spontaneous parametric down-conversion fiber coupler quantum dot Hong–Ou–Mandel effect particle antiparticle electron positron quantum wave functions Hardy's interferometer Bell's theorem atomic cascades polarization methods subatomic particle particles photons
Entanglement is usually created by direct interactions between subatomic particles. These interactions can take numerous forms. One of the most commonly used methods is spontaneous parametric down-conversion to generate a pair of photons entangled in polarization. Other methods include the use of a fiber coupler to confine and mix photons, photons emitted from decay cascade of the bi-exciton in a quantum dot, the use of the Hong–Ou–Mandel effect, etc. Quantum entanglement of a particle and its antiparticle, such as an electron and a positron, can be created by partial overlap of the corresponding quantum wave functions in Hardy's interferometer.
In the earliest tests of Bell's theorem, the entangled particles were generated using atomic cascades.
