Quantum is a color vector arcade video game developed at General Computer Corporation for Atari, Inc. and released in November 1982.

As the attract-mode demo explains, the idea is to circle around and cross your tail to complete a loop.

A level is completed by destroying all the nuclei (solid circular particles).

To enter initials for a high score, the player uses the trackball to circle letters in the same fashion used during gameplay.

A screenshot of a clone called Tachyon was previewed in Atari 8-bit magazine ANALOG Computing, but the game was never completed.