Summary: Polynomial Simulations of Decohered Quantum Computers
Dorit Aharonov and Michael Ben­Or
The Hebrew University, Jerusalem, Israel
Abstract
Recently it has become clear, that a key issue in
quantum computation is understanding how interac­
tion with the environment, or ``decoherence'', effects
the computational power of quantum computers. We
adopt the standard physical method of describing sys­
tems which are interwound with their environment by
``density matrices'', and within this framework define a
model of decoherence in quantum computation.
Our results show that the computational power of
decohered quantum computers depends strongly on the
amount of parallelism in the computation. We first
present a simulation of decohered sequential quantum
computers, on a classical probabilistic Turing machine,
and prove that the expected slowdown of this simulation
is polynomial in time and space of the quantum com­
putation, for any non zero decoherence rate. Similar

Source: Aharonov, Dorit - School of Computer Science and Engineering, Hebrew University of Jerusalem

Collections: Physics; Computer Technologies and Information Sciences