An anti-matter drive was a type of engine that could produce massive amounts of power. It was used during the 67th century, and was becoming even more advanced in design by that time. The drive utilised a super-compact particle accelerator to form and contain anti-matter particles in order to produce heat energy which could, in turn, power an entire ship.
A medical ship called the Tsuranga possessed a somewhat outdated anti-matter drive, which the Doctor couldn't help but to admire. While explaining its function to Yasmin Khan, she referred to the drive as "the IPhone version of CERN" when Yaz pointed out that particle accelerators at her time were many kilometers wide, noting that technology was always getting smaller and cheaper. (TV: The Tsuranga Conundrum)