Condensed-Matter and Materials Physics The Science of the World Around Us (2007) / Chapter Skim
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7 How Will the Information Technology Revolution Be Extended?
7 How Will the Information Technology Revolution Be Extended?
Pages 127-143
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From page 127... ...
. Perhaps most exotically, quantum information science envisions computation and communication based not on the familiar laws of classical physics but instead on the often counterintuitive laws of quantum mechanics.
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From page 128... ...
For instance, the introduction to hard disk drives in 1998 of read-head sensors based on the giant magnetoresistance (GMR) effect greatly accelerated the above-mentioned doubling trend in information storage capacity.
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From page 129... ...
Now, sparked by new developments in condensed-matter and materials physics, magnetic sensors for hard disk drives are being reinvented again. Figure 7.1 shows a schematic of a GMR spin valve structure as originally utilized in the late 1990s and a schematic of the new magnetic tunnel junction (tunnel valve)
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From page 130... ...
(b) Schematic of magnetic alloy longitudinal recording layer showing amorphous grain boundaries as white and an average grain size of 8.5 nm.
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From page 131... ...
Figure 7.3 shows a high-resolution magnetic force microscopy image of magnetic bits tightly arranged along tracks in a magnetic recording medium. To extend the IT revolution, new devices for processing, storing, and communicating information will have to be invented.
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From page 132... ...
Novel computational strategies based on the self-organizing properties of biomolecules such as DNA have also been demonstrated, and approaches based on the manipulation of molecular configuration are being explored. Perhaps most exotically, quantum information science envisions computation and communica tion based not on the familiar laws of classical physics but instead on the some times counterintuitive laws of quantum mechanics.
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From page 133... ...
(a) An atomic force microscopy image of the device, which consists of a thin aluminum Hall cross that is oxidized and in contact with two ferromagnetic electrodes of different widths (FM1 and FM2)
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From page 134... ...
New Solid-State Memory Devices Solid-state memory devices are used for information storage when hard disk drives are too slow or bulky. Today there are several distinct varieties of solid-state
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From page 135... ...
Magnetic random access memory represents a digital "0" or "1" by the high or low electrical resistance of a magnetic tunnel junction. The basic concept of the magnetic tunnel junction goes back decades, but continuous and rapid advances in the physics of nanostructured magnetic materials are just beginning to make it practical as a memory device.
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From page 136... ...
While the commercialization of magnetic RAM and phase-change memory are most advanced, many other new memory devices are being explored in universi ties and industrial laboratories. A partial list of commercial development efforts includes memories based on changes in the conductivity of complex metal oxides, electrochemical reactions in small molecules, and electromechanical deformations of molecular-scale structures.
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From page 137... ...
Many basic questions need to be addressed. Can the spin-transfer effects being developed for magnetic memory devices also be employed in logic devices (see Figure 7.5)
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From page 138... ...
Multiferroics may thus help to realize useful spintronic devices that can be made very small. Magnetic fields are inherently nonlocal in nature, and hence as device density increases, stray magnetic fields can adversely affect neighboring bits.
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From page 139... ...
For example, densely packed arrays of organic-ligand-coated gold nanocrystals have been reported to belong to a new class of artificial solids with tunable electronic transport properties. Such properties stem from single-electron charging and quantum confinement energies at the level of individual particles, mediated by couplings to neighboring particles.
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From page 140... ...
Make any of these devices small enough and there will be only a few quantum particles in the system. In this limit, the laws of quantum mechanics manifest themselves most vividly, as has also been discussed in the National Research Council's atomic, molecular, and optical physics decadal survey. Thus, researchers need to traverse the threshold and look beyond the limits of classical physics.
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From page 141... ...
Quantum computing might disrupt the status quo by making present-day encryption methods obsolete because of its potential to rapidly break conventional codes. But simultaneously, it holds promise of providing quantum encryption schemes that are fundamentally unbreakable.
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From page 142... ...
The red arrow points to the heart of the qubit -- the Josephson junction device that might be used in a future quantum computer to represent a "1," a "0," or both values at once. SOURCE: Cour tesy of R
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From page 143... ...
Industrial laboratories must aggressively pursue new partnerships with the academic and national laboratory communities to promote critical, pre-competitive research that will lay the basis for future IT technologies (see Chapter 9 and the concluding recommendation)
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