Direct measurement of non-linear properties of bipartite quantum states
Abstract
Non-linear properties of quantum states, such as entropy or entanglement, quantify important physical resources and are frequently used in quantum information science. They are usually calculated from a full description of a quantum state, even though they depend only on a small number parameters that specify the state. Here we extract a non-local and a non-linear quantity, namely the Renyi entropy, from local measurements on two pairs of polarization entangled photons. We also introduce a "phase marking" technique which allows to select uncorrupted outcomes even with non-deterministic sources of entangled photons. We use our experimental data to demonstrate the violation of entropic inequalities. They are examples of a non-linear entanglement witnesses and their power exceeds all linear tests for quantum entanglement based on all possible Bell-CHSH inequalities.
Keywords
Cite
@article{arxiv.quant-ph/0511187,
title = {Direct measurement of non-linear properties of bipartite quantum states},
author = {Fabio Antonio Bovino and Giuseppe Castagnoli and Artur Ekert and Pawel Horodecki and Carolina Moura Alves and Alexander Vladimir Sergienko},
journal= {arXiv preprint arXiv:quant-ph/0511187},
year = {2009}
}
Comments
To appear on PRL with minor changes