In regard to the article by Brukner and Zeilinger:
"...interference fringes arise if and only if there is no possibility, not even in principle, to determine which path the particle took. And, most importantly, it is not relevant whether or not we care to take note of that information [i.e. path information?]. All that is necessary is whether or not the information is present somewhere in the universe. Only if such information is not present do interference fringes occur.
Indeed, the most interesting situations arise if the path information is present at some point in time, but deleted or erased in an irrevocable way later on. Then, as soon as that information is irrevocably deleted, the interference fringes can occur again." [Č. Brukner & A. Zeilinger, Quantum Physics as a Science of Information, in 'Quo Vadis Quantum Mechanics?', edited by A. Elitzur, S. Dolev, N. Kolenda, (Springer, 2005), p48]
This is an example of the kind of muddied thinking that can happen when information is objectified. The first statement is correct, although I'm not sure what "even in principle" can actually mean. The wording that betrays the inbuilt assumption regarding information is "deleted or erased". This type of thought would never occur in classical physics (which existed before computers). Image trying to delete the "path information" of a planet! What 'path information' must mean to be physically real is some observable physical trace or record resulting from the changing location of an object. An observable causal effect of some sort--the wake of a boat, for example. In terms of a planet, it might be an influence on the paths of other planets. Or, it could be a series of observations of apparent position, from which orbital position is calculated on the basis of (Newtonian) theory--in both cases in regard to some (artificial) reference frame. What would it mean to "delete" or "erase" such information? Does it mean to erase the path itself, the influences it had, or the human record of it? In the computer age, we are used to deleting information from files. We are not obliged to think about the correlated physical changes occurring in the computer hardware, the physical "path" of that information.
It is a mystery to me what the last statement can mean. If information means causal effects (rather than stored bits), even if it were somehow possible to undo these effects that have already occurred, this would not rewind time and undo the path that was actually taken by a given particle. We can change the circumstance for future particles (by opening of closing the slit), but this has nothing to do with information, unless it is the information about the state of the slit.