What's the plural of quantum?

As in a number of the smallest de facto units of anything you can have in the universe?

Currently in the running in my mind:

• Quanta
• Quantums

Solution 1:

Merriam-Webster, Wiktionary, The American Heritage Dictionary of the English Language, and the Collins English Dictionary all list only quanta as the plural form. So if I wanted to be on the safe side, I'd recommend that over quantums. The usage stats from the British National Corpus and the Corpus of Contemporary American English look as follows:

         BNC   COCA

quanta    35     95
quantums   0      3

Google results are too skewed to be included, as Quanta seems to be a popular proper name.

Solution 2:

'Quanta' is usually used, but 'quantums' is also valid according to the Oxford English Dictionary.