Recall that a density operator is a non-negative operator on a Hilbert spacewith unit … See more

Kraus' theorem (named after Karl Kraus) characterizes completely positive maps, that model quantum operations between quantum states. Informally, the theorem ensures th… See more

For a non-relativistic quantum mechanical system, its time evolution is described by a one-parameter group of automorphisms {αt}t of Q. This can be narrowed to unitary transformat… See more

Quantum operations can be used to describe the process of quantum measurement. The presentation below describes measurement in terms of self-adjoint proj… See more

Shaji and Sudarshanargued in a Physical Review Letters paper that, upon close examination, complete positivity is not a requirement for a good representation of open quant… See more