For the first time, physicists have convincingly demonstrated that physically separated particles in solid-state devices can be quantum-mechanically entangled. The achievement is analogous to the quantum entanglement of light, except that it involves particles in circuitry instead of photons in optical systems. Both optical and solid-state entanglement offer potential routes to quantum computing and secure communications, but solid-state versions may ultimately be easier to incorporate into electronic devices. The experiment is reported in an upcoming issue of Physical Review Letters and highlighted with a Viewpoint in the January 11 issue of Physics (http://physics.aps.org.)

This is an SEM image of a typical Cooper pair splitter.  The bar is 1 micrometer. A central superconducting electrode (blue) is connected to two quantum dots engineered in the same single wall carbon nanotube (in purple). Entangled electrons inside the superconductor can be coaxed to move in opposite directions in the nanotube, ending up at separate quantum dots, while remaining entangled. Credit: L.G. Herrmann, F. Portier, P. Roche, A. Levy Yeyati, T. Kontos, and C. Strunk

In optical entanglement experiments, a pair of entangled photons may be separated via a beam splitter. Despite their physical separation, the entangled photons continue to act as a single quantum object. A team of physicists from France, Germany and Spain has now performed a solid-state entanglement experiment that uses electrons in a superconductor in place of photons in an optical system.

As conventional superconducting materials are cooled, the electrons they conduct entangle to form what are known as Cooper pairs. In the new experiment, Cooper pairs flow through a superconducting bridge until they reach a carbon nanotube that acts as the electronic equivalent of a beam splitter. Occasionally, the electrons part ways and are directed to separate quantum dots -- but remain entangled. Although the quantum dots are only a micron or so apart, the distance is large enough to demonstrate entanglement comparable to that seen in optical systems.

(2) Comments posted about this in the forum

Cells that protect nerves are the likely origin of the Devil Facial Tumour Disease (DFTD) that has been devastating Australia's Tasmanian devil population, an international team of scientists has discovered.

Devil Facial Tumour Disease (DFTD) is a transmissible cancer that affects only Tasmanian devils and was first reported in 1996. It is spread by biting and quickly kills the animals. The disease is characterised by large tumours, mostly on the face and mouth, which often spread to internal organs.

The research collaboration, led by Australian scientists, has found that DFTD originates from cells called Schwann cells, which protect peripheral nerve fibres.

The results have been published today in the international journal Science.

Dr. Tony Papenfuss from the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia, has identified Schwann cells as the likely origin of the devil facial tumor disease that has been devastating Australia's Tasmanian devil population. Credit: Cameron Wells, Walter and Eliza Hall Institute

Through the discovery, the team has now identified a genetic marker that could be used to accurately diagnose the perplexing cancer, which has seen the devil listed as endangered and facing extinction.

Lead author Dr Elizabeth Murchison from the Australian National University said the Schwann cell discovery was significant as there are currently no specific diagnostic tests, treatments or vaccines available for the disease.

"We took biopsies from devil tumours and extracted genetic data from them," Dr Murchison said.

Dr Tony Papenfuss from Melbourne's Walter and Eliza Hall Institute then led the team that determined which genes were switched on in the tumours and identified their genetic signature.

"When we compared the signature of the tumours to other normal tissues we found the tumours were most like Schwann cells," Dr Papenfuss said.

Associate Professor Greg Woods from the University of Tasmania's Menzies Research Institute said the Schwann cell find was an important step in the process to further understand the disease.

"Devils develop tumours of all different types and the genetic markers we have identified are useful for telling apart the tumours that occur in DFTD from other kinds of tumours," Associate Professor Woods said.

The Schwann cell research was conducted as part of the Save the Tasmanian Devil Program's efforts to further explore DFTD. It was supported by the National Health and Medical Research Council and the University of Tasmania's Dr Eric Guiler Tasmanian Devil Research Grant.

(1) Comments posted about this in the forum

Using the NASA/ESA Hubble Space Telescope, astronomers have uncovered two distinct kinds of "rejuvenated" stars in the globular cluster Messier 30. A new study shows that both stellar collisions and a process sometimes called vampirism are behind this cosmic "face lift". The scientists also uncover evidence that both sorts of blue stragglers were produced during a critical dynamical event (known as "core collapse") that occurred in Messier 30 a few billion years ago.

This illustration demonstrates the two ways that blue stragglers — or "rejuvenated" stars — in globular clusters form. The upper illustration shows the collision model where two low-mass stars in an overcrowded environment experience a head-on collision, combining their fuel and mass and to form a single hot star. The lower illustration depicts the "vampire" model consisting of a pair of stars that undergo a transformation, with the lower-mass star draining its larger-mass companion of hydrogen that fuels its rebirth. Credit: NASA/ ESA

Stars in globular clusters are generally extremely old, with ages of 12-13 billion years. However, a small fraction of them appear to be significantly younger than the average population and, because they seem to have been left behind by the stars that followed the normal path of stellar evolution and became red giants, have been dubbed blue stragglers. Blue stragglers appear to regress from "old age" back to a hotter and brighter "youth", gaining a new lease on life in the process. A team of astronomers used Hubble to study the blue straggler star content in Messier 30, which formed 13 billion years ago and was discovered in 1764 by Charles Messier. Located about 28 000 light-years away from Earth, this globular cluster — a swarm of several hundred thousand stars — is about 90 light-years across.

Although blue stragglers have been known since the early 1950s, their formation process is still an unsolved puzzle in astrophysics. "It’s like seeing a few kids in the group picture of a rest-home for retired people. It is natural to wonder why they are there," says Francesco Ferraro from the University of Bologna in Italy, lead author of the study that will be published this week in Nature. Researchers have been studying these stars for many years and knew that blue stragglers are indeed old. They were thought to have arisen in a tight binary system. In such a pair, the less massive star acts as a "vampire", siphoning fresh hydrogen from its more massive companion star. The new fuel supply allows the smaller star to heat up, growing bluer and hotter — behaving like a star at an earlier stage in its evolution.

(1) Comments posted about this in the forum