Time reversal of open quantum systems by linear operations?

by Erik Aurell (KTH)

Thursday 21 Oct 2021, 13:00 → 14:00 Europe/Stockholm

AlbaNova C4:3059 - Café Planck (AlbaNova Main Building)

A general evolution of a quantum system is described by a completely positive trace-preserving (CPTP) map. A time reversal of one and all evolutions should then be an involution of the set of all CPTP maps. A physical time reversal should also reduce to standard quantum mechanical time inversion when acting on unitary maps, i.e. on a closed system.

I will consider the question if such universal time reversal can be implemented as a linear involution. This could, at least in some views, then be considered a universal time-reversal machine, which would in principle exist.

I will show that the answer is negative if we consider the more general class of completely positive trace non-increasing maps (aka "quantum operations"), and will describe our so far unsuccessful attempts to show the corresponding result for CPTP maps.

The talk is based on is joint work with Giulio Chiribella and Karol Życzkowski, available as Physical Review Research 3 (3), 033028 (2021).