James M. McCracken

Negative Quantum Channels: An Introduction to Quantum Maps that are Not Completely Positive - Synthesis Lectures on Quantum Computing James M. McCracken

Provides a brief introduction to negative quantum channels - linear, trace-preserving (and consistent) quantum maps that are not completely positive. The flat and sharp operators are introduced and explained. Complete positivity is presented as a mathematical property, but it is argued that complete positivity is not a physical requirement of all quantum operations.