SPECIAL Laboratory for Physical Sciences Seminar Announcement
Monday, October 18, 2010; 10 am
Seminar Room, Lower Level, LPS
8050 Greenmead Dr., College Park, MD 20740 301-935-6400
Title: Combining dynamical decoupling with fault-tolerant quantum computation
Daniel Lidar
Professor of Electrical Engineering and Chemistry at the University of
Southern California
Abstract:
This talk will be a not very technical presentation of the very
technical paper by the title above (arXiv:0911.3202, joint work with
Hui Ng and John Preskill), whose abstract reads as follows:
We study how dynamical decoupling (DD) pulse sequences can improve the
reliability of quantum computers. We prove upper bounds on the
accuracy of DD-protected quantum gates and derive sufficient
conditions for DD-protected gates to outperform unprotected
gates. Under suitable conditions, fault-tolerant quantum circuits
constructed from DD-protected gates can tolerate stronger noise, and
have a lower overhead cost, than fault-tolerant circuits constructed
from unprotected gates. Our accuracy estimates depend on the dynamics
of the bath that couples to the quantum computer, and can be expressed
either in terms of the operator norm of the bath’s Hamiltonian or in
terms of the power spectrum of bath correlations; we explain in
particular how the performance of recursively generated concatenated
pulse sequences can be analyzed from either viewpoint. Our results
apply to Hamiltonian noise models with limited spatial correlations.