Author(s): Rathindra Nath Das and Takato Mori In quantum systems, purification can map mixed states into pure states and a nonunitary evolution into a unitary one by enlarging the Hilbert space. We establish a connection between the complexities of mixed quantum states and their purification, proposing new inequalities among these complexities.… [Phys. Rev. Lett. 136, 030201] Published Tue Jan 20, 2026