The Quantum Entanglement Device, often abbreviated to QED, also called the Richtofen Device by its inventor Edward Richtofen, is a secondary tactical grenade appearing on the Zombie map Moon.
When thrown, the QED is capable of creating many different outcomes. Upon toss, the player will spin the handle on the bottom once, and push it in. It can either "curse" or "bless" the player, with outcomes such as extra weapons, extra perks, more enemies, or a reset of points.
The Quantum Entanglement Device can only be obtained through the Mystery Box and takes up the player's secondary tactical grenade slot. It is one of two tactical Grenades on Moon, the other being the Gersh Device. The player cannot possess both; if the player attempts to take the Gersh Devices, any remaining QEDs will be swapped and vice versa.
The effect of the grenade is completely random, except in an instance where it is used against an Astronaut Zombie; if a QED goes off near one, it will always create an explosion capable of killing zombies.
If the Zombies run over a "blessing" given by the QED, the players lose it with no way to recover the power up. If the Zombies run over a "curse", however, then the negative effect will still happen as if a player grabbed the power up.
It is possible to obtain a QED from a random weapon drop.
Throwing a QED at the excavator will deactivate it in rare circumstances.