Unlike heavier-than-air flight, this isn't in the category of a technical problem yet to be solved. It's more along the lines of not being able to reach temperatures below absolute zero.

By all understanding, FTL travel between two points in space appears to be impossible even when attempting to bypass direct FTL travel through that space via wormholes or Alcubierre drives. Alcubierre himself has doubts regarding his drive, indicating it has the potential to violate causality, a point supported by Prof. Allen Everett. Such violation is anathema to most cosmologists and physicists.

In other words, the speed of light is set not by light itself, but by causality. It is deeply fundamental to the nature of the universe. Even were FTL travel possible, it'd only be through phenomena such as multiple forking universal timelines, that is, one way trips out of "our" universe.

Meanwhile, beyond this somewhat dated paper (PDF) refuting White and Juday's claims, I couldn't find any refereed papers or sources for their interferometer. Have you one to provide?