PORTLAND, Ore. -- Last week scientists reported that the neutron was not electrically neutral after all. Now, this week, neutrons are reported to enable images to be made of "spooky" quantum states where a binary "1" and a binary "0" can be simultaneously maintained. The researchers, led by the London Centre for Nanotechnology (LCN), showed the world's first images of quantum entanglement in the prestigious scientific publication, the Proceedings of the National Academy of Sciences (PNAS).
"We were following a hunch that this material might yield something important," said LCN scientist Des McMorrow. "But none of us were expecting to see such gigantic effects produced by quantum entanglement."
The team of international researchers produced images of the magnetic spins inherent in the electrons in the copper atoms of an organic antiferromagnetic material. By arranging four of these atomic scale bar magnets in the corners of a square lattice Heisenberg system, the researchers were able to use neutron magnetic scattering to image the four tiny bar magnets both when they were behaving classically and when they were entangled.
Antiferromagnetic materials, as opposed to ferromagnetic materials (ordinary magnets), self-organize the magnetic spins of their component atoms in alternating directions when cooled below their Neel temperature. For instance, in the classical square lattice imaged by the researchers here, the upper-left atom has spin up, while both its neighbors (upper right and lower left) have spins down. The neutron beam produced an image of this classical state, which revealed a nearly circular spot of magnetism.
However, when tiny bar magnets' quantum states were entangled, the image of their quantum states, as revealed by neutron magnetic scattering, was in the shape of a cross, showing that each corner would always have the opposite spin, signifying entanglement, even though they were representing both "up" and "down" spins simultaneously.
Now that neutron beams, which are produced by particle accelerators and nuclear reactors, have been demonstrated to be capable of imaging quantum entanglement, the researchers plan to develop instrumentation for imaging other examples of quantum states to assist in the construction of future quantum computers.
The team also plans to image high-temperature superconductors using neutron magnetic scattering, suspecting that the ability to conduct electricity without resistance is based on principles similar to those governing antiferromagnets.
Team members came from research centers around the world, including University College London, Technical University of Denmark (Roskilde), Ecole Polytechnique Federale de Lausanne (EPFL, Switzerland), Rutherford Appleton Laboratory (Chilton U.K.), University of Edinburgh (U.K.), Institut Laue-Langevin (Grenoble, France), Oxford University (U.K.), University of Bristol (U.K.) and Centre de recherche sur l'energie nuclaire (CEA, Grenoble, France).