Bose-Einstein condensate (BEC): This state of matter can be credited to both Indian physicist Satyendra Nath Bose and Albert Einstein.
Borrowing from Bose's math, Einstein proposed the existence of this new, super cool (literally) state of matter in 1924. It was later experimentally verified in 1995.
Superconductivity: Unlike some of the more theoretical states of matter, you might be lucky enough to get a demonstration of superconducting materials at your local college physics lab. These materials are supercooled and as a result, offer zero resistance to electricity (meaning they're an extremely good conductor.)
Crystals like diamonds are prized for their repeating, geometric patterns and don't change much over time.
Time crystals change in both space and time, meaning the entire crystal changes from moment to moment. Controlling these crystals could be the key to mastering "warm" quantum computing above absolute zero.