The number of transistors on a silicon chip has doubled every 18 months, but many observers believe that semiconductor technology will reach its limit in a decade or so. This has prompted the development of new devices, including so-called quantum cellular automata (QCA). So far, however, QCA based on semiconductors have only been operated at […]
The MIT team injected small quantities of air into a highly viscous liquid to stimulate the formation of air bubbles. As the bubbles reached the surface, da Silveira and colleagues punctured them with a needle. A high-speed camera recorded the collapse of the bubble. They discovered that the bubble bursts slowly through the hole punctured […]
One of the biggest challenges in quantum computation is to built “fault tolerant” logic gates. In the mid-1990s it was shown that this requires the time evolution of a quantum sub-system to be controlled by the state of a second sub-system. The evolution of the first system can manifest itself in several ways, including a […]
Mara Prentiss and colleagues at Harvard University in the US mounted two short wires on a sapphire substrate (Phys. Rev. Lett. 84 1124). When electric currents flow in opposite directions through the wires, a magnetic field is generated. An external magnetic field can then be used to cancel this field in the region between the […]
The team claim to have evidence for: an thin outer layer that is hot; a warm middle layer that is also optically thick; and a “cold” inner layer. The similarity of these layers to that of the corona, chromosphere and photosphere of the Sun suggest that similar physical processes may be at work in both […]
Previously is was thought that the result might have been due to some inadequacy in the data for the troposphere. However, Dian Gaffen from the US National Oceanic and Atmospheric Administration and colleagues have analyzed the data carefully and confirmed that although the temperature changes with height, the current average temperature measurements for the troposphere […]
Light emission from organic materials occurs through two separate processes: fluorescence – the process by which today’s organic semiconductors produce light – and phosphorescence. In fluorescence, a material absorbs charge carriers such as electrons and electron holes. The opposite charges meet up and combine to form an excited state known as an exciton. The material […]
The Delft group fabricated the electrodes by making a slit in a silicon nitride film with standard lithography. A series of platinum layers were then sputtered across the slit until the gap was reduced to 4 nanometers. The electrodes were then immersed in a droplet of dilute DNA solution. A voltage applied between the electrodes […]
The disagreement stems from a paper Gott published in Nature several years ago and recently discussed in the New Yorker magazine. In this paper Gott proposed a formula that suggests that by knowing how long an object, person, species or event has existed for, you can make a generalised prediction for how long it will […]
Molecules are poor candidates for the standard techniques used to create Bose-Einstein condensates because of their complicated internal vibrational and rotational structures. But by creating the molecules from atoms that are already inside a condensate, the Texas researchers have been able to put all the molecules into the same quantum state. The molecules, which have […]
