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Disorderly conduct: Probing the role of disorder in quantum coherence

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TechAndComputer (July 19, 2012) — A new experiment conducted at the Joint Quantum Institute (JQI)* examines the relationship between quantum coherence, an important aspect of certain materials kept at low temperature, and the imperfections in those materials. These findings should be useful in forging a better understanding of disorder, and in turn in developing better quantum-based devices, such as superconducting magnets.

Most things in nature are imperfect at some level. Fortunately, imperfections -- a departure, say, from an orderly array of atoms in a crystalline solid -- are often advantageous. For example, copper wire, which carries so much of the world's electricity, conducts much better if at least some impurity...

Diamond used to produce graphene quantum dots and nano-ribbons of controlled structure

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TechAndComputer (May 17, 2012) — Kansas State University researchers have come closer to solving an old challenge of producing graphene quantum dots of controlled shape and size at large densities, which could revolutionize electronics and optoelectronics.

Vikas Berry, William H. Honstead professor of chemical engineering, has developed a novel process that uses a diamond knife to cleave graphite into graphite nanoblocks, which are precursors for graphene quantum dots. These...

Quantum physicists show a small amount of randomness can be amplified without limit

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TechAndComputer (May 16, 2012) — Once again quantum physics gives us philosophical implications: physicists showed how a small amount of randomness can be amplified without limit.

Classical physics is deterministic: for example, we can determine the position and velocity of a particle at any time in the future. Quantum theory, on the other hand, states that there exist processes which are fundamentally random: for instance, the outcomes of measurements of quantum particles seem...

Quantum dots brighten the future of lighting

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TechAndComputer (May 8, 2012) — With the age of the incandescent light bulb fading rapidly, the holy grail of the lighting industry is to develop a highly efficient form of solid-state lighting that produces high quality white light.

One of the few alternative technologies that produce pure white light is white-light quantum dots. These are ultra-small fluorescent beads of cadmium selenide that can convert the blue light produced by an LED into a warm white light with a spectrum...

First light: Researchers develop new way to generate superluminal pulses

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TechAndComputer (May 3, 2012) — Researchers at the National Institute of Standards and Technology (NIST) have developed a novel way of producing light pulses that are "superluminal" -- in some sense they travel faster than the speed of light. The technique, called four-wave mixing, reshapes parts of light pulses and advances them ahead of where they would have been had they been left to travel unaltered through a vacuum. The new method could be used to improve the timing of...