文摘
Extending Li and Poon's results on interpolation problems for matrices, we give characterizations of the existence of a completely positive linear map 桅cp between compact (or Schatten-p class) operators sending a particular operator A to another B . It is shown that such a map exists if a multiple of the numerical range of A contains the numerical range of B . Given two commutative families of compact (or Schatten-p class) operators {A伪} and {B伪}, we provide sufficient and necessary conditions to ensure that we can choose a completely positive interpolation 桅cp to preserve trace and/or approximate units such that 桅cp(A伪)=B伪 for all 伪.