We analyze the pair production of charged particles in two-dimensional
Anti-de Sitter space (AdS_2) with a constant, uniform electric field. We
compute the production rate both at a semi-classical level, viewing Schwinger
pair production as a tunneling event, and at the full quantum level, by
extracting the imaginary part of the one-loop amplitude. In contrast to the
usual Schwinger pair production in flat space, pair production in AdS_2
requires a sufficiently large electric field E^2> M^2+1/4 in order to overcome
the confining effect of the AdS geometry -- put in another way, the presence of
an electric field E raises the Breitenlohner-Freedman bound to M^2 > -1/4 +
E^2. For E greater than this threshold, the vacuum is unstable to production of
charged pairs in the bulk. We expect our results to be helpful in constructing
supersymmetric AdS_2 X S^2 perturbative string vacua, which enter in the
near-horizon limit of extremal charged black holes. Although the generalized
Breitenlohner-Freedman bound is obeyed in these cases, production of BPS
particles at threshold is possible and relevant for AdS_2 fragmentation.Comment: 23 pages, 4 figures, v2:important revision, discussion of one-loop
amplitude extended, several references adde