July 6, 2006

	In This Issue:
	New Ion Trap May Lead to Large Quantum Computers
	NIST RoboCrane® Cuts Aircraft Maintenance Costs
	Stress Management: X-Rays Reveal Si Thin-Film Defects
	Magnetic Ties May Explain High-Temp Superconductors
	Rust Never Sleeps: New SRM Aids Coated Steel Industry
	Quick Links
	NIST, UM Program To Support Nanotech Development

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New Ion Trap May Lead to Large Quantum Computers

False-color images of 1, 2, 3, 6, and 12 magnesium ions loaded into NIST's new planar ion trap. Red indicates areas of highest fluorescence, or the centers of the ions. As more ions are loaded in the trap, they squeeze closer together, until the 12-ion string falls into a zig-zag formation. Credit: Signe Seidelin and John Chiaverini/NIST Click here for hi-res version.

Physicists at the National Institute of Standards and Technology (NIST) have designed and built a novel electromagnetic trap for ions that could be easily mass produced to potentially make quantum computers large enough for practical use. The new trap, described in the June 30 issue of Physical Review Letters,* may help scientists surmount what is currently the most significant barrier to building a working quantum computer—scaling up components and processes that have been successfully demonstrated individually.

Quantum computers would exploit the unusual behavior of the smallest particles of matter and light. Their theoretical ability to perform vast numbers of operations simultaneously has the potential to solve certain problems, such as breaking data encryption codes or searching large databases, far faster than conventional computers. Ions (electrically charged atoms) are promising candidates for use as quantum bits (qubits) in quantum computers. The NIST team, one of 18 research groups worldwide experimenting with ion qubits, previously has demonstrated at a rudimentary level all the basic building blocks for a quantum computer, including key processes such as error correction, and also has proposed a large-scale architecture.

NIST's novel planar ion trap was designed to be easily mass produced, potentially enabling quantum computers large enough for practical use. The trap uses gold electrodes to confine magnesium ions 40 micrometers above the plane of the electrodes. Laser beams are used to create ions from the metal vapor and then cool them. Credit: Signe Seidelin and John Chiaverini/ NIST Click here for hi-res version.

The new NIST trap is the first functional ion trap in which all electrodes are arranged in one horizontal layer, a “chip-like” geometry that is much easier to manufacture than previous ion traps with two or three layers of electrodes. The new trap, which has gold electrodes that confine ions about 40 micrometers above the electrodes, was constructed using standard microfabrication techniques.

NIST scientists report that their single-layer device can trap a dozen magnesium ions without generating too much heat from electrode voltage fluctuations—also an important factor, because heating has limited the prospects for previous small traps. Microscale traps are desirable because the smaller the trap, the faster the future computer. Work is continuing at NIST and at collaborating industrial and federal labs to build single-layer traps with more complex structures in which perhaps 10 to 15 ions eventually could be manipulated with lasers to carry out logic operations.

The work was supported in part by the National Security Agency/Disruptive Technology Office (formerly Advanced Research and Development Activity).

Background on NIST quantum computing research: www.nist.gov/public_affairs/quantum/quantum_info_index.html.

*S. Seidelin, J. Chiaverini, R. Reichle, J.J. Bollinger, D. Leibfried, J. Britton, J.H. Wesenberg, R.B. Blakestad, R.J. Epstein, D.B. Hume, W.M. Itano, J.D. Jost, C. Langer, R. Ozeri, N. Shiga, and D.J. Wineland. 2006. A microfabricated surface-electrode ion trap for scalable quantum information processing. Physical Review Letters. June 30.

Media Contact:
Laura Ost, laura.ost@nist.gov, (301) 975-4034

 

NIST RoboCrane® Cuts Aircraft Maintenance Costs

Click here for hi-res version.

A worker in a protective cab on a NIST-developed revolutionary robotic platform strips paint off a U.S. Air Force C-130. The easily maneuverable platform, that uses computer-controlled cables to "float" around the aircraft, promises to drastically reduce paint-stripping time per airplane, cut maintenance costs and lessen incidents of operator stress and injury. Credit: Photos by N.E. Wasson Jr., U.S. Technology Corp.

Click here for hi-res version. Credit: Photos by N.E. Wasson Jr., U.S. Technology Corp.

A revolutionary robotic platform developed by the National Institute of Standards and Technology (NIST) has been adapted for the U.S. Air Force to address the critical, expensive, and nasty work of stripping old paint from large aircraft. The robot’s work platform, which “floats” in mid air suspended by a web of computer-controlled cables, promises to drastically reduce paint-stripping time per airplane, cut costs and lessen incidents of operator stress and injury. 

Air Force maintenance rules require that the coatings on large aircraft be stripped off and replaced every five to six years. The stripping process is difficult and hazardous, filling the air with toxic dust and vapors. The task is currently done by maintenance workers in hot, movement–inhibiting protective suits climbing on scaffolding erected around the airplane. Using the new “Aerial Multi-axis Platform” (AMP), a worker in a protected cab can operate the automated high-pressure blast nozzles of the paint-stripping machinery, moving easily around the aircraft suspended from the aircraft hanger’s ceiling. This robotic approach allows the operator to guide several concurrent nozzles, vastly improving productivity over the conventional single nozzle, hands-on approach. The AMP uses NIST’s RoboCrane® technology in which six hoist cables from three upper support points tautly support, stabilize, and maneuver the work platform. It eliminates the need for scaffolding and other ground-base equipment that is time consuming to set up and hinders other operations within the hanger.

The AMP was adapted for aircraft maintenance operations by NIST in partnership with the U.S. Technology Corporation, with sponsorship from the Air Force Research Laboratory (AFRL). According to AFRL’s Manufacturing Technology program, the AMP dramatically improves the quality and productivity of the paint stripping operations—one third of the overall maintenance process. Tests demonstrate that a worker with the AMP can strip up to 10-20 square feet per minute. A single operator can comfortably work an entire eight hour shift rather than taking the frequent breaks needed with the current de-painting process. The AMP design reduces the process time to strip old paint from an aircraft by 40-50 percent, the equivalent of four to five days for a C-5 aircraft.

Two production AMP systems are being installed at the Air Force’s Warner Robins Air Logistics Center in Georgia for C-130 coating removal. The technology also is expected to be of use to the commercial aircraft industry.

*See http://www.isd.mel.nist.gov/projects/robocrane.

Media Contact:
John Blair, john.blair@nist.gov, (301) 975-4261

 

Stress Management: X-Rays Reveal Si Thin-Film Defects

X-ray topographs of three different strata of a strained-silicon wafer show close correspondence in defects from the base silicon layer (top) through the final strained-silicon layer (bottom). Color has been added for contrast, one particular defect area is highlighted. Credit: NIST Click here for hi-res version.

Pile-ups, bad on the freeway, also are a hazard for the makers of high-performance strained-silicon (Si) semiconductor devices. A sensitive X-ray diffraction imaging technique developed by researchers at the National Institute of Standards and Technology (NIST) can help manufacturers avoid the latter—a bunching up of crystal defects caused by the manufacturing process for strained-silicon films.

Strained silicon is a new, rapidly developing material for building enhanced-performance silicon-based transistors. Introducing a slight tensile strain in the lattice of the silicon crystal dramatically improves the mobility of charges in the crystal, enabling faster, higher-performance devices. The strain is achieved by first growing a relatively thick crystalline layer of silicon-germanium (SiGe) on the normal silicon substrate wafer, and then growing a thin film of pure silicon on top. The difference in lattice spacing between pure silicon and SiGe creates the desired strain, but also creates occasional defects in the crystal that degrade performance. The problem is particularly bad when the defects cluster together in so-called “pile-ups.”

One of the best methods for studying crystal defects is to observe the image of X-rays diffracted from the crystal planes, a technique called X-ray topography. Until now, however, it’s been impossible to study the interaction of defects in the multiple layers of these complex Si – SiGe – Si wafers. In a recent paper in Applied Physics Letters,* researchers from NIST and AmberWave Systems Corporation (Salem, N.H.) detail a high-resolution form of X-ray topography that can distinguish individual crystal defects layer by layer. The technique combines an extremely low-angle incident X-ray beam (“glancing incidence”)  to increase the signal from one layer over another and the use of highly monochromatic X-rays tuned to separate the contributions from each layer based on their different lattice spacings.

Their results show that crystal defects initially created at the interface between the silicon wafer and the SiGe layer become “templates” that propagate through that layer and create matching defects in the strained-silicon top layer. These defects, in turn, are notably persistent, remaining in the strained-silicon even through later processing that includes stripping the layer off, bonding it to an oxidized silicon wafer, and annealing it to create strained-silicon-on-insulator (SSOI) substrates.

The research was performed at Argonne National Laboratory’s Advanced Photon Source, and supported in part by the Department of Energy.

*D.R. Black,  J.C. Woicik, M. Erdtmann and T.A. Langdo. Imaging defects in strained-silicon thin films by glancing-incidence x-ray topography. Applied Physics Letters 88, 224102. Published online June 2, 2006.

Media Contact:
Michael Baum, michael.baum@nist.gov, (301) 975-2763

 

Magnetic Ties May Explain High-Temp Superconductors

When it comes to superconductivity, magnetic excitations may top good vibrations. Scientists working at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) in collaboration with physicists from the University of Tennessee (UT) and Oak Ridge National Laboratory (ORNL) have discovered strong evidence that magnetic fluctuations are key to a universal mechanism for pairing electrons and enabling resistance-free passage of electric current in high-temperature superconductors. Their work is described in the July 6 issue of Nature.*

Phonons—vibrations in the atomic latticework—are responsible for the pairing-up of electrons in conventional, low-temperature, superconductors that allows for the characteristic, resistance-free flow of electrons. High-temperature superconductors, which have been objects of intense interest since their discovery in 1986, need some other pairing mechanism—phonons have been ruled out.

There are two main classes of high-temperature superconductors, those which have a surplus of electrons and those that have a surplus of electron vacancies or “holes.” Previous work by other researchers has shown that magnetism plays a role in the superconductivity of the latter materials, but the mechanism for the former remained elusive. This work, using neutron probes at NCNR and ORNL's High Flux Isotope Reactor, forges a key link by demonstrating a magnetic resonance in an electron-doped, high-temperature superconductor.

The finding should boost efforts to develop a variety of useful technologies now considered impractical for conventional superconductors. Examples include loss-free systems for storing and distributing electric energy, superconducting digital routers for high-speed communications, and more efficient generators and motors.

NIST, the National Science Foundation and the Department of Energy supported the research.

For more information, see www.nist.gov/public_affairs/releases/magnetism_key.html.

*S.D. Wilson, P. Dai, S. Li, S. Chi, H.J. Kang, J.W. Lynn. 2006. Resonance in the electron-doped high-transition-temperature superconductor Pr0.88LaCe0.12CuO4-δ Nature. July 6, 2006.

Media Contact:
Mark Bello, mark.bello@nist.gov, (301) 975-3776

 

Rust Never Sleeps: New SRM Aids Coated Steel Industry

The National Institute of Standards and Technology (NIST) has developed a new reference material to aid quality control in the steel coatings industry. The new Standard Reference Material (SRM) 2426 is a 55% aluminum-zinc alloy certified by NIST not only for the aluminum and zinc content but also for silicon and iron, two important contaminants.

First introduced commercially in the 1970s, 55% Al-Zn is widely used as a tough, corrosion-resistant coating for sheet steel, particular in roofing. The Zinc Aluminum Coaters Association (ZAC) claims the latter as the fastest-growing coated steel product in the world. The alloy is applied to sheet steel using a hot-dip coating process. Huge coils of cold-rolled steel wind through a vat of the molten alloy at speeds up to three meters a second. The coating must meet industrial standards for thickness and chemical composition, so the steel typically is sampled for quality control at regular intervals.

Over time, the molten alloy vat gradually accumulates iron and silicon from the steel, and must be monitored to prevent the concentration of contaminants from getting too high. The new NIST reference material represents 55% aluminum-zinc alloy that is near the maximum allowable concentrations of iron and silicon as set by ASTM*, and can be used by steel laboratories to validate the performance of their test methods at the critical upper specification limits.

NIST SRM 2426 - 55% Aluminum-Zinc Alloy was developed in cooperation with ASTM International Committee E01 on Analytical Chemistry of Metals, Ores and Related Materials. It is intended primarily for use in evaluating chemical and instrumental methods of analysis. Certified values are provided for the four elements aluminum (Al), zinc (Zn), silicon (Si), and iron (Fe).
 
The material from which SRM 2426 was developed is better known by one of several trade names including Galvalume® in North America and, in South America, Zincalume®, Zintro Alum™ and Galval™. From 1972 to 2004, nearly 20 million tons of steel coated with this alloy were produced in North America.

More information on SRM 2426 is available from NIST’s Standard Reference Materials office, www.nist.gov/srm.

*ASTM A924/A924M-04 Standard Specification For General Requirements For Steel Sheet, Metallic-Coated By The Hot-Dip Process.

Media Contact:
Michael Baum, michael.baum@nist.gov, (301) 975-2763

 

Quick Links

NIST, UM Program To Support Nanotech Development

The National Institute of Standards and Technology (NIST) and the University of Maryland (UM) have joined in a $1.5 million cooperative program that will further NIST’s efforts to develop measurement technology and other new tools designed to support all phases of nanotechnology development, from discovery to manufacture. The competitively awarded grant, renewable for up to five years, also will accelerate the scale-up of NIST’s new Center for Nanoscale Science and Technology (CNST), launched in March 2006. UM research associates will work on jointly defined projects aligned with the center’s mission to develop the knowledge and technical infrastructure that underpins nanotechnology development. They also will collaborate with visiting researchers who come to the CNST to use measurement instruments and other advanced equipment in its Nanofabrication Facility, a national resource available to collaborators and outside users. For more information, see www.nist.gov/public_affairs/releases/nistgrant_toumd.html.

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Editor: Michael Baum

Date created: 7/5/06
Date updated: 7/6/06
Contact: inquiries@nist.gov