Physicists developed a new technique that allowed them to successfully entangle 3,000 atoms using nothing more than a single photon.
The study represents the largest number of particles that have ever been mutually entangled, and could lead to breakthroughs such as ultra-precise atomic clocks, Massachusetts Institute of Technology (MIT) reported.
"You can make the argument that a single photon cannot possibly change the state of 3,000 atoms, but this one photon does - it builds up correlations that you didn't have before," said Vladan Vuletic, the Lester Wolfe Professor in MIT's Department of Physics, and the paper's senior author. "We have basically opened up a new class of entangled states we can make, but there are many more new classes to be explored."
"Entanglement" is a phenomenon is which two or more particles simultaneously change in the same way (such as in which direction they spin) no matter how far apart they are. Albert Einstein famously dismissed entanglement as "spooky action at a distance," is described by the laws of quantum mechanics as opposed to physics.
Researchers have been on the hunt for methods that allow them to entangle large quantities of atoms, which could lead to the development of quantum computers and precise atomic clocks. Today's atomic clocks keep steady time in the same manner as a pendulum through natural oscillations within a cloud of trapped atoms. A laser beam within these clocks can detect the vibration of atoms in a way that reveals the length of a second.
"Today's clocks are really amazing," Vuletic said. "They would be less than a minute off if they ran since the Big Bang - that's the stability of the best clocks that exist today. We're hoping to get even further."
Modern atomic clocks' precision is "proportional to the square root of the number of atoms." This means a clock with nine times more atoms would be three times as accurate, so the larger the number entangled particles, the more accurate the clock.
In the past, the record for most entangled atoms was at only 100, but a weak laser light with pulses containing a single photon allowed the researchers to entangle and impressive 3,000.
"The technique significantly broadens the options for generating and operating on non-classical, entangled states of atomic ensembles," said Eugene Polzik, a professor of quantum optics at the Niels Bohr Institute who was not involved in the research. "As such, it can be useful for clocks, quantum sensing of magnetic fields, and quantum communication."
The findings were published in a recent edition of the journal Nature.
