Written by a renowned quantum physicist closely involved in the U.S. government's development of quantum information science, this book presents an inside look at the government's quest to build a quantum computer capable of solving complex mathematical problems and hacking the public-key encryption codes used to secure the Internet. The "killer app" refers to Shor's quantum factoring algorithm, which would unveil the encrypted communications of the entire Internet if a quantum computer could be built to run the algorithm. Schrodinger's notion of quantum entanglement-and his infamous cat-is at the heart of it all.