Breach pair superfluidity: a brief review.

Interior gap superfluidity was introduced together with Frank Wilczek. Later on together with our collaborators, we generalized this new possibility of superfluidity to a more broader concept, breach pair superfluidity. In the occasion to celebrate Professor Frank Wilczek's seventieth birthday and his productive career in several major areas in physics, I dedicate this note to recall the exciting times of developing this idea, the main aspects of the proposed phase, and discussion on its stability condition.