Quantum Fisher Information for Density Matrices with Arbitrary Ranks
Jing Liu, Xiao-Xing Jing, Wei Zhong +1 more
We provide a new expression of the quantum Fisher information (QFI) for a general system. Utilizing this expression, the QFI for a non-full rank density matrix is only determined by its support. This expression can bring convenience for an infinite-dimensional density matrix with a finite support. Besides, a matrix representation of the QFI is also given.
arXiv:1312.6910•Communications in Theoretical Physics•Jan 1, 2014•127 citations