  Rydberg blockade of ultracold atoms is considered now as one of the most
promising tools for the implementation of quantum computing, but its fidelity
can be substantially compromised by detrimental excitation of the neighbouring
atoms. This phenomenon has been investigated recently in detail for the
particular case of molecular resonances (i.e., resulting in the formation of
quasi-bound states). However, as will be shown in the present paper, an even
greater effect can come from the non-molecular resonances, which therefore
should be taken into account very carefully.
