Hi all,
next week, we have a talk by Jeongwan Haah on Wednesday at 4pm in
the Time Room.
Best wishes,
Markus
Title: Demonstration of self-correcting quantum memory in three
dimensions
Speaker: Jeongwan Haah (IQI Caltech)
Abstract:
Based on the joint work with Sergey Bravyi, IBM Watson.
We show that any topologically ordered local stabilizer model of
spins
in three dimensional lattices that lacks string logical operators
can
be used as a reliable quantum memory against thermal noise. It is
shown that any local process creating a topologically charged
particle
separated from other particles by distance $R$, must cross an energy
barrier of height $c \log R$. This property makes the model glassy.
We
devise an efficient decoding algorithm that should be used at the
final read-out, and prove a lower bound on the memory time until
which
the fidelity between the outcome of the decoder and the initial
state
is close to 1. The memory time increases as $L^{\beta}$ where $L$ is
the system size and $\beta$ the inverse temperature, as long as
$L<
L^\star \sim e^\beta$. Hence, the optimal memory time scales as
$e^{\beta^2}$.
Our bound applies when the system interacts with
thermal bath via a Markovian master equation. We give an example of
3D
local stabilizer codes that satisfies all of our assumptions. We
numerically verify for this example that our bound is tight up to
constants.
Date: March 07, 2012 - 4:00 pm
Series: Perimeter Institute Quantum Discussions
Location: Time Rm