[maxwellsdeamons]

1.25 millions doesn’t even buy you the laser to cool the atom gas. It’s for sure interesting, but to put this on a train, we will have to solve a few more questions. like for example, how do you operate an optical table on a bumpy metro.

[bluGill]

Those are the important questions that the people who need this need answered. Trains have better options than this, but there are some applications that don't and trains are an easy place to test whatever you are trying, if it works on a train you can then build the real thing (which is often an airplane or missile - with power an weight limitations that don't apply to trains)