A measurement scheme for purity based on two two-body gates
arXiv:1201.2736 · doi:10.1103/PhysRevA.85.042316
Abstract
A scheme for measuring the purity of a quantum system with a finite number of levels is presented. The method makes use of two square root of SWAP gates and only hinges on measurements performed on a reference system, prepared in a certain pure state and coupled with the target system. Neither tomographic methods, with the complete reconstruction of the state, nor interferometric setups is needed.
7pages, 1figure