Debbie Leung: Computational and Cryptanalytic consequences of time travel

Debbie Leung, Institute for Quantum Computing

We focus on two particular models of closed time like curves.

The first is Deutsch's 1991 mixed-state-fixed-point model which
abolishes the grandfather paradox. The second is due to Bennett and
Schumacher, in which the grandfather paradox on certain initial states
is exploited as a putative physical mechanism for post-selection.

We discuss possible consequences of the existence of such closed
timelike curves on quantum information processing.

Joint work with Charles Bennett, Graeme Smith, and John Smolin from
IBM TJ Watson Research Center