  In the recent paper Terhal and Burkard derived a threshold result for
fault-tolerant quantum computation under the assumption of the non-Markovian
noise and claimed to rebut the objections rised by Alicki and Horodecki's. The
purpose of this note is to show that the main condition used by Terhal and
Burkard, although looking quite innocently, implies the assumption of the
extremally low probability error per single quantum gate - p < 10^{-8} -
10^{-12} - i.e. the square of the expected threshold value for the case of
Markovian noise.
