A quantum dot the size of a virus, squeezed between mirrors, gives birth to two photons in a short flash of light. These photons fly out as a pair, and their polarizations, the directions of wave oscillation, are linked such that knowing one instantly tells you the other. This connection is called entanglement, and it's essential for quantum communication and computation.
The main enemy of this connection is the jittering of the crystal's atoms due to heat. It disrupts the alignment, like shaky hands making it hard to thread a needle. Scientists measured how strong the photon connection remains at different temperatures and settings. They used two methods for the calculation: one exact but slow, the other approximate but fast.
This means engineers can quickly find the best conditions for quantum dots without spending hours on exact calculations. And the dots themselves will become more reliable sources of entangled photons for future quantum networks.
A quantum dot is so small that about ten thousand of them could fit across a human hair.
In the series "Star Trek," quantum entanglement is used for instant subspace communication.