Direct method for measuring of purity, superfidelity, and subfidelity of photonic two-qubit mixed states
Direct method for measuring of purity, superfidelity, and subfidelity of photonic two-qubit mixed states
The Uhlmann-Jozsa fidelity (or, equivalently, the Bures distance) is a basic concept of quantum communication and quantum information, which however is very difficult to measure efficiently without recourse to quantum tomography. Here we propose a direct experimental method to estimate the fidelity between two unknown two-qubit mixed states via the …