Author here - ya "binary vectors" means quantizing to one bit per dimension. Normally it would be 4 * dimensions bytes of space per vector (where 4=sizeof(float)). Some embedding models, like nomic v1.5[0] and mixedbread's new model[1] are specifically trained to retain quality after binary quantization. Not all models do tho, so results may vary. I think in general for really large vectors, like OpenAI's large embeddings model with 3072 dimensions, it kindof works, even if they didn't specifically train for it.
Thank you! As you keep posting your progress, and I hope you do, adding these references would probably help warding off crusty fuddy-duddys like me (or at least give them more to research either way) ;)
[0] https://twitter.com/nomic_ai/status/1769837800793243687
[1] https://www.mixedbread.ai/blog/binary-mrl