There's a lot of what's, where's etc. for anyone to give an informed opinion, however, physics is a good degree to have and with a DD who has graduated with a physics degree there are plenty of opportunities for her.
Obviously your DC may be absolutely sure of his / her decision but...
Seek advice and information from the universities your DC is interested in and from DC's teachers. It may
be worth considering a straight physics degree (3 or 4 yr) and then
post graduate study in a field that is of interest, and importantly more specific to DC's career or research ambitions.
3 or 4 years of degree level physics can enlighten a student to the many opportunities that they may not have even thought possible before they embarked on university level study.
Having a straight physics degree will not be a barrier to a student who wants to enter the field of quantum / nuclear physics afterwards.
Think about keeping his / her options open for as long as possible. Quite a few courses run yrs 1 and 2 the same and specialise in Y3 so maybe this is something to ask about.