Monday, June 10, 2013

Quantum Teleportation

Quantum teleportation involves the exchange of information in the form of quantum states, not matter, between two points with the use of quantum entanglement. In principle, the distances can be arbitrarily long and works even if the location of the recipient is not known.  Cryptography is a key element in quantum communications and quantum computers. It takes advantage of quantum entanglement, the phenomenon in which two objects, such as photons, are connected in such a way, even at great distances, that changing the state of one instantly changes the state of the other. If an eavesdropper intercepts the message, this entangled state is disrupted and the aggression is thus noticed.

The latest article in a recent series of breakthroughs in quantum teleportation involves researchers at the Niels Bohr Institute who have reported in Nature Physics (1) that they have succeeded in teleporting information between two clouds of gas atoms, and they have done so every single time they attempted. The experiment involves two glass containers, each containing caesium gas atoms. Information is teleported from one glass container to the other by means of a laser beam of light which becomes entangled with the gas atoms. Even though the glass containers were only a half meter apart, it “is entirely due to the size of the laboratory,” explains Eugene Polzik. “We could increase the range if we had the space and, in principle, we could teleport information, for example, to a satellite.” (2)

Anton Zeilinger’s group in Vienna have succeeded in teleporting information over long distances. In a paper in Nature in 2012 (3), an international team led by Zeilinger reported successfully transmitting quantum states over a distance of 143 kilometers, between two Canary Islands.

Saturday, June 1, 2013

Evolution In Action

In a paper in the May 30 issue of Current Biology, (1,2) researchers have been able to solve a problem that has perplexed biologists for over two centuries: the evolution of the turtle shell. They have been able to fill what they deem a 35 to 50 million year gap by the study of an extinct South African reptile known as Eunotosaurus africanus. In doing so, they have given us a very good example of evolution in action.

According to the author, Tyler Larson, the turtle shell is a structure whose evolution started over 260 million years ago in the Permian period. The shell is actually composed of approximately 50 bones, the fusion of ribs and vertebrae, the only animals that have evolved their shell in this way. Other animals with shells use bony scales as a protective shell and retain their ribs in order to allow for the mechanics of breathing. The turtles have apparently solved this problem by the evolution of a muscular sling.

Eunotosaurus displays several characteristics—such as a reduced number of elongated trunk vertebrae and reorganization of respiratory muscles to the ventral side of the ribs, among others—which conform to predictions that the initial transformations occurred by the Middle Permian period. The known turtle fossils discovered until recently dated back about 215 million years and had fully developed shells. In 2008 the discovery of Odontochelys semitestacea, a reptile about 220 million years old, showed that it had a fully developed plastron, the belly side of the shell, but only a partial carapace. Eunotosaurus is 40 million years older and it has the broadened ribs and lack of intercostal muscles running between its ribs that are found only in turtles, but lacks broad spines on their vertebrae and other features common to turtles and Odontochelys.