2 minutes to 20% the speed of light ?
We can’t even think of metals that would tolerate this sort of explosive technology. What he’s talking about is a sort of lighter-than-air (Fog) that can contain several hydrogen bombs worth of directed energy.
And I fail to see that sort of power emitted from anything either. Remember that with lasers the power at the receiving end is matched exactly as it is at the source. Heat included.
While I’m not a specific quantum-propulsion scientist - I have read just about every take on this “solar sail” thing since the 70s. I have yet to see why people are still sitting at that table, discussing it.
None of this stuff can withstand a particle of dust hitting the sail.