Speaker: Raymond Laflamme
Canada Research Chair in Quantum Information
Executive Director, Institute for Quantum Computing
Director, CIFAR QIP program, University of Waterloo
Thursday, April 29, 2010 4:00 p.m. Room: N1044

Abstract:

Information processing devices are pervasive in our society; from the
5dollar watches to multi-billions satellite network. These devices have
allowed the information revolution which is developing around us. It ha
stransformed not only the way we communicate or entertain ourselves but also
the way we do science and even the way we think. All this information is
manipulated using the classical approximation to the laws of physics, but we
know that there is a better approximation: the quantum mechanical laws.
Using quantum mechanics for information processing turns out not to be an
impediment but leads to a dramatic advantage for manipulating information.
The Achille's heel of quantum information is however its fragility. While
we are learning how to build quantum processor, we must learn to make them
robust: quantum error correction aims to do this. Quantum error correction
and its fault tolerant extension lead to the accuracy threshold theorem
which says that despite some noise, at a level below the threshold, it is
still possible to quantum compute efficiently. Underlying this theorem is an
assumption on noise models that hopefully are physically reasonable. This
talk will give a method to learn about the noise model for quantum
information processing device having in mind quantum error correction.
Standard methods for measuring the noise are based on quantum process
tomography and require an exponentially large numberof experiments. I will
describe protocols that will determine efficiently the probability of k
errors independently of which qubit is affected and which type of error it
is for memory based on the ideas described in Emerson et al. (Science 317,
1893, 2007). I will also discuss characterization of errors for one and two
bits gates based on the work of Knill ( arXiv:0707.0963). I will also
describe work on benchmarking of quantum gates whose goals is to assess the
performance of quantum information processors ( arXiv:0808.3973). I will
give an overview of experimental implementation on these ideas using NMR
inboth the liquid and solid-state.