Exact interferometers for the concurrence and residual 3-tangle
Hilary A. Carteret · arXiv (Cornell University) · 2003
In this paper we describe a set of circuits that can measure the concurrence of a two qubit density matrix without requiring the deliberate addition of noise. We then extend these methods to obtain a circuit to measure one type of three qubit entanglement for pure states, namely the 3-tangle.