When light and atoms share a common vibe (VIDEO)
Caption
1. A laser generates a very short pulse of light 2. A fraction of this pulse is sent to a nonlinear device to change its color 3. The two laser pulses overlap on the same path again, creating a "write & read" pair of pulses. 4. Each pair is split into a short and a long path, 5. yielding an "early" and a "late" time slot, overlapping once again 6. Inside the diamond, during the "early" time slot, one photon from the "write" pulse may generate a vibration, while one photon from the "read" pulse converts the vibration back into light. 7. The same sequence may also happen during the "late" slot. But in this experiment, the scientists made sure that only one vibration is excited in total (in both early and late time slots). 8. By overlapping the photons in time again it becomes impossible to discriminate the early vs. late moment of the vibration. The vibration is now in a quantum superposition of early and late time. 9. In the detection apparatus, "write" and "read" photons are separated according to their different colors, and analyzed with single-photon counters to reveal their entanglement.
Credit
Santiago Tarrago Velez (EPFL)
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