Chuck Bednar for redOrbit.com – Your Universe Online
The amazing field of quantum computing makes it possible for developers to break records for data processing, improve cyber security and create improved radar, space and aircraft system, but before that can happen, atoms need to be held and read without disappearing.
Now, researchers from the Niels Bohr Institute at the University of Copenhagen have developed a method that used a trap to capture atoms along an ultra-thin glass fiber, where those atoms can be controlled. Their results have been published in the journal Physical Review Letters.
The research was conducted in the Institute’s quantum optics laboratory, an underground facility that is located in an area where it will not be affected by vibrations from motor vehicle traffic. In this laboratory, the researchers conducted ultrasensitive experiments with quantum optics.
“We have an ultra-thin glass fiber with a diameter of half a micrometer (a hundred times smaller than a strand of hair),” explained Jürgen Appel, an associate professor in the Quantop research group at the Niels Bohr Institute. Cesium atoms are captured along this glass fiber, cooled down to almost absolute zero (100 micro Kelvin or negative 273 degrees Celsius) and held there.
When light is transmitted through the glass fiber threat, it will move along the surface because the fiber is thinner than the light’s wavelength, the researchers explained. As a result, strong interactions take place between the light and the atoms secured above the surface of the fiber.
“We have developed a method where we can measure the number of atoms,” Appel said. “We send two laser beams with different frequencies through the glass fiber. If there were no atoms on the fiber, the speed of light would be the same for both light beams.”
“However, the atoms affect the two frequencies differently and by measuring the difference in the speed of light for the two light beams on each side of the atoms’ absorption lines, you can measure the number of atoms along the fiber,” he added. “We have shown that we can hold 2,500 atoms with an uncertainty of just eight atoms.”
The study authors said that the results are “fantastic,” and said that without this technique, a researcher would have to use resonant light (or light that is absorbed by the atoms). They would then scatter photons, which would force atoms out of the trap. The new method allows them to measure and control the atoms so that just 14 percent are ejected from the trap and lost.
“Our resolution is only limited by the natural quantum noise (the laser light’s own minimal fluctuations) so our method could be used for so-called entangled states of atoms along the fiber,” Appel concluded. “Such an entangled system with strongly interacting atoms and light is of great interest for future quantum computer networks.”
According to Michael Schirber of the American Physical Society (APS), this minimally invasive technique can control the number of atoms with a degree of uncertainty that is nearly a factor of 10 less than other methods. Atoms trapped in optical lattices like this could be used to help create extremely precise atomic clocks and quantum computers, he added.
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