Hmmm …. I'm not so sure that these kinds of measurements are saying anything one way or the other, about MWI or Copenhagen .. specifically (??)
The trick seems to be that they are not doing direct, hard measurements which result in the wavefunction collapsing completely. (This is the beauty of the 'weak' measurement technique). For example, they are only inducing a very small amount of polarisation (10 degrees), and because this is so small, the system, supposedly, isn't 'greatly' disturbed.
With the Uncertainty principle, measuring a quantum system without effectively destroying it
before the wavefunction is fully known, has been previously deemed virtually impossible. But now, they have directly measured the wavefunction of identical single photons for the first time
without destroying the wavefunction.
If this is the case, (ie: no wavefunctions have been destroyed), then the measurement has been done to the system in a sort of quasi-real state (sort of 'inferred' reality). They talk of real and imaginary components comprising the end result.
If no reality has been definitively established (by a destructive measurement), then can we really say that has this 'branching' has occurred (as per the MWI) thereby adding support to this interpretation ?? Similarly, the Copenhagen interpretation seems to be avoided also (for the same reason) ??
It seems to me that their technique dances around both MWI and Copenhagen ??
I'm open to correction here …
Interesting.
Cheers