To place the development of cryogenic rocket engines in its proper historical context, I thought you might want to know that NASA developed the world's first cryo engine in 1961 and China flight-tested her first cryo engine in 1984 (i.e. 26 years ago).
Cryogenic rocket engine - Wikipedia, the free encyclopedia
"The first operational cryogenic rocket engine was the 1961 NASA design the RL-10 LOX LH2 rocket engine, which was used in the Saturn 1 rocket employed in the early stages of the Apollo moon landing program."
YF-73 - Wikipedia, the free encyclopedia
"The YF-73 is China's first successful, cryogenic, gimballed engine, using liquid hydrogen (LH2) fuel and liquid oxygen (LOX) oxidizer. It was developed in the early 1980s and first flight was in 1984."