julia Kempe. I will attempt to make the talk accessible to both computer scientists and physicists.