4 ms·
https://pubmed.ncbi.nlm.nih.gov/10917523/ https://pubmed.ncbi.nlm.nih.gov/10917523/ The nature paper is probably a better link thank optics.org, this is a few y
by whateveryoua381 5y ago
https://pubmed.ncbi.nlm.nih.gov/10917523/ https://pubmed.ncbi.nlm.nih.gov/10917523/
The nature paper is probably a better link thank optics.org, this is a few years before the demonstration, however it has the same claim of 300x speed of super-luminal (faster than light) group velocity.