Yes, it's theoretically possible. It's actually already been done in hard science fiction - see the sequel to H.G. Well's The Time Machine, The Time Ships. The book espouses the Many-worlds interpretation of quantum mechanics. I don't have the book on hand anymore, but the gist is that the time traveler goes back into the future where he discovers he's entered a different future than the one he originally went to. He meets a Morlock named Nebogipfel, who explains that because he publicized his original experience, he had changed the future. The original future is still there, but it's now in a "different universe".
The question now is whether the time traveler in this universe can communicate with the time traveler in the original universe. Nebogipfel asks the time traveler if he thought it's possible, and the time traveler said "no". Nebogipfel then says that this is true only if quantum mechanics is linear. If there are small non-linearities, then communication becomes possible. If information can be passed from one universe to the next, then presumably physical objects can also be passed. In fact in the finale of the book, a super-species known as the "Constructors" send the time traveler back to the original future by turning back time to the Big Bang (see the synopsis on Wikipedia).
Mind you, I tried asking for the math behind this on the Physics SE, but nobody seems to have seen it (the question has since been deleted). Still, it's a hard science fiction book which is supposed to be scientifically accurate. Therefore the math presumably must exist. Caveat: as far as I know, there is no experimental evidence that quantum mechanics is nonlinear. However, you can always postulate nonlinearity at a level below the experimental threshold.
tl, dr: it's possible if you 1) accept the Many-worlds interpretation of quantum mechanics and 2) assume quantum mechanics is slightly non-linear.