Quantification of multi-dimensional photonic entanglement stored in a quantum memory based on sparse data
Author(s): A. Tiranov, S. Designolle, E. Z. Cruzeiro, J. Lavoie, N. Brunner, M. Afzelius, M. Huber, N. Gisin
Link: Link to publication
Multi-dimensional entanglement offers interesting possibilities in quantum information e.g. quantum cryptography. Here we report the characterization of two-photon multi-dimensional energy-time entanglement between many temporal modes, after one photon has been stored in a solid-state quantum memory. We develop a method for entanglement quantification which makes use of only very sparse data, namely coincidences in the time-of-arrival basis and coherences between two neighboring temporal modes. This allows us to certify that the quantum state after storage in our experiment features at least 1.18 ebits of entanglement of formation. The theoretical methods we develop can be readily extended to a wide range of experimental platforms, while our experimental results demonstrate the suitability of energy-time multi-dimensional entanglement for a quantum repeater architecture.