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 from the pair is measured with a polarizer set at an angle slightly different from the one you chose. We then see how many of these pairs make it through the polarizers. This is repeated for the second angle you chose. By comparing the results for each set of angles we can check for quantum entanglement. Entanglement is verified when the number of pairs making it through 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 related (for example, always the same).
What else can you use a quantum network for? Share your ideas with us!
Quantum fortune
What is really happening here?
When you press the button, you ask the entangled photons whether they’re a particular polarization or not. Because they’re entangled, their answers are related, even though their answers are unknowable ahead of time (they are in superposition). Every time they answer, a bit is created. All the bits together are used to create a random number corresponding to a message.
What else can you use a quantum network for? Share your ideas with us!