EntityQ2627013· pop 7· linked from 39 articlespositive elementSign in to saveself-adjoint (or Hermitian) element A of a C*-algebra A is called positive if its spectrum σ (A) consists of non-negative real numbersConnectionsquantum stateEntityquantum mechanicsEntitydensity matrixEntitymathematicsEntityphysicsEntityInternational Standard Book NumberEntityangleEntitylinear algebraEntitysetEntityHilbert spaceEntityfunctional analysisEntitylinear mapEntitydomain of a functionEntityunit vectorEntityCauchy–Schwarz inequalityEntitymonotonic functionEntityinner product spaceEntitySpringer Science+Business MediaEntitypartially ordered setEntitylinear spanEntityCategoriesOperator theory