Revisiting integer factorization using closed timelike curves

Closed timelike curves are relativistically valid objects allowing time travel to the past. Treating them as computational objects opens the door to a wide range of results which cannot be achieved using non-relativistic quantum mechanics. Recently, research in classical and quantum computation has focused on effectively harnessing the power of these curves. In particular, Brun (Found Phys Lett 16:245–253, 2003) has shown that CTCs can be utilized to efficiently solve problems like factoring and quantified satisfiability problem. In this paper, we find a flaw in Brun’s algorithm and propose a modified algorithm to circumvent the flaw.