How viable or how far away would deployment of such an engine be from now? Commenter Casey makes an interesting point whether this is viable ot not:

This engine isn’t fast. 50 micronewtons is nothing. I mean that, it’s almost literally nothing. 50 micronewtons could barely propel a fly’s mass to Earth’s escape velocity, even without drag…and that’s assuming only the fly, not the weight of the engine, is taken into account. Now, yes, once you get into orbit you don’t have to worry about these things, this engine will not accelerate anything in a timely fashion. Now, you might say, “But, Casey! Technology will evolve and we could put a bigass version of this engine!” Sure, absolutely…but you’ll need a power source. Solar panels or a nuclear reactor would be the way to go…you’ll need several reactors to even make an insignificant amount of thrust (probably not even noticeable to the humans aboard the craft) or a truly incredible amount of solar panels – I’m talking miles wide in both width and length…then you have all this extra weight so you need even more thrust. Don’t forget that this craft has to be somehow deployed into orbit…

As with many prototypes and theory tests, this one is clearly early on.  We hope you enjoy the videos!