New technologies that exploit quantum behavior for computing and other applications are closer than ever to being realized due to recent advances, says the University of Chicago’s David Awschalom and his co-authors in an article published in the March 8 issue of the journal Science.
“It is truly remarkable to witness the rate of scientific discoveries and proposed applications occurring around the world,” said Awschalom, the Liew Family Professor of Molecular Engineering at the University of Chicago. “From advanced computation to secure data transmission to subatomic imaging technologies, advances in the field of quantum spintronics are taking us in unexpected and exciting directions,” he added.
These advances could enable the creation of immensely powerful computers as well as other applications, such as highly sensitive detectors capable of probing biological systems. “We are really excited about the possibilities of new semiconductor materials and new experimental systems that have become available in the last decade,” said Jason Petta, one of the authors of the report and an associate professor of physics at Princeton University.
Awschalom’s co-authors also included Lee Basset of the University of California, Santa Barbara, Andrew Dzurak of the University of New South Wales, and Evelyn Hu of Harvard University. Two significant breakthroughs enable this progress, according to Awschalom and his co-authors.
The first is the ability to control quantum units of information, known as quantum bits, at room temperature. Until recently, temperatures near absolute zero were required, but new diamond-based materials allow spin qubits to be operated on a tabletop, at room temperature. Diamond-based sensors could also be used to image single molecules, as demonstrated by Awschalom and researchers at Stanford University and IBM Research (Science, 2013).
The second big development is the ability to control these quantum bits, or qubits, for several seconds before they lapse into classical behavior, a feat achieved by Dzurak's team (Nature, 2010) and Princeton researchers led by Stephen Lyon, a professor of electrical engineering (Nature Materials, 2012). The development of highly pure forms of silicon, the same material used in today's classical computers, has enabled researchers to control a quantum mechanical property known as "spin." At Princeton, Lyon and his team demonstrated the control of spin in billions of electrons, a state known as coherence, for several seconds by using a pure form of silicon called silicon-28.
Quantum-based technologies exploit the physical rules that govern very small particles—such as atoms and electrons—rather than the classical physics evident in everyday life. New technologies based on "spintronics" rather than electron charge, as is currently used, would be much more powerful than current technologies.
In quantum-based systems, the direction of the spin (either up or down) serves as the basic unit of information, which is analogous to the 0 or 1 bit in a classical computing system. Unlike our classical world, an electron spin can assume both a 0 and 1 at the same time, a feat called entanglement, which greatly enhances the ability to do computations.
A remaining challenge is to develop robust quantum architectures that include a means to transmit information over long distances. This includes developing ways to scale up the number of qubits from a handful to hundreds or thousands, according to the researchers. Single quantum bits have been made using a variety of materials, including electronic and nuclear spins, as well as superconductors.
The Spintech VII International School and Conference will explore some of these and related topics when it convenes from July 29 to Aug. 2 in Chicago. Spintech VII is sponsored by UChicago’s Institute for Molecular Engineering, the California Nanosystems Institute at the University of California, Santa Barbara, and Argonne National Laboratory. For more information, see spintech7.cnsi.ucsb.edu.
Adapted from an article provided by Princeton University: blogs.princeton.edu/research/2013/03/07/quantum-computing-moves-forward-science