Single Electron Reader Opens Path for Quantum Computing
ScienceDaily (Sep. 29, 2010) — A team led by engineers and physicists at the University of New South Wales (UNSW) in Sydney, Australia, have developed one of the key building blocks needed to make a quantum computer using silicon: a "single electron reader."
Artist's impression of a phosphorus atom (red sphere surrounded by a blue electron cloud, with spin) coupled to a silicon single-electron transistor, to achieve single-shot readout of the phosphorus electron spin. (Credit: William Algar-Chuklin, College of Fine Arts, The University of New South Wales)
Their work was published in the journal Nature.
Quantum computers promise exponential increases in processing speed over today's computers through their use of the "spin," or magnetic orientation, of individual electrons to represent data in their calculations.
In order to employ electron spin, the quantum computer needs both a way of changing the spin state (write) and of measuring that change (read) to form a qubit -- the equivalent of the bits in a conventional computer.
In creating the single electron reader, a team of engineers and physicists led by Dr Andrea Morello and Professor Andrew Dzurak, of the School of Electrical Engineering and Telecommunications at UNSW, has for the first time made possible the measurement of the spin of one electron in silicon in a single shot experiment. The team also includes researchers from the University of Melbourne and Aalto University in Finland.
"Our device detects the spin state of a single electron in a single phosphorus atom implanted in a block of silicon. The spin state of the electron controls the flow of electrons in a nearby circuit," said Dr Morello, the lead author of the paper, Single-shot readout of an electron spin in silicon.
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Read more here/Leia mais aqui: Science Daily
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Nature advance online publication 26 September 2010
doi:10.1038/nature09392; Received 28 April 2010; Accepted 2 August 2010; Published online 26 September 2010
Single-shot readout of an electron spin in silicon
Andrea Morello1, Jarryd J. Pla1, Floris A. Zwanenburg1, Kok W. Chan1, Kuan Y. Tan1, Hans Huebl1,5, Mikko Möttönen1,3,4, Christopher D. Nugroho1,5, Changyi Yang2, Jessica A. van Donkelaar2, Andrew D. C. Alves2, David N. Jamieson2, Christopher C. Escott1, Lloyd C. L. Hollenberg2, Robert G. Clark1,5 & Andrew S. Dzurak1
Australian Research Council Centre of Excellence for Quantum Computer Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales 2052, Australia
Australian Research Council Centre of Excellence for Quantum Computer Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
Department of Applied Physics/COMP, Aalto University, PO Box 15100, 00076 Aalto, Finland
Low Temperature Laboratory, Aalto University, PO Box 13500, 00076 Aalto, Finland
Present addresses: Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany (H.H.); Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA (C.D.N.); Department of Defence, Canberra, Australian Capital Territory 2600, Australia (R.G.C.).
Correspondence to: Andrea Morello1 Email: a.morello@unsw.edu.au
The size of silicon transistors used in microelectronic devices is shrinking to the level at which quantum effects become important1. Although this presents a significant challenge for the further scaling of microprocessors, it provides the potential for radical innovations in the form of spin-based quantum computers2, 3, 4 and spintronic devices5. An electron spin in silicon can represent a well-isolated quantum bit with long coherence times6 because of the weak spin–orbit coupling7 and the possibility of eliminating nuclear spins from the bulk crystal8. However, the control of single electrons in silicon has proved challenging, and so far the observation and manipulation of a single spin has been impossible. Here we report the demonstration of single-shot, time-resolved readout of an electron spin in silicon. This has been performed in a device consisting of implanted phosphorus donors9 coupled to a metal-oxide-semiconductor single-electron transistor10, 11—compatible with current microelectronic technology. We observed a spin lifetime of ~6 seconds at a magnetic field of 1.5 tesla, and achieved a spin readout fidelity better than 90 per cent. High-fidelity single-shot spin readout in silicon opens the way to the development of a new generation of quantum computing and spintronic devices, built using the most important material in the semiconductor industry.
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