With the ever-decreasing scale of electronics, quantum physicists say it is crucial to find new approaches for making this happen. "As consumers want more powerful technology, we need to find new ways to supply this demand" says the University of Sydney's Dane McCamey.
One leading approach is "spintronics", where the magnetic character, or spin, of electrons and even nuclei are used to store information. Scientists have now shown that the spin of atomic nuclei in silicon can store information for over a minute and that the information can then be read out electrically, an important step in linking spintronics with classical electronics.
The research is published in the journal Science by an international team comprising Dane McCamey, Hans van Tol, Gavin Morley and Christoph Boehme.
The experiments are the first to controllably flip the state of nuclear spins in silicon between a "0" and a "1" and then read out the effect this has on an electric current. Unique equipment for controlling electronic and nuclear spins in high magnetic fields and at very low temperatures made this possible at the National High Magnetic Field Laboratory (NHMFL) in Tallahassee, Florida.
"Our use of silicon makes these findings particularly exciting for semiconductor companies, who are experts in silicon" the lead author, Dane McCamey (Universities of Sydney and Utah) commented. "Because the nuclear spins are better isolated from their environment than electronic spins, they can store information for longer" added Christoph Boehme, from the University of Utah.
"The high magnetic fields we use enable the electron spins to be lined up, initializing them so they are ready to store information" pointed out Hans van Tol, of the NHMFL "We also show that we can line up the nuclear spins too".
"Electrical detection of electron spins is also the leading approach for detecting quantum information in silicon" said Gavin Morley (University College London and London Centre for Nanotechnology). "Future experiments could use this method to study quantum information stored in nuclear spins".
"Electronic Spin Storage in an Electrically Readable Nuclear Spin Memory with a Lifetime >100 Seconds" by Dane R. McCamey, Hans van Tol, Gavin W. Morley and Christoph Boehme, Science 330, 1652 (2010). The article is available online here. Scientific American covered these findings here.
This work was supported by the Australian Research Council, the UK Royal Commission for the Exhibition of 1851, the UK EPSRC COMPASSS grant, the US National Science Foundation and the National High Magnetic Field Laboratory (NHMFL). The NHMFL is funded by the State of Florida, the US Department of Energy, and the US National Science Foundation.
Electrons (green arrows) flow through a silicon chip and some are trapped by phosphorus atoms (blue arrows). A phosphorus atom can only capture a second electron if the two electrons have opposite spin, and this leads to a decrease in the electric current. This spin-trap was used to electrically read out the nuclear spin (red arrow), where information was stored for over 100 seconds. Animated image by Gavin W Morley.
University of Utah:
The University of Utah is the State of Utah's oldest and largest institution of higher education and is a major research university. The University offers over 100 undergraduate and more than 90 graduate degree programs to over 29,000 students. It is ranked as one of the top public research universities of the United States. Website: http://www.utah.edu
National High Magnetic Field Laboratory (NHMFL)
The National High Magnetic Field Laboratory develops and operates state-of-the-art, high-magnetic-field facilities that faculty and visiting scientists and engineers use for research. The laboratory is sponsored by the National Science Foundation and the state of Florida. To learn more visit http://www.magnet.fsu.edu
London Centre for Nanotechnology:
The London Centre for Nanotechnology is an interdisciplinary joint enterprise between University College London and Imperial College London. In bringing together world-class infrastructure and leading nanotechnology research activities, the Centre has the critical mass to compete with the best facilities world-wide. Research programmes are aligned to three key areas, namely Planet Care, Healthcare and Information Technology and exploit core competencies in the biomedical, physical and engineering sciences. Website: http://www.london-nano.com
UCL (University College London)
Founded in 1826, UCL was the first English university established after Oxford and Cambridge, the first to admit students regardless of race, class, religion or gender, and the first to provide systematic teaching of law, architecture and medicine. UCL is the fourth-ranked university in the 2009 THES-QS World University Rankings. UCL alumni include Marie Stopes, Jonathan Dimbleby, Lord Woolf, Alexander Graham Bell, and members of the band Coldplay. UCL currently has over 12,000 undergraduate and 8,000 postgraduate students. Its annual income is over £600 million. http://www.ucl.ac.uk
The University of Sydney
The University of Sydney is Australia's founding higher education establishment. It is a member of the Group of Eight research intensive universities and enrols over 4,000 postgraduate research students. The University's commitment to excellence in research underpins an approach to research-led teaching that has been acclaimed for its excellence. Graduates of the university can be found at the top of many fields throughout the world. Among those who have gained international recognition are four Prime Ministers of Australia (Barton, McMahon, Whitlam and Howard); Nobel Laureates Sir John Cornforth (chemistry), Sir Robert Robinson (chemistry) and Emeritus Professor John Harsanyi (economics); filmmakers Phil Noyce, Jane Campion and Bruce Beresford; designer Marc Newson; soprano Yvonne Kenny; conductor Simone Young; writers Germaine Greer and Clive James; and President of the Royal Society Lord May. For more information visit http://www.sydney.edu.au.