According to MIT Technology Review, the Pentagon has developed a prototype of the technology, code-named ‘Jetson,’ that uses infrared lasers to read a person’s cardiac signature.

Though far less obvious than fingerprints or faces, people’s heartbeats have a distinct profile, making them among the most useful biometrics for uniquely identifying a person.

What separates the signature from others like it, however, is the fact that unlike a face, which may bear many similar features to another, heartbeats are entirely distinct.