Avoiding quantum chaos in quantum computation.
We study a one-dimensional chain of nuclear 1/2 spins in an external time-dependent magnetic field, considered as a possible candidate for experimental realization of quantum computation. According to the general theory of interacting particles, one of the most dangerous effects is quantum chaos that can destroy the stability of quantum operations. The standard viewpoint is that the threshold for the onset of quantum chaos due to an interaction between spins (qubits) strongly decreases with an increase of the number of qubits. Contrary to this opinion, we show that the presence of a nonhomogeneous magnetic field can strongly reduce quantum chaos effects. We give analytical estimates that explain this effect, together with numerical data supporting our analysis.
Berman
G P
GP
Theoretical Division and CNLS, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Borgonovi
F
F
Izrailev
F M
FM
Tsifrinovich
V I
VI