Syfy has "decided not to renew" Alphas. Given its ratings during season two, most won't be surprised, even if they are disappointed. Here's the statement from Syfy:
Syfy has decided not to renew Alphas for a third season. We’ve been proud to present this entertaining, high-quality series for two seasons and to work with an incredible ensemble of talented actors, producers and creatives as well as our partners at BermanBraun Television. We’d like to thank the show’s dedicated regular viewers for their tremendous support.