As I could inderstand they got 1.4 kA with a 1cm2 switch. Scaling this to 1Ma would mean 714 cm2 of switch area. That is 26 by 26 cm. This would also reduce resistance to 1/714 ohm.
Ofcause this would need a laser pulse of 50MW/cm2 * 714 cm2 = 35GW.
You would of cause have to stack three to get the proper voltage.
I am not shure if this is feasable, but it is getting close to the right ballpark.
