Guest_Jim_* Posted March 30, 2015 Posted March 30, 2015 Atomic clocks are the most accurate clocks in the world, but even though they would have only lost a minute since the Big Bang, researchers are still pushing for still more accurate versions. One way to achieve that is to entangle the atoms used by the clock, but entangling more than just pairs of atoms is difficult. Researchers at MIT however have found that they can entangle some 3000 atoms at a time, with a single photon. Atomic clocks work by exploiting the fact that atoms will vibrate at a specific frequency, under the right circumstances. These vibrations are measured by firing a laser through a cloud of atoms. By adding more atoms to the cloud, the accuracy of the clock is increased, but normally the increase is related to the square root of the number of atoms. That is unless the atoms are entangled, and then the increase is directly proportional. What the MIT researchers did is fire a very weak laser beam through a cloud of atoms and watched the atoms' polarizations. They reasoned that any deviation to a photon's polarization is the result of it interacting with the atoms' spins, and the amount it changes depends on the number of atoms spinning in one direction or the other. Occasionally though the researchers detected a photon that had its polarization made perpendicular, which had to have been done by the ensemble of atoms, and by detecting that photon, the ensemble would enter a strong entangled state. While the researchers were looking for ways to improve atomic clocks, this research could have implications in other quantum systems, such as quantum communication and the sensing of magnetic fields. Source: MIT Share this post Link to post Share on other sites More sharing options...
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