Week of September 5, 2005

21st century scrolls

If you were wondering what a device with a flexible display might look like, you no longer have to wonder. Philips Electronics has built a concept portable electronic wireless reader that demonstrates one possibility. Readius is 3.9 inches by 2.4 inches by 0.8 inches and has narrow vertical display in compact mode and a 5-inch, 320-by-240-pixel display when the flexible display scrolls out.

The display uses Philips' previously developed electronic paper that uses polymer electronics and E Ink Corporation's electronic ink.

Phillips showed off the reader at the Internationale Funkausstellung (IFA) consumer electronics exhibition held in Berlin, Germany September 2 to 7, 2005. The company also demoed a 42-inch three-dimensional liquid crystal display, a digital television receiver for handheld devices, an image processing system that highlights the path of a soccer ball on a real-time television broadcast, and illuminated pillows and floor mats made with light emitting diodes embedded in cloth substrates.

Hierarchies promise better searches

Google's tremendous success arguably boils down to the company's PageRank algorithm, which calculates the relative importance of web pages and makes their Web search engine particularly effective. Researchers from Microsoft Research Asia, Hong Kong University of Science and Technology and Shanghai Jiao-Tong University in China have developed an alternative algorithm that performs better than PageRank in laboratory tests.

The researchers' Hierarchical Rank algorithm exploits the hierarchical structure of the Web. The algorithm first looks at relative importance at the domain and organizational level, for example stanford.edu and cs.stanford.edu, then at the relative importance of pages within those units. PageRank and other algorithms only look at page-to-page relationships. Hierarchical Rank allows pages to inherit some of the importance of the sites they occupy, which overcomes the difficulty new pages have in attaining visibility in search results, according to the researchers.

(Exploiting the Hierarchical Structure for Link Analysis, Special Interest Group Information Retrieval 2005 (SIGIR '05), August 15 to 19, 2005, Salvador, Brazil)

Store and forward qubits

Widespread use of quantum cryptography and other quantum communications techniques requires that qubits -- quantum particles like photons that are capable of storing information -- be sent over long distances, which in turn requires the ability to store qubits. Quantum cryptography uses the properties of photons to provide theoretically perfectly secure communications.

Qubits can be transmitted via photons and stored in atoms. Fading photons can transfer information to atoms at intermediate points along a network; those atoms can then generate new photons to carry the qubits over the next leg of their journey. The problem is that the wavelengths of light useful for transferring qubits to atoms is different from the wavelengths of light useful for transmitting qubits over optical fibers.

Researchers from the University of Geneva in Switzerland and the University of Nice-Sophia Antipolis in France have developed a technique for transferring qubits between photons of different wavelengths. The researchers demonstrated transferring qubits between photons with wavelengths of 1,310 nanometers, which is a common telecommunications wavelength, and photons with wavelengths of 710 nanometers, which is close to the wavelength absorbed and emitted by the alkaline atoms used for qubit storage.

(A Photonic Quantum Information Interface, Nature, September 1, 2005)

Sonic needles

Soundwaves have the power to move matter, and not just by generating unpleasant auditory sensations that clear people from a room. Researchers have been able to focus and shape soundwaves and use them to move small particles. Using this technique researchers have made virtual test tubes using sound.

Researchers from Nanyang Technological University in Singapore have taken the technique a step further by using ultrasound traps to hold particles in place and ultrasound virtual needles to spin the particles. The researchers can control the revolution speed, and were able to rotate seeds as fast as 300 revolutions per minute.

The technique could eventually be used to drive pumps and mixers in microfluidic devices including labs-on-a-chip.

(Controlled Rotation of Sound-Trapped Small Particles by an Acoustic Needle, Applied Physics Letters, August 29, 2005)