[VLM]

Civilized behavior would imply private splitting of the cash, at least. I can't remember an example of that ever happening with any Nobel award in any field, although its probably happened. One of those things I'm not sure how to google for without getting 99% unrelated. If done completely privately there may be no public record of any sort...

[Steuard]

I've always had the impression that the cash is the least important part of a Nobel prize. Even if you're being purely mercenary about it, Nobel laureates can probably get paid speaking engagements whenever they want. But it's the prestige that really matters, and I suspect that for most scientists a share of the cash would be a poor substitute.

[ISL]

As a physicist: There are lots of good reasons to go into physics. Doing it for the money probably isn't one of them.