Scott Aaronson has done some work regarding CTCs and quantum computers: http://www.scottaaronson.com/papers/ctc.pdf http://www.scottaaronson.com/papers/ctc.pdf

Scott Aaronson has done some work regarding CTCs and quantum computers: http://www.scottaaronson.com/papers/ctc.pdf http://www.scottaaronson.com/papers/ctc.pdf Apparently, in the presence of CTCs, quantum computers are no more powerful than classical ones.