New material exhibits bizarre 720 degree rotation property, which could be ideal for spintronics
Imagine a ball with a star on one side of it. You spin it around once and you will see that same star (a particular face of the ball). Most objects exhibit this property -- they must be rotated 360Â° to show the same face. Now imagine if you rotated the ball once, but still didn't see the star. You wonder what's going on and you rotate it a full rotation again and the star appears. This kind of 720Â° rotation to return to a face has never been observed on a macroscopic or microscopic scale -- until now.
Researchers at Princeton University, along with a team of esteemed researchers from around the globe have created a material in which electrons move in a strange dance that involves the bizarre, never-before-seen 720Â° rotation to return to a face. The new behavior is not only incredibly unusual, but it could open up new possibilities in quantum computing, a burgeoning branch of computers that seeks to exploit quantum effects on electrons, including their spin.
Zahid Hasan, an assistant professor of physics at Princeton and leader of the team, states, "We believe this discovery is not only an advancement in the fundamental physics of quantum systems but also could lead to significant advances in electronics, computing and information science."
Electrons have a charge, but they also have rotational properties. When electrons rotate, they create tiny poles of charge, making them behave like a nanoscopic bar magnet, something first observed by British physicist Paul Dirac.
The new behavior was first predicted by theorists at Princeton, the University of Pennsylvania, and the University of California-Berkeley. The key to it occurring was to create a material in which electrons spun at extremely high speeds and create a means to observe the behavior.
The researchers first developed new methods to use X-rays to observe the electron spin and take pictures of it. They then devised a material in which the electrons were spinning at an extremely high speed -- a carefully grown crystal of bismuth-laced antimony, which belongs to a class of materials known as "topological quantum spin Hall insulators."
Once the researchers began taking images, they were able to confirm that the electrons on the crystal's surface had to complete a 720Â° rotation in order to return to the same face, which faced outward, perpendicular the crystal surface.
Philip Anderson, a Princeton professor and recipient of the 1997 Nobel Prize in physics lauded the work, stating, "As a technical achievement, or a series of physics achievements alone, it is pretty spectacular."
Thomas Rieker, program director for the National Science Foundation's Materials Research Science and Engineering Centers, also cheered the discovery, both for the new techniques developed and the unique phenomena imaged. He says, "This discovery has the potential to transform electronics, data storage and computing. The spin-sensitive measurement techniques developed here may shed light on other important fundamental questions in condensed matter physics such as the origin of high-temperature superconductivity."
Professor Hasan says he believes that the phenomenon, like many strange quantum phenomena, can be exploited to create new kinds of quantum computers. He states, "This quantum weirdness -- a coordinated twist in the spin of electrons even though there is no magnetic field around -- is what we've been searching for by fine tuning our experiments over the last few years. It's a very fundamental piece of new physics -- it goes beyond what you would typically learn in a quantum physics textbook. In principle, you can use this new quantum dance of electrons to construct a very bizarre electronic circuit."
The unique spin could allow more information to be stored on an electron, which can already store more information in its quantum properties than in a simple on/off electrical circuit. States David Hsieh, a graduate student in Princeton's Department of Physics and key researcher on the project, "We can use this new quantum property of spinning particles to make computers that can store much more information and can have the capacity to perform computations much faster than present-day machines."
The researchers look to explore creating such machines possibly in the near future. They also are excited about applying their imaging method to discover new information about superconductors, magnets, and other electromagnetic phenomena.
The work was funded by the National Science Foundation, the U.S. Department of Energy, and Princeton University. It is reported in the journal Science.
This stuff blows my mind. How can something spin 720 before we see the same side again??? Quantum computers are going to be amazing demonstrations of crazy physics.