  Current methods of preparing maximally entangled states in the laboratory
need an extremely accurate control of interaction times, requiring
sophisticated experimental techniques.
  Here, we show that such precise control is not necessary when one utilizes
short or weak interactions followed by measurements. We present a scheme for
the probabilistic generation of Bell states in a pair of cavities, after each
has interacted briefly with an atom. The advantage of this proposal, as
compared to present schemes, is its low sensitivity to the exact values of
experimental parameters such as atomic velocity and coupling strength, in fact,
for a large range of parameters the fidelity of the Bell states generated
remains close to unity.
