@article{bibcite_14623, author = {Charles Dunkl and Piotr Gawron and J.A. Holbrook and Jaroslaw Miszczak and Zbigniew Pucha{\l}a and Karol {\.Z}yczkowski}, title = {Numerical shadow and geometry of quantum states}, abstract = {The totality of normalised density matrices of order N forms a convex set Q\_N in R^(N^2-1). Working with the flat geometry induced by the Hilbert-Schmidt distance we consider images of orthogonal projections of Q\_N onto a two-plane and show that they are similar to the numerical ranges of matrices of order N. For a matrix A of a order N one defines its numerical shadow as a probability distribution supported on its numerical range W(A), induced by the unitarily invariant Fubini-Study measure on the complex projective manifold CP^(N-1). We define generalized, mixed-states shadows of A and demonstrate their usefulness to analyse the structure of the set of quantum states and unitary dynamics therein.}, year = {2011}, journal = {J. Phys. A: Math. Theor.}, volume = {44}, number = {33}, pages = {335301}, issn = {1751-8113}, note = {arXiv:1104.2760 IF=1.641(2010);}, language = {eng}, }