The D-CTC condition in quantum field theory

Abstract: A condition proposed by David Deutsch to describe analogues of processes in the presence of closed timelike curves (D-CTC condition) in bipartite quantum systems is investigated within the framework of local relativistic quantum field theory. The main result is that in relativistic quantum field theory on spacetimes where closed timelike curves are absent, the D-CTC condition can nevertheless be fulfilled to arbitrary precision, under very general, model-independent conditions. Therefore, the D-CTC condition should not be taken as characteristic for quantum processes in the presence of closed timelike curves in the sense of general relativity. This report is a very condensed extract of the publication J. Tolksdorf, R. Verch, Commun. Math. Phys. 357 (2018) 319-351. A new result showing that the D-CTC condition can be approximately fulfilled by entangled states is also presented.