Quantum does not come with a Thunderbolt cable. Unlike standard copper data cables, Thunderbolt cables have electronics in the each end of the cable. The cost required to include such a cable made by PreSonus is too high to make a cable that works as well as the original designers of the Thunderbolt technology (ie Apple and Intel).
Apple is the dominant authority for Thunderbolt products, Apple has the manufacturing power to keep the cost of these cables low. The Apple Thunderbolt 0.5M cable and 2.0M cable are available for sale directly from Apple as well as many electronics stores world-wide. Quantum is also compatible with the longer Optical Thunderbolt cables available from Corning with lengths up to 200 feet (60 meters).