Behind the Scenes

Verify quantum link
What is really happening here?

Many pairs of entangled photons are created in our lab on campus. One photon from each pair is sent through fiber-optic cable to the library, where its polarization is measured with a polarizer set at the angle you chose. Back at the lab, the other photon is measured with a polarizer set an angle slightly different from the one you chose. This is repeated for the second angle you chose. By comparing the results for each set of angles, the degree of correlation the photons can be determined. For quantum entanglement, the degree of correlation exceeds what is possible classically. This is because in quantum entanglement, the polarizations of the photons are undecided before measurement (the photons are in superpositions of polarizations), and yet at the time of measurement the polarizations are always correlated (e.g. always the same).

What else can you use a quantum network for? Share your ideas with us!