While being incredibly useful for high-capacity quantum communication, high-dimensional entanglement is notoriously hard to measure. Quantum state tomography of a high-dimensional system of even modest dimension can take up to days, and the best entanglement witnesses aren’t much better.
In a recent paper published in Nature Physics, we developed and demonstrated a new method for measuring high-dimensional entanglement that requires only two measurement settings to work, independent of how large your system may be! We used this technique (which we fondly call the Mubby Witness) to certify a record entanglement dimensionality, without making any assumptions on the state.
This work came out of an intense theory-experiment collaboration with our collaborators in Vienna and Brno. From outdoor debates in Sunny Benasque to rapid back-and-forths between the lab and the blackboard, this project couldn’t have been more fun. Stay tuned for Mubby 2.0!
For coverage of this work in the popular media, please check out our media coverage page.