Aharon Brodutch
  • Member for 3 years, 9 months
  • Last seen more than a month ago
Only assuming the universe evolves according to a positive trace-preserving map, is there a proof that all subsystem evolution must be CPTP?
1 votes

There are two possible answers. Let's say the universe evolves from $t=0$ to $t_f$ then the unitary evolution $U$ from $0$ to $t_f$ induces a CP evolution on the subsystem. To see this, note that ...

View answer
Is acting with a positive map on a state not part of a larger system allowed?
0 votes

The situation of non-completely positive maps (or more generally non-linear maps) is controversial partly due to the precise definition of how you should construct the map. But it is easy to come up ...

View answer