A giant orbital magnetic moment exists in graphene quantum dots, according to new work by physicists at the University of California Santa Cruz in the US. As well as being of fundamental interest for studying systems with relativistic electrons – that is those travelling at near-light speeds – the work could be important for quantum information science since these moments could encode information.
Graphene, a sheet of carbon just one atom thick, has a number of unique electronic properties, many of which arise from the fact that it is a semiconductor with a zero-energy gap between its valence and conduction bands. Near where the two bands meet, the relationship between the energy and momentum of charge carriers (electrons and holes) in the material is described by the Dirac equation and resembles that of a photon, which is massless.
These bands, called Dirac cones, enable the charge carriers to travel through graphene at extremely high, “ultra-relativistic” speeds approaching that of light. This extremely high mobility means that graphene-based electronic devices such as transistors could be faster than any that exist today.
In the future, communications networks and computers will use information stored in objects governed by the microscopic laws of quantum mechanics. This capability can potentially underpin communication with greatly enhanced security and computers with unprecedented power. A vital component of these technologies will be memory devices capable of storing quantum information to be retrieved at will.
Virginia Lorenz, a professor of physics at the University of Illinois Urbana-Champaign, studies Lambda-type optical quantum memory devices, a promising technology that relies on light interacting with a large group of atoms. She is developing a device based on hot metallic vapor with graduate student Kai Shinbrough.
As the researchers work towards a practical device, they are also providing some of the first theoretical analyses of Lambda-type devices. Most recently, they reported the first variance-based sensitivity analysis describing the effects of experimental noise and imperfections in Physical Review A.
Accelerating Leadership In Quantum Information Sciences — Dr. Charles Tahan, Ph.D., Assistant Director for Quantum Information Science (QIS); Director, National Quantum Coordination Office, Office of Science and Technology Policy, The White House.
Dr. Charles Tahan, Ph.D. is the Assistant Director for Quantum Information Science (QIS) and the Director of the National Quantum Coordination Office (NQCO) within the White House Office of Science and Technology Policy (https://www.quantum.gov/nqco/). The NQCO ensures coordination of the National Quantum Initiative (NQI) and QIS activities across the federal government, industry, and academia.
Dr. Tahan is on detail from the Laboratory for Physical Sciences (https://www.lps.umd.edu/) where he drove technical progress in the future of information technology as Technical Director. Research at LPS spans computing, communications, and sensing, from novel device physics to high-performance computer architectures. As a technical lead, Dr. Tahan stood up new research initiatives in silicon and superconducting quantum computing; quantum characterization, verification, and validation; and new and emerging qubit science and technology. As a practicing physicist, he is Chief of the intramural QIS research programs at LPS and works with students and postdocs from the University of Maryland-College Park to conduct original research in quantum information and device theory. His contributions have been recognized by the Researcher of the Year Award, the Presidential Early Career Award for Scientists and Engineers, election as a Fellow of the American Physical Society, and as an ODNI Science and Technology Fellow. He continues to serve as Chief Scientist of LPS.
Dr. Tahan earned a PhD in Physics at the University of Wisconsin-Madison in 2005 and a B.Sc. in Physics and Computer Science with Highest Honors from the College of William & Mary in 2000. From 2005–2007 he was a National Science Foundation Distinguished International Postdoctoral Research Fellow at the University of Cambridge, UK; the Center for Quantum Computing Technology, Australia; and the University of Tokyo, Japan. He served as chief technical consultant for quantum information science and technology programs in DARPA’s Microsystems Technology Office (MTO) while at Booz Allen Hamilton from 2007–2009. He has a long-term commitment to science and society including creating one of the first games meant to build intuition about quantum computing.
An older article but something the world is facing just like in certain sci-fi movies.
The reference publication of the movement in the 80s, the Earth First journal, featured a column called Ask Ned Ludd, in reference to the mythical character that gave name to the luddites. Jones thinks that neo-luddites are in fact misreading the original luddites, but he believes that understanding the difference between the old and modern ones tells us a lot about the ideology of the latter.
“Luddites were not anti-technology: they were skilled craftsmen, involved in a labour movement aimed at keeping their machines and their jobs,” he says. “That’s very different from the neo-luddites ideas of relinquishing civilisation and [of] nature as the supreme good.” Jones thinks neo-luddism is fed rather by “the idea of technology as a disembodied, transcendent, terrifying force outside the human”, which emerged in the mid 20th century, with the bomb and the rise of large-scale computing.
Because they are lightweight, have high energy density and are rechargeable, the batteries power many products, from laptops and cell phones to electric cars and toothbrushes.
However, current lithium-ion batteries have reached the limit of how much energy they can store. That has researchers looking for more powerful and cheaper alternatives.
Two-dimensional (2D) magnetic insulators, which are electrically insulating materials with long-range magnetic order, could be used to fabricate compact magneto-electric or magneto-optical devices. Efficiently and reliably controlling the properties of these atomically thin magnets through electrical means, however, has so far proved to be highly challenging, as the materials’ charge levels often cannot be largely adjusted and their crystal fields cannot be considerably altered using external electric fields.
Researchers at University of Maryland and their collaborators recently devised a new strategy that could be used to efficiently control 2D magnetic insulators. This strategy, outlined in a paper in Nature Electronics, relies on the use of a thin ferroelectric polymer that can modulate the 2D materials’ magnetic responses.
“When it comes to electronic devices, people are primarily pursuing a smaller form factor (relating to higher integration density, which means more devices can be integrated on the unit area/volume of a chip), lower energy consumption, and higher performance,” Cheng Gong, the lead principal investigator for the study, told Tech Xplore.
