Quantum Device Traps, Detects and Manipulates the Spin of Single ElectronsSeptember 28, 2007BUFFALO, N.Y. -- A novel device, developed by a team led by University at Buffalo engineers, simply and conveniently traps, detects and manipulates the single spin of an electron, overcoming some major obstacles that have prevented progress toward spintronics and spin-based quantum computing. Published online this week in Physical Review Letters, the research paper brings closer to reality electronic devices based on the use of single spins and their promise of low-power/high-performance computing. "The task of manipulating the spin of single electrons is a hugely daunting technological challenge that has the potential, if overcome, to open up new paradigms of nanoelectronics," said Jonathan P. Bird, Ph.D., professor of electrical engineering in the UB School of Engineering and Applied Sciences and principal investigator on the project. "In this paper, we demonstrate a novel approach that allows us to easily trap, manipulate and detect single-electron spins, in a scheme that has the potential to be scaled up in the future into dense, integrated circuits."
While several groups have recently reported the trapping of a single spin, they all have done so using quantum dots, nanoscale semiconductors that can only demonstrate spin trapping in extremely cold temperatures, below 1 degree Kelvin. The cooling of devices or computers to that temperature is not routinely achievable, Bird said, and it makes systems far more sensitive to interference. The UB group, by contrast, has trapped and detected spin at temperatures of about 20 degrees Kelvin, a level that Bird says should allow for the development of a viable technology, based on this approach. In addition, the system they developed requires relatively few logic gates, the components in semiconductors that control electron flow, making scalability to complex integrated circuits very feasible. The UB researchers achieved success through their innovative use of quantum point contacts: narrow, nanoscale constrictions that control the flow of electrical charge between two conducting regions of a semiconductor. "It was recently predicted that it should be possible to use these constrictions to trap single spins," said Bird. "In this paper, we provide evidence that such trapping can, indeed, be achieved with quantum point contacts and that it may also be manipulated electrically." The system they developed steers the electrical current in a semiconductor by selectively applying voltage to metallic gates that are fabricated on its surface. These gates have a nanoscale gap between them, Bird explained, and it is in this gap where the quantum point contact forms when voltage is applied to them. By varying the voltage applied to the gates, the width of this constriction can be squeezed continuously, until it eventually closes completely, he said. "As we increase the charge on the gates, this begins to close that gap," explained Bird, "allowing fewer and fewer electrons to pass through until eventually they all stop going through. As we squeeze off the channel, just before the gap closes completely, we can detect the trapping of the last electron in the channel and its spin." The trapping of spin in that instant is detected as a change in the electrical current flowing through the other half of the device, he explained. "One region of the device is sensitive to what happens in the other region," he said. Now that the UB researchers have trapped and detected single spin, the next step is to work on trapping and detecting two or more spins that can communicate with each other, a prerequisite for spintronics and quantum computing. Co-authors on the paper are Youngsoo Yoon, Ph.D., a UB doctoral student in electrical engineering; L. Mourokh of Queens College and the College of Staten Island of the City University of New York; T. Morimoto, N. Aoki and Y. Ochiai of Chiba University in Japan; and J. L. Reno of Sandia National Laboratories. The research was funded by the U.S. Department of Energy. Bird, who also has received funding from the UB Office of the Vice President for Research, was recruited to UB with a faculty recruitment grant from the New York State Office of Science, Technology and Academic Outreach (NYSTAR). The University at Buffalo is a premier research-intensive public university, the largest and most comprehensive campus in the State University of New York. UB's more than 28,000 students pursue their academic interests through more than 300 undergraduate, graduate and professional degree programs. Founded in 1846, the University at Buffalo is a member of the Association of American Universities. The University at Buffalo Science News and Science Current Events Tag Cloud This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size. Threatened Species Pheromones Cancer Gene Consumers Chromosome Acid Rain Phytophthora CPAP Prozac Irritable Bowel Syndrome Positron emission tomography HIV transmission Television Air Pollution Nitric Oxide Quantum Physics Antarctic Venus Cardiomyopathy Water Pycnogenol Enceladus Eating Disorder Dark Energy Invasive species
See More: Science News Tags | |||||||||||||||||||||
|
Related Quantum Current Events and Quantum News Articles NIST develops novel ion trap for sensing force and light Miniature devices for trapping ions (electrically charged atoms) are common components in atomic clocks and quantum computing research. Now, a novel ion trap geometry demonstrated at the National Institute of Standards and Technology (NIST) could usher in a new generation of applications because the device holds promise as a stylus for sensing very small forces or as an interface for efficient transfer of individual light particles for quantum communications. Researchers unite to distribute quantum keys Researchers from across Europe have united to build the largest quantum key distribution network ever built. Scientists create first working model of a 2-qubit electronic quantum processor A team led by Yale University researchers has successfully implemented simple algorithms using a quantum processor based on microwave solid-state technology--similar to that found in computers and cell phones. Scientists create first electronic quantum processor A team led by Yale University researchers has created the first rudimentary solid-state quantum processor, taking another step toward the ultimate dream of building a quantum computer. University of Oklahoma Researchers Discover Giant Rydberg Atom Molecules A group of University of Oklahoma researchers led by Dr. James P. Shaffer, Homer L. Dodge Department of Physics and Astronomy, have discovered giant Rydberg molecules with a bond as large as a red blood cell. Toxic molecule may help birds 'see' north and south Researchers at the University of Illinois report that a toxic molecule known to damage cells and cause disease may also play a pivotal role in bird migration. Mechanics: Ordinary meets quantum At the quantum level, the atoms that make up matter and the photons that make up light behave in a number of seemingly bizarre ways. Argonne, UC scientists reach milestone in study of emergent magnetism Scientists at the U.S. Department of Energy's Argonne National Laboratory and the University of Chicago have reached a milestone in the study of emergent magnetism. Researchers putting a freeze on oscillator vibrations University of Oregon physicists have successfully landed a one-two punch on a tiny glass sphere, refrigerating it in liquid helium and then dosing its perimeter with a laser beam, to bring its naturally occurring mechanical vibrations to a near standstill. Major Breakthrough in Early Detection and Prevention of AMD A team of researchers led by Dr. Jayakrishna Ambati at the University of Kentucky has discovered a biological marker for neovascular age-related macular degeneration (AMD), the leading cause of blindness in older adults. More Quantum Current Events and Quantum News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||