>>> fired a few photons into a vacuum chamber with a cloud of extremely cold rubidium atoms
So it works only in a (sorta) vacuum in the presence of rubidium atoms - so it’s not really a vacuum.
No mention of being able to use it as a weapon.
So it’s an incredibly complicated, impractical flashlight that more than likely requires a huge and probably immobile power supply.
meh. Not a light sabre.