Quantum torpedo

The quantum torpedo was a weapon developed by Starfleet in the 2370s as a replacement for the standard photon torpedo. Development began in the late 2360s, and started to enter use in the early 2370s. (DS9 episode: "Defiant", ST movie: Star Trek: First Contact)

The quantum torpedo utilizes a Zero-Point Reaction to create a 50+ isoton explosion. It was created as one of the weapons system designed to fight the Borg. Indeed, quantum torpedoes were widely used by the Federation fleet when the Borg launched a second assault in early 2373. There are two types of torpedo tubes created for this weapon: The pulse fire tube (1 torp/second) and the rapid fire tube (which can fire at a rate of 4/second) (DS9 reference: Technical Manual, ST movie: Star Trek: First Contact)

By 2376, Deep Space 9 was armed with quantum torpedoes. (DS9 novel: Avatar)

After their successful first test on the Defiant, quantum torpedoes were implemented throughout the Federation fleet. Defiant, Sovereign, Luna, Vesta, Akira and Achilles class starships included quantum torpedoes in their arsenal. Quantum torpedoes were later given to the Klingon Empire and were implemented on their Chancellor-class Vessels.

In the alternate reality created by the temporal displacement of the Narada Starfleet had begun using quantum torpedoes as early as the 2250s. While not yet in use as standard armaments they could be deployed on Arbiter, Constitution-class, Defender-class, Guardian-class, and Interceptor-class starships. (TOS video game: D-A-C)