just short of 300 million metres per second.
By adjusting the frequency of the laser beams to match those of the energy levels

Because of the fast group velocity, the leading edge of the pulse appears to leave the caesium-filled chamber 62 billionths of a second before it arrives.

it would take a lot of bouncing through a container to achieve a lot of time travel^ of the light.

hmmm...a mirrowed container?

a mirrowed spiraled tube...gone where did the light go.

oh wait... there it is...I forgot we had to wait till we caught up with time!!!!

3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.