[xsamgreen]

FHE is undergoing standardization right now. The leading algorithm candidates are based on lattice crypto which is currently quantum-safe: https://homomorphicencryption.org/

Here are some mature and actively-developed HE libraries:

https://github.com/homenc/HElib (By IBM, employed the inventor of FHE)

https://github.com/Microsoft/SEAL (Best tutorials)

https://palisade-crypto.org/software-library (High-quality codebase)

https://github.com/tfhe/tfhe (Fast boolean logic, used by Cingulata)

Good introductory material is hard to come by, but I like the first half of this talk: https://simons.berkeley.edu/talks/intro-fhe-and-tfhe