Integrated quantum circuit is most complex ever.

Experimental set-up

Researchers in the UK, Japan and the Netherlands have fabricated the most functionally complex integrated quantum circuit ever from a single material, capable of generating photons and entangling them at the same time. The circuit consists of two photon sources on a silicon chip that interfere quantum mechanically. Its inventors say that it could be used in quantum information processing applications and in complex on-chip quantum optics experiments.

Quantum interference is at the heart of many quantum information processing algorithms and technologies. However, to observe this uniquely quantum-mechanical effect, the photons employed need to be indistinguishable – that is, they need to be identical in every possible way. They also need to be produced from identical photon sources, something that has proved difficult to do in the past.

A team of researchers led by Mark Thompson of the University of Bristol in the UK has now succeeded in overcoming this hurdle and has managed to realize two identical photon sources on a single silicon chip for the first time. “These sources produce entangled light – which we can control – and quantum mechanically interfere on the same chip,” explains Thompson.

Four-wave mixing

To generate the photons on their chip, the researchers began by injecting a strong infrared pump laser beam into it. The beam produces photon pairs via a nonlinear interaction with the silicon material in a process called spontaneous four-wave mixing.

In the lab

“We injected the beam into two regions on the chip (these regions subsequently become the two sources) and combined the quantum light produced using a beam-splitting element, also on the chip,” said Bristol team member Josh Silverstone. “We precisely controlled the path length travelled by the photons through one of the sources by changing the temperature of one of the two waveguides contained in the chip and observed quantum interference fringes.” These fringes are a signature pattern of two-photon quantum interference, he says.

A big advantage of silicon quantum photonics is that these structures can be fabricated using methods that are very similar to those used to make modern CMOS microelectronics, Thompson says. “Our particular circuits were made by Toshiba in Kawasaki, Japan, using standard silicon fabrication techniques, but any CMOS foundry could have been used. In the long term, we could even envisage quantum photons and standard electronics integrated on a single chip.”

Exceptionally well matched

Thanks to its circuit, the team was able to examine quantum interference between two on-chip photon sources for the first time. The sources show extremely high quantum interference, which implies that they are exceptionally well matched. “Such good matching is a prerequisite for building any larger scale quantum-optical system,” says Thompson.

Future chip

The circuit made in this work could also be used to perform more complex on-chip quantum optics experiments than those possible in bulk or fibre optics. “There are even wider implications for the future, however, in that many photon pair sources might be combined on individual silicon chips and work together in a highly efficient way,” adds Thompson.

The team, which includes researchers from the University of Glasgow in Scotland and the Kavli Institute of Nanoscience at Delft University of Technology in the Netherlands, now plans to combine the elements needed to make fully integrated photonic quantum information systems on a single device. “So far, we have combined quantum sources with quantum circuits, but the next big challenge will be to include single photon detectors, and then scale up to the many hundreds of on-chip components required to perform complex quantum information processing tasks with photons,” reveals Thompson.

14 new gene targets in Alzheimer’s identified.

Scientists have identified 14 new genes potentially implicated in Alzheimer’s disease.One gene in particular demonstrates the important role inflammation may play in the brain of Alzheimer’s patients, researchers who successfully generated a stem cell model of familial Alzheimer’s disease (FAD), have found.A team of scientists at The New York Stem Cell Foundation (NYSCF) Research Institute and the Icahn School of Medicine at Mount Sinai (ISMMS) produced stem cells and neural precursor cells (NPCs), representing early neural progenitor cells that build the brain from patients with severe early-onset AD with mutations in the Presenilin 1 (PSEN1) gene.These NPCs had elevated Abeta42/Abeta40 ratios, indicating elevation of the form of amyloid found in the brains of Alzheimer’s patients.These levels were greater than those in adult cells that did not have the PSEN1 mutation. This elevated ratio shows that the NPCs grown in the petri dish accurately reflected the cells in the brains of FAD patients.

“The gene expression profile from the familial Alzheimer’s stem cells points to inflammation, which is especially exciting because we would not usually associate inflammation with this particular Alzheimer’s gene,” said Sam Gandy, co-author on the study.

The researchers generated induced pluripotent stem (iPS) cells from affected and unaffected individuals from two families carrying PSEN1 mutations.

After thorough characterisation of the NPCs through gene expression profiling and other methods, they identified 14 genes that behaved differently in PSEN1 NPCs relative to NPCs from individuals without the mutation.

Five of these targets also showed differential expression in late onset Alzheimer’s disease patients’ brains.

Therefore, in the PSEN1 iPS cell model, the researchers reconstituted an essential feature in the molecular development of familial Alzheimer’s disease.

Source: PLOS ONE.

New blood test could be used to predict if a patient will have a heart attack.

Patients who suffer heart attacks have unique cells present in their blood, according to a new study.

The “significant” findings published in the journal “Physical Biology” could potentially be used to predict whether a patient is about to have a heart attack by testing for circulating endothelial cells (CECs).

As one person in the UK dies from a heart attack every seven minutes, the test is potentially life-saving if used by doctors.

Over a 100,000 heart attacks a year in the UK are caused by the build-up of fatty plaque on the walls of a person’s blood vessels.

If this wall breaks, plaque can be released into the bloodstream: blocking the blood-flow into vessels around the heart.

However, researchers at the Scripps Research Institute in California have discovered that CECs were also released into a patient’s blood.

The study assessed 79 patients who had suffered a heart attack, 25 who were healthy, and seven who were receiving treatment for diseased blood vessels.

Scientists concluded that the presence of CECs in a person’s blood after a heart attack was something not seen in healthy controls.

Prof Peter Kuhn, who worked on the project, explained that the results of the study are “so significant” that the next step is to establish how the findings can be used to identify patients during the early stages of a heart attack.

He added: “There are plenty of other ways to suggest that you are at long-term risk of a heart attack and there are good ways of diagnosing that you have just had a heart attack but what we don’t have is the ability to say ‘you will very likely have a heart attack in the next three weeks and we need to do something about this now’.”

However, Dr Mike Knapton of the British Heart Foundation, said: “In the short to medium term, it is unlikely to change how people in the UK are treated as we already have good ways to treat and diagnose heart attacks, and targets to ensure rapid pain-to-treatment times.

“This study appears to be laying the groundwork for future research to see if this test could be used to identify patients in the early stages of a heart attack.”

Lab-made bone marrow may lead to leukaemia cure.

Researchers in Germany have created a prototype of human-like bone marrow that could be used to produce blood-producing stem cells to facilitate leukaemia therapy. The breakthrough , by scientists at the Max Planck Institute for Intelligent Systems in Stuttgart , could pave the way for producing artificial stem cells and treatment of leukaemia in 10 to 15 years.

The lab-made bone marrow shows all major properties of natural marrow and could facilitate study of interaction between artificial materials and stem cells. This will help ascertain how the behaviour of stem cells is influenced by the artificial materials.

Using synthetic polymers , the scientists fashioned a porous structure simulating the sponge-like make-up of bone. They added proteinbuilding blocks similar to those found in the bone marrow matrix to anchor cells.

Hematopoietic (or bloodproducing ) stem cells, which had been isolated from cord blood, were introduced into the artificial bone marrow. After a few days, the cells were found to reproduce in the artificial bone marrow. Compared to standard cell cultivation methods, more stem cells were found to retain their properties in the lab-made marrow.

Blood cells, such as red or white blood cells, are continuously replaced by new ones created by the blood-producing stem cells found in a specialized niche of the marrow . This makes the stem cells ideal for treatment of blood diseases such as leukaemia . The affected cells of the patient are replaced by healthy hematopoietic stem cells from a donor.

Ultrasound can boost sensory performance: Study

Ultrasound can boost sensory performance: Study
Scientists at Virginia Tech Carilion Research Institute have demonstrated that ultrasound directed to a specific region of the brain can boost performance in sensory discrimination.

Ultrasound can modulate brain activity to heighten sensory perception in humans, says a study.

Scientists at Virginia Tech Carilion Research Institute have demonstrated that ultrasound directed to a specific region of the brain can boost performance in sensory discrimination.The study provides the first demonstration that low-intensity, transcranial-focused ultrasound can modulate human brain activity to enhance perception.

“Ultrasound has great potential for bringing unprecedented resolution to the growing trend of mapping the human brain’s connectivity,” said William ‘Jamie’ Tyler, assistant professor at Virginia Tech Carilion Research Institute.

“So we decided to look at the effects of ultrasound on the region of the brain responsible for processing tactile sensory inputs,” he said.

The scientists delivered focused ultrasound to an area of the cerebral cortex that processes sensory information received from the hand, said the study published in Nature Neuroscience.

To stimulate the median nerve – a major nerve that runs down the arm and the only one that passes through the carpal tunnel – they placed a small electrode on the wrist of human volunteers and recorded their brain responses using electroencephalography, or EEG.

Then, just before stimulating the nerve, they began delivering ultrasound to the targeted brain region.

The scientists found that the ultrasound both decreased the EEG signal and weakened the brain waves responsible for encoding tactile stimulation.

The scientists then administered two classic neurological tests – the two-point discrimination test that measures a subject’s ability to distinguish whether two nearby objects touching the skin are truly two distinct points, rather than one.

The second is the frequency discrimination task – a test that measures sensitivity to the frequency of a chain of air puffs.

They found unexpected results.

The subjects receiving ultrasound showed significant improvements in their ability to distinguish pins at closer distances and to discriminate small frequency differences between successive air puffs.

“Even though the brain waves associated with the tactile stimulation had weakened, people actually got better at detecting differences in sensations,” said Tyler, adding that the ultrasound affected an important neurological balance.

“We believe focused ultrasound changed the balance of ongoing excitation and inhibition processing sensory stimuli in the brain region, resulting in a functional improvement in perception, he added.

“This approach can be used for potential treatments of neurodegenerative disorders, psychiatric diseases and behavioural disorders, the study said.

UK engineer gives new theory on how pyramids were built.

A file photo of the historical site of the Giza Pyramids near Cairo, Egypt.
AP A file photo of the historical site of the Giza Pyramids near Cairo, Egypt.

Ancient Egyptians created pyramids by piling up rubble on the inside and attaching bricks on the outside later, according to a new theory proposed by a British engineer.

Peter James, an engineer at Cintec International in Newport, South Wales, has stunned archaeologists by claiming their theories on how pyramids were built are wrong.

According to the currently accepted belief, pyramids were built with giant blocks carried up huge ramps.

James said such a thing would be impossible as the ramps would have had to have been at least a quarter of a mile long to get the right angle for the bricks to be taken to such great heights, ‘Mirror Online’ reported.

“Under the current theories, to lay the two million stone blocks required the Egyptians would had to have laid a large block once every three minutes on long ramps,” said Mr. James, who has spent the past 20 years studying pyramids.

“If that happened, there would still be signs that the ramps had been there, and there aren’t any,” he said.

Mr. James has assisted in reinforcing burial chambers in the 4,600-year-old Step Pyramid and the Red Pyramid.

According to ‘’, inside the Step pyramid in Egypt, his team discovered that a massive tonnage of small stones was being held up only by the trunk of a palm tree thousands of years old.

The engineer believes that the inside of the pyramids are made of small, easily handled blocks and that they were built from the inside out — not the outside in.

Fruit juice not a healthy option: UK expert.

If you are going to drink fruit juice, you should dilute it, says Susan Jebb, head of diet and obesity research at the Medical Research Council’s Human Nutrition Research unit in Cambridge. File photo: V.V. Krishnan
The Hindu If you are going to drink fruit juice, you should dilute it, says Susan Jebb, head of diet and obesity research at the Medical Research Council’s Human Nutrition Research unit in Cambridge.Fruit juice should be removed from the recommended list of five-a-day portions of fruit or vegetables in the U.K. as it contained as much sugar as many soft drinks, an adviser to the government on obesity has said.

Susan Jebb, head of diet and obesity research at the Medical Research Council’s Human Nutrition Research unit in Cambridge, said she did not see juice as a healthy option.

“I would support taking it out of the five-a-day guidance,” she said.

“Fruit juice isn’t the same as intact fruit and it has got as much sugar as many classical sugar drinks. It is also absorbed very fast so by the time it gets to your stomach your body doesn’t know whether it’s Coca-Cola or orange juice, frankly,” she told Sunday Times.

“I have to say it is a relatively easy thing to give up. Swap it and have a piece of real fruit. If you are going to drink it, you should dilute it,” she said.

Ms. Jebb said she had herself stopped drinking orange juice and advised others to do so, or at least drink it diluted.

The paper quoted her as saying she would support a wider tax on sugar-heavy drinks.

Ms. Jebb works closely with the U.K. government on diet and obesity issues, and leads the government’s so-called health responsibility deal, which oversees voluntary pledges by the food and drink industry to improve public health.

Her comments follow a similar warning in September by two U.S. scientists, Barry Popkin and George Bray, who exposed the health risks of fructose corn syrup in soft drinks in 2004.

Popkin, a professor of nutrition at the University of North Carolina, told the Guardian that fruit juices and fruit smoothies were “the new danger”.

“Think of eating one orange or two and getting filled. Now think of drinking a smoothie with six oranges and two hours later it does not affect how much you eat. The entire literature shows that we feel full from drinking beverages like smoothies but it does not affect our overall food intake, whereas eating an orange does,” he said.

“So pulped-up smoothies do nothing good for us but do give us the same amount of sugar as four to six oranges or a large coke. It is deceiving,” Mr. Popkin said.

Will Mozart make my child smarter?

Will Mozart make my child smarter?

Black hole to ‘eat biggest meal’.

If the black hole “bites” the gas cloud, X-ray “fireworks” will flare out

Astronomers are getting ready for their best ever glimpse of the mysterious black hole at the heart of our galaxy.

“Fireworks” will flare if it gobbles up a giant gas cloud which is drifting perilously close.

A collision is now likely in spring, according to scientists at the American Astronomical Society meeting.

Stargazers will be able to see the climax on a new public monitoring website.

“This could be our black hole’s biggest meal in hundreds of years,” said Leo Meyer, of the University of California, Los Angeles.

“It might bring spectacular fireworks – and we want everybody to watch.”

Front row seats

The collision could give astronomers a unique window on one of the universe’s great enigmas.

Black holes are so dense that not even light can escape them, once it passes their event horizon (point of no return).

The heart of our Milky Way galaxy - a seven-year-long X-ray by Swift.
The heart of our Milky Way galaxy – a seven-year-long X-ray by Swift. The black hole is hidden in the centre

They can only be observed indirectly – from brief flashes of radiation released by matter falling in.

The giant gas cloud G2 is three times the mass of Earth. It was first spotted in 2011 hurtling towards Sagittarius A* – the black hole in our galactic core.

Impact is now just a few months away. If the gas drifts close enough it will heat up, releasing great flares of X-rays, which shed light on the black hole’s properties.

Astronomers have already secured front row seats. Dr Meyer’s team is tracking the cloud’s approach using the Keck Observatory in Hawaii.

They can see it “stretching like spaghetti” as the black hole tugs at its head, now moving much faster than its tail.

A gas cloud being 'stretched like spaghetti' by the black hole's gravity The gas cloud is being ‘stretched like spaghetti’ by the black hole’s gravity

And while Keck watches the cloud, Swift is watching the black hole. Nasa’s X-Ray space telescope is poised and primed to catch the first glimmers of an encounter.


“Everyone wants to see the event happening because it’s so rare,” said Nathalie Degenaar, Swift’s principal investigator.

Sagittarius A* lurks 26,000 light years away in the Milky Way’s innermost region.

Viewed from Earth, it is in the southern summer sky near the constellations Sagittarius and Scorpius.

Black holes

Artist's impression, supermassive black hole
  • Black holes are incredibly dense objects with gravity strong enough to trap even light
  • A ‘medium’ black hole could have the mass of 1,000 Suns but be no bigger than Earth
  • Supermassive black holes are thought to be at the centre of most large galaxies – including ours

Even for a black hole it is dim – about a billion times fainter than others of its “supermassive” type.

And this makes it something of a mystery.

“Currently it’s not easy to see at all. But if the gas cloud suddenly feeds it with much more mass, you might get fireworks. And with that, you can test all sorts of theories,” said Dr Meyer.

Black holes are thought to play a crucial role in the life cycles of galaxies.

They eat matter from their surroundings and blow matter back. This influences how stars are formed, how the galaxy grows, and how it interacts with other galaxies.

To get a sense of the typical feeding habits of Sagittarius A*, the Swift team has been making regular observations since 2006.

Every few days, their spacecraft turns toward the galaxy’s core and takes a 17-minute-long exposure.

To date, they have detected six strong flares where the black hole was 150 times brighter for a couple of hours. But these are mere flickers compared to the jets that could erupt from G2 – the display could last for years.

Big dinner date

Exactly how dramatic it transpires to be depends on what’s inside the cloud.

If it is mostly hydrogen gas, the X-rays will glow for years to come as the black hole slowly swallows it.

The cloud was spotted in 2011 hurtling towards the galactic core
The cloud was spotted in 2011 hurtling towards the galactic core.

But there is another possibility – the cloud could be hiding an old star. In which case, the big dinner date could be an anticlimax.

The black hole may slurp a little from the cloud while the star slips on by at a safe distance, dense enough to escape its gravity.

“I would be delighted if Sagittarius A* suddenly became 10,000 times brighter. However it’s possible it will not react much – like a horse that won’t drink when led to water,” said Jon Miller, of the University of Michigan.

“Will there be fireworks or not? We have to wait and see. There is no smoking gun that can tell us yet,” said Dr Meyer.

“But even if the odds are against it, you still have to look, because if you do see something it could be spectacular.”