1 Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Spain 2 Faculty of Informatics, Università della Svizzera italiana, Via G. Buffi 13, 6900 Lugano, Switzerland 3 Facoltà indipendente di Gandria, Lunga scala, 6978 Gandria, Switzerland 4 Vienna Center for Quantum Science and Technology (VCQ), Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria 5 Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna, Austria 6 Group of Applied Physics, University of Geneva, 1211 Geneva 4, Switzerland 7 ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels, Barcelona, Spain

We derive a framework for quantifying entanglement in multipartite and high dimensional systems using only correlations in two unbiased bases. We furthermore develop such bounds in cases where the second basis is not characterized beyond being unbiased, thus enabling entanglement quantification with minimal assumptions. Furthermore, we show that it is feasible to experimentally implement our method with readily available equipment and even conservative estimates of physical parameters.

High dimensional entanglement naturally created in down conversion processes carries great potential for improving quantum communication tasks. A central challenge is developing feasible methods for its experimental certification that scale well in system dimension. Here, we make progress on this task by developing a general method for quantifying high-dimensional entanglement using correlations in only two local unbiased bases. Surprisingly, in the ideal case all entanglement can be certified with only two measurements, even if detailed phase relations between the measurements are not known. This enables an experimental proposal using only a camera and a lens as measurement devices, which we show could realistically compete with the currently highest certified entanglement in more complicated setups.

@article{Erker2017quantifyinghigh, doi = {10.22331/q-2017-07-28-22}, url = {https://doi.org/10.22331/q-2017-07-28-22}, title = {Quantifying high dimensional entanglement with two mutually unbiased bases}, author = {Erker, Paul and Krenn, Mario and Huber, Marcus}, journal = {{Quantum}}, issn = {2521-327X}, publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}}, volume = {1}, pages = {22}, month = jul, year = {2017} }

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This Paper is published in Quantum under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Copyright remains with the original copyright holders such as the authors or their institutions.