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31

Astronomy / Supernova 'dust factory' pictured

« on: August 05, 2014, 06:28:41 PM »

Striking images of a young supernova brimming with fresh dust have been captured by a telescope in the Chilean desert.

It is the first time astronomers have witnessed the genesis of the grains which formed galaxies in the early universe.

The pictures were captured by the Alma (Atacama Large Millimeter/submillimeter Array) telescope.

They were revealed at the 223rd meeting of the American Astronomical Society.

They will be published in the Astrophysical Journal Letters.

Fading giants
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Space is quite a messy place”

Remy Indebetouw
Astronomer
The universe is full of tiny solid particles – from the dark bands we see in the Milky Way to the beautiful clouds in iconic pictures from the Hubble telescope.

Dust collapses into planets and aids the formation of stars. But despite its ubiquity, there was no firm evidence of where it actually emerged from in the first place.

In today's universe, it largely forms around dying stars as they burn out. But these fading giants were not around at the dawn of the universe.

“It's the same problem as we have in my house – there's a lot of dust and we don't know where it comes from. Space is quite a messy place," quipped Remy Indebetouw, an astronomer with the National Radio Astronomy Observatory.

“So we took one of the most technologically advanced telescopes ever – Alma – and tried to find out how dust formed in the early universe.”

"Supernovas have long been thought to be the creators – the bright factories that burst out building blocks for galaxies. But catching one in the act is far from easy.

"And even when we do spot a supernova cloaked in a dusty plume, there's the old chicken-egg problem: how do we know that the cloud wasn't there first?”

'Not a nuisance'
To settle the argument, a team of astronomers from the UK and US used Alma to observe the glowing remains of 1987A, the closest recently observed supernova, 168,000 light-years from Earth.

They predicted that, as the gas cooled after the explosion, solid molecules would form in the centre from atoms of oxygen, carbon, and silicon bonded together.

Earlier observations of 1987A with the infrared telescope Herschel had only detected a small amount of hot dust.

But thanks to the power of the Alma radio telescope array, which stretches out over the Atacama desert, it took only 20 minutes to capture the evidence on camera.

“We found a remarkably large dust mass concentrated in the central part of the ejecta [cloud of particles],” said Dr Indebetouw.

Supernova 1987A
The data from Alma was combined with observations by Nasa's Hubble and Chandra telescopes to create this supernova image
“And all of that matter – the red area you see at the centre of the picture – was there in the core of the star before it exploded.That's the exciting thing.

“People think of dust as a nuisance - something that gets in your way. But it turns out it's pretty important.”

While supernovae signal the destruction of stars, they are also the source of new material and energy, says Dr Jacco van Loon of Keele University, a co-author on the study.

“Our lives would be very different without the chemical elements that were synthesised in supernovae throughout history,” he said.

“Grains are incredibly difficult to make in the vast emptiness of space. And if supernovae indeed make lots of them, this has very important and positive consequences for the eventual formation of the Sun and the Earth.”

Alma Observatory graphic

32

Astronomy / Deepest galaxy cluster ever pictured by Hubble

« on: August 05, 2014, 06:27:55 PM »

The "deepest ever" image of a group of galaxies - "Pandora's Cluster" - has been captured by the Hubble Space Telescope.

The blue arcs in the picture are distant galaxies as they appeared 12 billion years ago - not long after the Big Bang.

The hidden objects are revealed through the "magnifying lens" of the cluster Abell 2744.

The image was unveiled at the 223rd meeting of the American Astronomical Society (AAS) in Washington DC.

It is the first in a set of super-deep views of the Universe taken by Hubble's Frontier Fields observing programme, and published on the Arxiv preprint server.

Funhouse mirror
In the foreground are the colourful spirals and elliptical galaxies of Abell 2744, a massive cluster in the constellation Sculptor.

It is nicknamed Pandora for its strange and violent formation history, which unleashed many new phenomena to astronomers.

Galaxy GN-z10-1
One of the earliest galaxies ever seen - as it appeared 13.2 billion years ago
Abell's immense gravity acts as a lens to warp, brighten and magnify more distant objects lurking in the background.

The long exposure by Hubble reveals almost 3,000 of these background galaxies, interwoven with hundreds in the foreground.

The faintest is 10-20 times fainter than any galaxy ever seen before.

They appear brighter thanks to the lensing phenomenon, but are also smeared, stretched and duplicated - like faces in a funhouse mirror.

The remarkable photograph will be combined with images from Nasa's Spitzer telescope and Chandra X-ray Observatory to give new insights into the origin of galaxies and their accompanying black holes.

It was one of three spectacular new findings by Hubble unveiled at the AAS conference.

Four brilliant young galaxies have been pictured as they were 13.2 billion years ago - just 500 million years after the Big Bang.

The brightest was forming stars 50 times faster than our Milky Way does today, but is only one twentieth the size.

Abell 1689
These previously unseen galaxies gave birth to most stars in the cosmos today
Although Hubble has previously identified galaxies at this early epoch, astronomers were surprised to find objects 10 to 20 times more luminous than anything seen before.

"These just stuck out like a sore thumb because they are far brighter than we anticipated," said Garth Illingworth of the University of California at Santa Cruz.

"There are strange things happening... we're suddenly seeing luminous, massive galaxies quickly build up at such an early time. This was quite unexpected."

For the first time, the astronomers were able to estimate the masses of these early galaxies, by using Spitzer to measure their total luminosity.

"They were much larger than we expected to find. Only 1% of our Milky Way. But that is a big galaxy for that early era," said Dr Illingworth.

The discovery of such rich activity at the extreme limits of Hubble's range bodes well for Nasa's James Webb Space Telescope (JWST), currently in development.

3D printed galaxy
3D printing brings Hubble's spectacular images to life for the visually impaired
JWST would allow astronomers to look even farther back in time to see some of the first galaxies ever made in the Universe.

"We're reaching back through 96% of the life of the Universe to these galaxies - that's an astonishing undertaking. And with James Webb, we can learn even more," said Dr Illingworth.

Another new striking image released from Hubble features the "unseen" galaxies thought to be responsible for the "baby boom" that created most stars we see today.

Deep exposures in ultraviolet light, made with Hubble's Wide Field Camera 3, revealed a sample of 58 small, faint galaxies that existed more than 10 billion years ago.

Normally too dim for Hubble to see, these galaxies were revealed through gravitational lensing focused on the massive cluster Abell 1689 in the constellation Ursa Major.

"There's always been a concern that we've only found the brightest of the distant galaxies - the tip of the iceberg," said Brian Siana of the University of California at Riverside.

"We believe most stars forming in the early Universe occur in galaxies we normally can't see at all. Now we have found those 'unseen' galaxies, and we're really confident we're seeing the rest of the iceberg."

A new project to bring these stunning images to life for the blind and visually impaired was unveiled at the AAS meeting: 3D printed galaxies - with different textures for dust clouds, nebulae and other celestial features.

"The visually impaired can now explore and appreciate the beauty of Hubble images through touch," said Carol Christian, of the Space Telescope Science Institute.

"Our ultimate goal - anyone who would like to hold a piece of the Universe in their hands can get the data from Hubble and print them in their school, library, or their home."

33

Astronomy / Cosmic 'web' seen for first time

« on: August 05, 2014, 06:27:29 PM »

The hidden tendrils of dark matter that underlie the visible Universe may have been traced out for the first time.

Cosmology theory predicts that galaxies are embedded in a cosmic web of "stuff", most of which is dark matter.

Astronomers obtained the first direct images of a part of this network, by exploiting the fact that a luminous object called a quasar can act as a natural "cosmic flashlight".

Details of the work appear in the journal Nature.

The quasar illuminates a nearby gas cloud measuring two million light-years across.

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In this case we were lucky that the flashlight is pointing toward the nebula and making the gas glow”

Sebastiano Cantalupo
University of California, Santa Cruz
And the glowing gas appears to trace out filaments of underlying dark matter.

The quasar, which lies 10 billion light-years away, shines light in just the right direction to reveal the cold gas cloud.

For some years, cosmologists have been running computer simulations of the structure of the universe to build the "standard model of cosmology".

They use the cosmic microwave background, corresponding to observations of the very earliest Universe that can be seen, and recorded by instruments such as the Planck space observatory, as a starting point.

Their calculations suggest that as the Universe grows and forms, matter becomes clustered in filaments and nodes under the force of gravity, like a giant cosmic web.

The new results from the 10-metre Keck telescope in Hawaii, are reported by scientists from the University of California, Santa Cruz and the Max Planck Institute for Astronomy in Heidelberg.

They are the first direct observations of cold gas decorating such cosmic web filaments.

UM 287 quasar and gas
The observed portion of the cosmic web (cyan) is about 2 million light-years across
The cosmic web suggested by the standard model is mainly made up of mysterious "dark matter". Invisible in itself, dark matter still exerts gravitational forces on visible light and ordinary matter nearby.

Massive clumps of dark matter bend light that passes close by through a process called gravitational lensing, and this had allowed previous measurements of its distribution.

But it is difficult to use this method to see very distant dark matter, and cold ordinary matter remains tricky to detect as well.

The glowing hydrogen illuminated by the distant quasar in these new observations traces out an underlying filament of dark matter that it is attracted to it by gravity, according to the researchers' analysis.

"This is a new way to detect filaments. It seems that they have a very bright quasar in a rare geometry," Prof Alexandre Refregier of the ETH Zurich, who was not involved in the work, told BBC News.

"If indeed gravity is doing the work in an expanding Universe, we expect to see a cosmic web and it is important to detect this cosmic web structure."

In the dark
He added: "What is expected is that the dark matter dominates the mass and forms these structures, and then the ordinary matter, the gas, the stars and everything else trace the filaments and structures that are defined by the dynamics of the dark matter."

"Filaments have been detected indirectly before using gravitational lensing, which allows us to see the distribution of the dark matter.

"Part of the ordinary matter has formed stars, which we can see, but another component is the gas. If the gas is very hot it emits X-rays and can be seen using X-ray telescopes. Other techniques to detect cooler gas now include the method described here."

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Dark energy and dark matter mysteries

Lux dark matter detector
Gravity acting across vast distances does not seem to explain what astronomers see
Galaxies, for example, should fly apart; some other mass must be there holding them together
Astrophysicists have thus postulated "dark matter" - invisible to us but clearly acting on galactic scales
At the greatest distances, the Universe's expansion is accelerating
Thus we have also "dark energy" which acts to drive the expansion, in opposition to gravity
The current theory holds that 68% of the Universe is dark energy, 27% is dark matter, and just 5% the kind of matter we know well
How close are we to finding dark matter?
Sebastiano Cantalupo, lead author of the article, and others have used the same method previously to look for glowing gas around quasars, and had seen dark galaxies.

"The dark galaxies are much denser and smaller parts of the cosmic web. In this new image, we also see dark galaxies, in addition to the much more diffuse and extended nebula," Dr Cantalupo, from UCSC, explained.

"Some of this gas will fall into galaxies, but most of it will remain diffuse and never form stars.

"The light from the quasar is like a flashlight beam, and in this case we were lucky that the flashlight is pointing toward the nebula and making the gas glow. We think this is part of a filament that may be even more extended than this, but we only see the part of the filament that is illuminated by the beamed emission from the quasar."

While the observations support the cosmological simulations' general picture of a cosmic web of filamentary structures, the researchers' results suggest around 10 times more gas in the nebula than predicted from typical computer simulations.

They postulate that this may simply be due to limitations in the spatial resolution of the current models, or, more interestingly perhaps, may be because the current grid-based models are missing some aspect of the underlying physics of how galaxies form, evolve, and interact with quasars.

"We now have very precise measurements of the amount of ordinary matter and dark matter in the Universe," said Prof Refregier.

"We can only observe a fraction of the ordinary matter, so the question is what form the remainder takes. These results may imply that a lot of it is in the form detected here."

34

Astronomy / Astronomers weigh up Milky Way

« on: August 05, 2014, 06:26:38 PM »

The Milky Way is lighter than astronomers previously thought, researchers have concluded.

A team of scientists led by the University of Edinburgh found it has about half the mass of a neighbouring galaxy, known as Andromeda.

Their estimates come from working out the mass of invisible matter found in the outer regions of both galaxies.

They concluded that dark matter accounted for Andromeda's extra weight.

Dark matter is a little-understood invisible substance which makes up most of the outer regions of galaxies.

The researchers have estimated that Andromeda contains twice as much dark matter as the Milky Way, causing it to be twice as heavy.

The Milky Way and Andromeda have similar structures and are the two largest in a region of galaxies which astronomers call the Local Group.

The researchers say their work should help them learn more about how the outer regions of galaxies are structured.

Andromeda Galaxy
The researchers concluded that Andromeda contains twice as much dark matter as the Milky Way
According to the research group, previous studies were only able to measure the mass enclosed within both galaxies' inner regions.

Dr Jorge Penarrubia, of the University of Edinburgh's School of Physics and Astronomy, who led the study, said: "We always suspected that Andromeda is more massive than the Milky Way, but weighting both galaxies simultaneously proved to be extremely challenging.

"Our study combined recent measurements of the relative motion between our galaxy and Andromeda with the largest catalogue of nearby galaxies ever compiled to make this possible."

The study, published in the journal Monthly Notices of the Royal Astronomical Society, was carried out in collaboration with the University of British Columbia, Carnegie Mellon University and NRC Herzberg Institute of Astrophysics.

The work was supported by the UK's Science and Technology Facilities Council.

35

Natural Science / How facial features drive our first impressions

« on: August 05, 2014, 06:26:04 PM »

Whether it's a curled lip or a keen cheekbone, we all make quick social judgements based on strangers' faces.

Now scientists have modelled the specific physical attributes that underpin our first impressions.

Small changes in the dimensions of a face can make it appear more trustworthy, dominant or attractive.

The results, published in the journal PNAS, could help film animators or anyone looking to create an instant impression on a social network.

Dr Tom Hartley, a neuroscientist at the University of York and the study's senior author, said the work added mathematical detail to a well-known phenomenon.

"If people are forming these first impressions, just based on looking at somebody's face, what is it about the image of the face that's giving that impression - can we measure it exactly?"

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Three key dimensions of a first impression

Approachability: how likely is this person to help (or hinder) me?
Dominance: how capable is this person of carrying out those intentions?
Attractiveness: is this person young and good looking - a potential romantic partner?
Positive first impressions are especially important in a world dominated by social media, from LinkedIn to Tinder.

Dr Hartley sees the commercial potential in applying his numerical model to the photos people use to present themselves online. "It's obviously potentially very useful," he told the BBC.

To make the calculations, each of 1,000 face photos from the internet was shown to at least six different people, who gave it a score for 16 different social traits, like trustworthiness or intelligence.

Overall, these scores boil down to three main characteristics: whether a face is (a) approachable, (b) dominant, and (c) attractive.

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Cartoon faces based on the new mathematical model, sliding along 3 scales: approachability, dominance and attractiveness
By measuring the physical attributes of all 1,000 faces and putting them together with those scores, Dr Hartley and his team built a mathematical model of how the dimensions of a face produce those three impressions.

The next step was to get the computer to extrapolate. Using their new model, the team produced cartoon versions of the most (and least) approachable, dominant and attractive faces - as well as all the possibilities in between.

Example faces
Six faces and their computerised approximations, including study author Dr Tom Hartley (second from left)
John Humphrys
The same treatment given to the Today programme's John Humphrys
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You could use these kind of numbers to decide when is a good time to take a photograph, or to choose the photograph that's really optimal in putting forward the best possible impression”

Dr Tom Hartley
University of York
Finally, and most importantly, these cartoon results could be tested. When the researchers quizzed more participants about their impressions of the artificial, cartoon faces, the ratings matched. People said that the computer's cartoon prediction of an approachable face was, indeed, approachable - and so on.

So has all this work revealed humanity's ultimate trustworthy jawline, or the most assertive shape for eyebrows? Dr Hartley is cautious.

"Lots of the features of the face tend to vary together," he explained. "So it's very difficult for us to pin down with certainty that a given feature of the face is contributing to a certain social impression."

There are some obvious trends however - including the tendency for masculine faces to be perceived as dominant, or for a broadly smiling face to seem more approachable and trustworthy.

This points to a potentially worrying implication: brief facial expressions can make a big difference to how we are received by strangers.

"It might be problematic if we're forming these kind of judgements based on these rather fleeting impressions," Dr Hartley said, "particularly in today's world where we only might see one picture of a face, on social media, and have to form our impression based on that."

Cartoon faces
A mathematical model produced cartoon faces based on how people rated various facial dimensions
On the other hand, the findings could help people put their best face forward.

"It might be very useful for organisations who are interested in people's faces," said Dr Hartley.

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[Being] approachable is tied to smiling expressions and unapproachable to frowning or angry expressions, while dominance is tied to masculine features”

Dr Anthony Little
University of Stirling
That might include interests as diverse as photographers, Facebook and Pixar.

"You would be able to use these kind of numbers to decide when is a good time to take a photograph, or maybe to choose the photograph that's really optimal in putting forward the best possible impression - and you might want to put forward different kinds of social impressions in different situations."

Animators, on the other hand, "have to give life, and give some social meaning, to the faces of their characters just by changing small things," Dr Hartley said.

"What we're doing is trying to put that on a scientific footing. It's been fascinating to find out more about it."

Dr Anthony Little, a reader in psychology at the University of Stirling, said the findings point to something "simple and important" about the way physical attributes guide our social responses.

Silly face
Impressions included attractiveness and trustworthiness - potential mate or used car salesman?
"The results highlight that the way we see other people may be in relatively simple terms, as approachable/unapproachable and dominant/submissive," said Dr Little, whose own research on faces and psychology includes using a website to crowd-source ratings.

"Each of these two factors looks to be tied to specific face features. So, approachable is tied to smiling expressions and unapproachable to frowning or angry expressions, while dominance is tied to masculine features.

"The third factor, youthful-attractiveness, appears less distinct."

This is because of interplay between attractiveness and the other two factors, Dr Little explained.

36

Natural Science / Quantum computing device hints at powerful future

« on: August 05, 2014, 06:24:59 PM »

One of the most complex efforts toward a quantum computer has been shown off at the American Physical Society meeting in Dallas in the US.

It uses the strange "quantum states" of matter to perform calculations in a way that, if scaled up, could vastly outperform conventional computers.

The 6mm-by-6mm chip holds nine quantum devices, among them four "quantum bits" that do the calculations.

The team said further scaling up to 10 qubits should be possible this year.

Rather than the ones and zeroes of digital computing, quantum computers deal in what are known as superpositions - states of matter that can be thought of as both one and zero at once.

In a sense, quantum computing's one trick is to perform calculations on all superposition states at once. With one quantum bit, or qubit, the difference is not great, but the effect scales rapidly as the number of qubits rises.

The figure often touted as the number of qubits that would bring quantum computing into a competitive regime is about 100, so each jump in the race is a significant one.

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We're right at the bleeding edge of actually having a quantum processor”

Erik Lucero
University of California, Santa Barbara
"It's pretty exciting we're now at a point that we can start talking about what the architecture is we're going to use if we make a quantum processor," Erik Lucero of the University of California, Santa Barbara told the conference.

The team's key innovation was to find a way to completely disconnect - or "decouple" - interactions between the elements of their quantum circuit.

The delicate quantum states the team creates in their qubits - in this case paired superconductors known as Josephson junctions - must be manipulated, moved, and stored without destroying them.

"It's a problem I've been thinking about for three or four years now, how to turn off the interactions," UCSB's John Martinis, who led the research," told BBC News.

"Now we've solved it, and that's great - but there's many other things we have to do."

Qubits and pieces
The solution came in the form of what the team has termed the RezQu architecture. It is basically a blueprint for a quantum computer, and several presentations at the conference focused on how to make use of it.

"For me this is kind of nice, I know how I'm going to put them together," said Professor Martinis.

"I now know how to design it globally and I can go back and try to optimise all the parts."

RezQu seems to have an edge in one crucial arena - scalability - that makes it a good candidate for the far more complex circuits that would constitute a quantum computer proper.

"There are competing architectures, like ion traps - trapping ions with lasers, but the complexity there is that you have to have a huge room full of PhDs just to run your lasers," Mr Lucero told BBC News.

Quantum bit and resonator on a chip (E Lucero)
The team has been steadily increasing the complexity of their quantum devices
"There's already promise to show how this architecture could scale, and we've created custom electronics based on cellphone technology which has driven the cost down a lot.

"We're right at the bleeding edge of actually having a quantum processor," he said. "It's been years that a whole community has blossomed just looking at the idea of, once we have a quantum computer, what are we going to do with it?"

Britton Plourde, a quantum computing researcher from the University of Syracuse, said that the field has progressed markedly in recent years.

The metric of interest to quantum computing is how long the delicate quantum states can be preserved, and Dr Plourde noted that time had increased a thousand fold since the field's inception.

"The world of superconducting quantum bits didn't even exist 10 years ago, and now they can control [these states] to almost arbitrary precision," he told BBC News.

"We're still a long way from a large-scale quantum computer but it's really in my eyes rapid progress."

37

Natural Science / Quantum computing device hints at powerful future

« on: August 05, 2014, 06:24:48 PM »

One of the most complex efforts toward a quantum computer has been shown off at the American Physical Society meeting in Dallas in the US.

It uses the strange "quantum states" of matter to perform calculations in a way that, if scaled up, could vastly outperform conventional computers.

The 6mm-by-6mm chip holds nine quantum devices, among them four "quantum bits" that do the calculations.

The team said further scaling up to 10 qubits should be possible this year.

Rather than the ones and zeroes of digital computing, quantum computers deal in what are known as superpositions - states of matter that can be thought of as both one and zero at once.

In a sense, quantum computing's one trick is to perform calculations on all superposition states at once. With one quantum bit, or qubit, the difference is not great, but the effect scales rapidly as the number of qubits rises.

The figure often touted as the number of qubits that would bring quantum computing into a competitive regime is about 100, so each jump in the race is a significant one.

Continue reading the main story
“
Start Quote

We're right at the bleeding edge of actually having a quantum processor”

Erik Lucero
University of California, Santa Barbara
"It's pretty exciting we're now at a point that we can start talking about what the architecture is we're going to use if we make a quantum processor," Erik Lucero of the University of California, Santa Barbara told the conference.

The team's key innovation was to find a way to completely disconnect - or "decouple" - interactions between the elements of their quantum circuit.

The delicate quantum states the team creates in their qubits - in this case paired superconductors known as Josephson junctions - must be manipulated, moved, and stored without destroying them.

"It's a problem I've been thinking about for three or four years now, how to turn off the interactions," UCSB's John Martinis, who led the research," told BBC News.

"Now we've solved it, and that's great - but there's many other things we have to do."

Qubits and pieces
The solution came in the form of what the team has termed the RezQu architecture. It is basically a blueprint for a quantum computer, and several presentations at the conference focused on how to make use of it.

"For me this is kind of nice, I know how I'm going to put them together," said Professor Martinis.

"I now know how to design it globally and I can go back and try to optimise all the parts."

RezQu seems to have an edge in one crucial arena - scalability - that makes it a good candidate for the far more complex circuits that would constitute a quantum computer proper.

"There are competing architectures, like ion traps - trapping ions with lasers, but the complexity there is that you have to have a huge room full of PhDs just to run your lasers," Mr Lucero told BBC News.

Quantum bit and resonator on a chip (E Lucero)
The team has been steadily increasing the complexity of their quantum devices
"There's already promise to show how this architecture could scale, and we've created custom electronics based on cellphone technology which has driven the cost down a lot.

"We're right at the bleeding edge of actually having a quantum processor," he said. "It's been years that a whole community has blossomed just looking at the idea of, once we have a quantum computer, what are we going to do with it?"

Britton Plourde, a quantum computing researcher from the University of Syracuse, said that the field has progressed markedly in recent years.

The metric of interest to quantum computing is how long the delicate quantum states can be preserved, and Dr Plourde noted that time had increased a thousand fold since the field's inception.

"The world of superconducting quantum bits didn't even exist 10 years ago, and now they can control [these states] to almost arbitrary precision," he told BBC News.

"We're still a long way from a large-scale quantum computer but it's really in my eyes rapid progress."

38

Natural Science / Quantum computing could head to 'the cloud', study says

« on: August 05, 2014, 06:23:28 PM »

A novel high-speed, high-security computing technology will be compatible with the "cloud computing" approach popular on the web, a study suggests.

Quantum computing will use the inherent uncertainties in quantum physics to carry out fast, complex computations.

A report in Science shows the trick can extend to "cloud" services such as Google Docs without loss of security.

This "blind quantum computing" can be carried out without a cloud computer ever knowing what the data is.

Quantum computing has been heralded as the most powerful potential successor to traditional, electronics-based computing.

One of the peculiarities of the branch of physics called quantum mechanics is that objects can be in more than one state at once, with the states of different objects tied together in ways that even Albert Einstein famously referred to as "spooky".

Instead of the 0 and 1 "bits" of digital computing, quantum computing aims to make use of these mixed and entangled states to perform calculations at comparatively breathtaking speeds.

Other quantum trickery comes in cryptography, the art of encrypting data. Data is encoded in delicately prepared states - most often those of single particles of light called photons - and the data cannot be "read" without destroying them.

Quantum cryptography uses this feature to send the "keys" to decrypting messages with high security.

However, the quantum computing approach is still in its formative stages, able to carry out only simple calculations - and quantum cryptography is, for the most part, limited to the laboratory setting.

The world in which both are accessible to consumers has seemed distant.

Cue bits
The new work, by University of Vienna quantum computing pioneer Anton Zeilinger and a team of international scientists, combines the two.

They show that future technology need only come up with a means of making quantum bits, or qubits, at home; the heavy lifting of quantum computing can then be done in the cloud completely securely.

Quantum cryptography setup in laboratory
Quantum computing and cryptography equipment is still for the most part restricted to laboratories
A user would send single qubits - each perfectly secure - to a remote computer, along with a recipe for the measurements to be made.

The process is completely clear to the user - for example, finding all the numbers that multiply together to reach the number 2,012 - but because the number 2,012 is encrypted, the instructions appear to be a series of random steps on an unknown number.

The remote computer blindly "entangles" the unknown bits, carries out the steps, and sends the qubits back down the line, solving the problem without ever decoding what is going on.

The team built a system demonstrating that the approach works, using a number of computational steps that might make up future computing scenarios.

Much remains to be developed for a cloud/quantum computing future - first of all, a means to create qubits at home, which could be done with existing technology if there were a consumer demand.

Long-distance quantum cryptography has already been demonstrated in a real-world application: the technology was put to use in elections in Switzerland in 2007 using a custom network of fibres.

More recently, researchers at University College Cork demonstrated that similar quantum information can be sent down the same fibres that bring broadband to many homes around the world.

What is still lacking, and preoccupying quantum physicists around the world, is the workhorse quantum computer itself.

The computer's complexity is steadily rising; results earlier this month suggest the juggling of some 84 qubits simultaneously.

As with the earliest days of more familiar computer technology, however, significant simplification, miniaturisation and a plunge in costs will be necessary before quantum computing becomes a resource in the cloud.

39

Natural Science / Quantum computing: Is it possible, and should you care?

« on: August 05, 2014, 06:22:52 PM »

What is a quantum computer and when can I have one? It makes use of all that "spooky" quantum stuff and vastly increases computing power, right? And they'll be under every desk when scientists finally tame the spooky stuff, right? And computing will undergo a revolution no less profound than the one that brought us the microchip, right?

Well, sort of.

That is broadly what has been said about quantum computers up to now, but it's probably best to pause here and be clear about what is, at this stage, most likely to come.

First things first, though: just what do they do? Many media outlets have dived into the academic literature sporadically to shed some light on the effort.

BBC News has reported that quantum computers "exploit the counterintuitive fact that photons or trapped atoms can exist in multiple states or 'superpositions' at the same time", and "quantum computing's one trick is to perform calculations on all superposition states at once" - plus, other quantum weirdness means the whole business "can then be done 'in the cloud' completely securely".

This week has seen two more advances in the field. In one, a team reporting in Nature describes the first fully quantum network, in which "qubits" - quantum bits, the information currency of quantum computers - were faithfully shuttled between two laboratories.

In another, a team writing in Science says they have "entangled" two qubits - representing the simplest core of a quantum computer - within a semiconductor, materials that standard computer makers are already familiar with manufacturing.

(It has been truly busy recently; the largest ensemble of working qubits was reported on Arxiv in January, and the biggest quantum computer number-crunching feat was published in Physical Review Letters in late March.)

Bet it works
It is all a bit bewildering, so to sum up the state of the field: very small-scale, laboratory-bound quantum computers that can solve simple problems exist; most researchers say the idea of massively scaled-up versions looks perfectly plausible on paper; but making them is an engineering challenge that practically defies quantifying.

Scott Aaronson, an expert in the theory of computation at the Massachusetts Institute of Technology, is one believer in the scaled-up quantum computer. He recently offered a $100,000 prize for a convincing proof that such a device could not be made.

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Essence of the quantum advantage

"Qubit" probability distributions
Scott Aaronson, MIT

You frequently hear that quantum computers "try all the possibilities in parallel" - that's a very drastic oversimplification.

We talk about a 30% chance of rain tomorrow - we'd never say there's a negative 30% chance. But quantum mechanics is based on "amplitudes", which can also be negative. If you want to find the probability that something will happen, you have to add up all the amplitudes.

With a quantum computation you're trying to choreograph things such that for a given wrong answer there are all these different paths that could lead to it, some with positive amplitude and others with negative amplitude - they cancel each other out.

For a given right answer, the paths leading to that should all be positive or all negative, and amplitudes reinforce. When you measure it, the right answer should be measured with high probability.

But he has no illusions that it is just around the corner.

"I get kind of annoyed by all the (popular media) articles reporting every little experimental advance," he told BBC News.

"The journalists have to sell everything, so they present each thing like we're really on the verge of a quantum computer - but it's just another step in what is a large and very difficult research effort.

"It was more than 100 years between Charles Babbage and the invention of the transistor, so I feel like if we can beat that, then we're doing well - but that's a hundred years for people to say 'works great on paper, but where is it?'"

More than that, though, even the most optimistic researchers believe that quantum computers will not be a wholesale replacement for computers as we now know them.

The only applications that everyone can agree that quantum computers will do markedly better are code-breaking and creating useful simulations of systems in nature in which quantum mechanics plays a part.

Martin Plenio, director of the Institute for Theoretical Physics at the University of Ulm, Germany, said that "it might never happen that it will be a device that sits here under my desk".

"A quantum computer can do all the things that a classical computer can do, and some of those things it can do much better, faster, like factoring large numbers," he told BBC News.

"But for many questions it's not going to be superior at all. There is simply no point to use a quantum computer to do your word processing."

Quantum add-ons
Others are more sanguine about the utility of what will come out of the current research efforts.

Alan Woodward, a professor of computing at the University of Surrey, cites a couple of recent advances that, to his mind, signify a significant push toward a computer that might sit under his or Prof Plenio's desk.

Quantum entanglement experiment
Quantum experiments are still complex and bulky lab-based beasts
Most quantum computers to date have been designed to tackle a single problem, unlike the general-purpose computers we use now. But Prof Woodward says that a report in Nature Photonics in December represents the first "programmable" quantum computer.

And, he said it is significant that an industry giant like IBM is getting into the game; at a meeting of the American Physical Society in March, IBM researchers reported significant advances in just how long they could preserve the quantum information in their qubits.

"Are you going to have a purely quantum computer in five years? No - what you'll have is elements of these things coming out, you always do with technology," he told BBC News.

"In the same way you have a graphics processor card along with a main processor board in a modern computer, you'll see things added on; people will find a means of using quantum computing and the quantum techniques, and that's how I think it'll move forward.

"And those I can definitely see in the five-year period."

Prof Woodward is in the minority in thinking that the consumer market will benefit widely from quantum computers; the problem of course is making predictions about a technology that has, since its inception, always seemed possible but even now is not incontrovertibly achievable.

Dr Aaronson concedes that perhaps the long term may bear out a greater desire and use for it.

"It's hard for me to envision why you'd want a quantum computer for checking your email or for playing Angry Birds. But to be fair, people in the 1950s said 'I don't see why anyone would want a computer in their home', so maybe this is just limited imagination.

"Maybe quantum video games will be all the rage 100 years from now."

40

Natural Science / Quantum memory 'world record' smashed

« on: August 05, 2014, 06:22:25 PM »

A fragile quantum memory state has been held stable at room temperature for a "world record" 39 minutes - overcoming a key barrier to ultrafast computers.

"Qubits" of information encoded in a silicon system persisted for almost 100 times longer than ever before.

Quantum systems are notoriously fickle to measure and manipulate, but if harnessed could transform computing.

The new benchmark was set by an international team led by Mike Thewalt of Simon Fraser University, Canada.

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"39 minutes may not seem very long. But these lifetimes are many times longer than previous experiments”

Stephanie Simmons
Oxford University
"This opens the possibility of truly long-term storage of quantum information at room temperature," said Prof Thewalt, whose achievement is detailed in the journal Science.

In conventional computers, "bits" of data are stored as a string of 1s and 0s.

But in a quantum system, "qubits" are stored in a so-called "superposition state" in which they can be both 1s and 0 at the same time - enabling them to perform multiple calculations simultaneously.

The trouble with qubits is their instability - typical devices "forget" their memories in less than a second.

There is no Guinness Book of quantum records. But unofficially, the previous best for a solid state system was 25 seconds at room temperature, or three minutes under cryogenic conditions.

In this new experiment, scientists encoded information into the nuclei of phosphorus atoms held in a sliver of purified silicon.

Magnetic field pulses were used to tilt the spin of the nuclei and create superposition states - the qubits of memory.

The team prepared the sample at -269C, close to absolute zero - the lowest temperature possible.

Artist's impression of a phosphorus atom qubit in silicon, showing a ticking clock
When they raised the system to room temperature (just above 25C) the superposition states survived for 39 minutes.

What's more, they found they could manipulate the qubits as the temperature of the system rose and fell back towards absolute zero.

At cryogenic temperatures, their quantum memory system remained coherent for three hours.

"Having such robust, as well as long-lived, qubits could prove very helpful for anyone trying to build a quantum computer," said co-author Stephanie Simmons of Oxford University's department of materials.

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Future directions in computing

Spintronics
Quantum
Photonics
DNA computing
Chemical computing
"39 minutes may not seem very long. But these lifetimes are many times longer than previous experiments.

"We've managed to identify a system that seems to have basically no noise."

However she cautions there are still many hurdles to overcome before large-scale quantum computations can be performed.

For one thing, their memory device was built with a highly purified form of silicon - free from the magnetic isotopes which interfere with the spin of nuclei.

For another, the spins of the 10 billion or so phosphorus ions used in this experiment were all placed in the same quantum state.

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"What's most important is this is silicon. The global investment in this material means it has a lot of potential for engineering”

Dr Thaddeus Ladd
HRL Laboratories
Whereas to run calculations, physicists will need to place different qubits in different states - and control how they couple and interact.

"To have them controllably talking to one another - that would address the last big remaining challenge," said Dr Simmons.

Independent experts in the quantum field said the new record was an "exciting breakthrough" that had long been predicted.

"This result represents an important step towards realising quantum devices," said David Awschalom, professor in Spintronics and Quantum Information, at the University of Chicago.

"However, a number of intriguing challenges still remain. For instance - will it be possible to precisely control the local electron-nuclear interaction to enable initialisation, storage, and readout of the nuclear spin states?"

The previous "world record" for a solid state quantum system at room temperature - 25 seconds - was held by Dr Thaddeus Ladd, formerly of Stanford University's Quantum Information Science unit, now working for HRL Laboratories.

"It's remarkable that these coherence states could be held for so long in a measurable system - as measurement normally introduces noise," he told BBC News.

"It's also a nice surprise that nothing goes wrong warming up and cooling the sample again - from an experimental point of view that's pretty remarkable.

"What is perhaps most important is that this is silicon. The global investment in this particular material means that it has a lot of potential for engineering."

41

Natural Science / 'Quantum Cheshire Cat' becomes reality

« on: August 05, 2014, 06:21:59 PM »

Scientists have for the first time separated a particle from one of its physical properties - creating a "quantum Cheshire Cat".

The phenomenon is named after the curious feline in Alice in Wonderland, who vanishes leaving only its grin.

Researchers took a beam of neutrons and separated them from their magnetic moment, like passengers and their baggage at airport security.

They describe their feat in Nature Communications.

The same separation trick could in principle be performed with any property of any quantum object, say researchers from Vienna University of Technology.

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Well! I've often seen a cat without a grin, but a grin without a cat! It's the most curious thing I ever saw in my life!”

Alice's Adventures in Wonderland
Their technique could have a useful application in metrology - helping to filter out disturbances during high-precision measurements of quantum systems.

Schrodinger's paradox
In Lewis Carroll's classic children's story, the Cheshire Cat gradually disappears, leaving only its mischievous grin.

This prompts Alice to exclaim: "Well! I've often seen a cat without a grin, but a grin without a cat! It's the most curious thing I ever saw in my life!"

In the world familiar to us, an object and its properties are always bound together. A rotating ball, for instance, cannot become separated from its spin.

Cheshire Cat
The cat (the neutron) goes via the upper beam path, while its grin (the magnetic moment) goes via the lower
But quantum theory predicts that a particle (such as a photon or neutron) can become physically separated from one of its properties - such as its polarisation or its magnetic moment (the strength of its coupling to an external magnetic field).

"We find the cat in one place, and its grin in another," as the researchers once put it.

The feline analogy is a nod to Schrodinger's Cat - the infamous thought experiment in which a cat in a box is both alive and dead simultaneously - illustrating a quantum phenomenon known as superposition.

To prove that the Cheshire Cat is not just a cute theory, the researchers used an experimental set-up known as an interferometer, at the Institute Laue-Langevin (ILL) in Grenoble, France.

A neutron beam was passed through a silicon crystal, sending it down two different paths - like passengers and their luggage at airport security.

By applying filters and a technique known as "post-selection", they were able to detect the physical separation of the neutrons from their magnetic moment - as measured by the direction of their spin.

"The system behaves as if the neutrons go through one beam path, while their magnetic moment travels along the other," the researchers reported.

ILL reactor
The high flux neutron source at the ILL made the weak signal of the 'Cheshire Cat' detectable
Glimpsing this Cheshire Cat requires what quantum physicists call "weak measurement," whereby you interact with a system so gently that you avoid collapsing it from a quantum state to a classical one.

Their delicate apparatus could have useful applications in high-precision metrology, the researchers say.

"For example, one could imagine a situation in which the magnetic moment of a particle overshadows another of the particle's properties which one wants to measure very precisely.

"The Cheshire Cat effect might lead to a technology which allows one to separate the unwanted magnetic moment to a region where it causes no disturbance to the high-precision measurement of the other property."

42

Natural Science / Hummingbirds' wings 'shape-shift'

« on: August 05, 2014, 06:21:32 PM »

Footage shot with high-speed cameras has revealed how hummingbird wings bend and flex, to keep the birds in the air.

Masateru Maeda, a PhD student at Chiba University in Japan, captured the footage.

The ultimate aim of his measurements of the movements of the wings is to copy their function in the design of flying robots.

The scientist presented his findings at the Society for Experimental Biology's annual meeting in Valencia, Spain.

The researchers captured their footage at Tama Zoological park in Tokyo.

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Flapping and flying

Moth in flight (c) SPL
As birds and insects move through the air, their wings are held at a slight angle, which deflects the air downward.

This deflection means the air flows faster over the wing than underneath, causing air pressure to build up beneath the wings, while the pressure above the wings is reduced. It is this difference in pressure that produces lift.

Flapping creates an additional forward and upward force known as thrust, which counteracts the insect's weight and the "drag" of air resistance.

The downstroke or the flap is also called the "power stroke", as it provides the majority of the thrust. During this, the wing is angled downwards even more steeply.

You can imagine this stroke as a very brief downward dive through the air - it momentarily uses the animal's own weight in order to move forwards. But because the wings continue to generate lift, the creature remains airborne.

In each upstroke, the wing is slightly folded inwards to reduce resistance.

Springwatch: Thermal cameras expose secrets of insect flight
Watch hummingbird wings in slow motion
The team chose hummingbirds as their "wing model" because they can be studied so easily; they hover quite still as they feed on nectar.

"And they're very small," added Mr Maeda. "Larger birds that cannot hover have to be studied in wind tunnels."

But to get his footage, Mr Maeda had to work in the glasshouse of the zoo, which is kept at 35C for the birds and butterflies that live there.

He trained his high-speed camera on a nectar feeder in order to capture shots of hummingbirds as they hovered.

"We are curious about the precise wing shape," Mr Maeda told BBC News. "The feathers [move and] change the wing area as they are flapping."

This movement of the primary flight feathers, the researchers found, changes the shape and size of the wing in such a way as to very precisely control the lift they generate.

Flapping robots
The eventual aim is to design wings for miniature flying robots that would be able to perform in a similar way.

Mr Maeda and his colleagues have already started a collaboration with engineers at Chiba University to design a flexible, bird-inspired wing.

The team also hopes to learn more about the hummingbirds' impressive hovering capabilities.

Mr Maeda said that the birds must have a very acute sense of their wings' shape in order to remain so still in the air.

"If the wing shape isn't optimised," he explained, "it will fail to produce lift and the bird will start to sink.

"So it must be able to sense this and correct the shape of its wings."

Tama Zoological Park glass house
Researcher Masateru Maeda had to spend hours capturing footage in the zoo's glass house

43

Natural Science / Hummingbirds edge out helicopters in hover contest

« on: August 05, 2014, 06:21:02 PM »

When it comes to flight, nature just has the edge on engineers.

This is according to a study comparing hummingbirds with one of the world's most advanced micro-helicopters.

Researchers found that - in terms of the power they require to lift their weight - the best hummingbird was over 20% more efficient than the helicopter.

The "average Joe" hummingbird, however, was on par with the helicopter, showing "how far flight engineering has come".

The findings are published in the Royal Society journal Interface.

Lead researcher Prof David Lentink, from Stanford University in California, explained that the flight performance of a hummingbird - the only bird capable of sustained hovering - was extremely difficult to measure.

"Imagine a 4g bird," he said. "The forces they generate are tiny.

Continue reading the main story
Flapping and flying

Moth in flight (c) SPL
As birds and insects move through the air, their wings are held at a slight angle, which deflects the air downward.

This deflection means the air flows faster over the wing than underneath, causing air pressure to build up beneath the wings, while the pressure above the wings is reduced. It is this difference in pressure that produces lift.

Flapping creates an additional forward and upward force known as thrust, which counteracts the insect's weight and the "drag" of air resistance.

The downstroke or the flap is also called the "power stroke", as it provides the majority of the thrust. During this, the wing is angled downwards even more steeply.

You can imagine this stroke as a very brief downward dive through the air - it momentarily uses the creature's own weight in order to move forwards. But because the wings continue to generate lift, the creature remains airborne.

In each upstroke, the wing is slightly folded inwards to reduce resistance.

Springwatch: Thermal cameras expose secrets of insect flight
Watch hummingbird wings in slow motion
"As a result the drag of a hummingbird wing has never been measured accurately."

Drag is the force opposing the upward force of lift that birds' wings generate by flapping.

Prof Lentink and his team wanted to understand if feathered hummingbird wings were more efficient - using less power to overcome drag - than the engineered blades of a helicopter of a similarly tiny scale.

He and his colleagues compared the birds' performance to an advanced micro-drone called the Black Hornet - a 16g helicopter used for surveillance by British troops in Afghanistan.

To make the laboratory measurements, they used wings from hummingbird specimens kept in museums.

By putting these detached wings into an apparatus called a wing spinner, the team was able to measure exactly how much flapping power was required to lift the bird's weight.

Prof Lentink's colleagues at the University of British Columbia in Canada also made recordings of wild hummingbirds in flight, to measure the exact movement of their wings - which beat up to 80 times per second.

"By combining the wings' motion with the drag [that we measured in the lab], we were able to calculate the aerodynamic power hummingbird muscles need to provide to sustain hover," explained Prof Lentink.

One species - the Anna's hummingbird - was champion hoverer, performing much more efficiently than the helicopter.

But on average, the birds hovering performance was "on par with the helicopter".

"This shows that if we design the wings well, we can build drones that hover as efficiently, if not more efficiently, as hummingbirds," said Prof Lentink.

"Clearly we are not even close to hummingbirds in many other design metrics, such as wind gust tolerance, visual flight control through clutter, to name a few.

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Dr Mirko Kovac from Imperial College explains how drones whose design is inspired by nature are set to become part of our everyday lives
"But if we focus on aerodynamic efficiency, we are closer than we perhaps ever imagined possible."

Dr Mirko Kovac from the aerial robotics lab at Imperial College London said the study was a great example of research at the interface of biology and engineering.

"Studying hummingbird wing shapes can not only give insights into the biomechanics of animals," he told BBC News, "but the gained insights can also be used to build the next generation of flying micro robots."

44

Natural Science / Scientists use stem cells to regenerate human corneas

« on: August 05, 2014, 06:20:29 PM »

Scientists have developed a new technique to regrow human corneas.

Using key tracer molecules, researchers have been able to hunt down elusive cells in the eye capable of regeneration and repair.

They transplanted these regenerative stem cells into mice - creating fully functioning corneas.

Writing in the journal Nature, they say this method may one day help restore the sight of victims of burns and chemical injuries.

Limbal stem cells (LSC) are crucial for healthy eyesight - these cells work to maintain, repair and completely renew our corneas every few weeks.

Without them the cornea - the transparent outermost layer of the eye - would become cloudy and our vision disrupted.

A deficiency of these cells due to disease or damage through injury to the eye are among the commonest reasons behind blindness worldwide.

But the cells have so far been extremely difficult to identify, buried in a matrix of other structures in the limbal part of the eye - the junction between the cornea and the white of the eye (the sclera).

'Fluorescent flags'
Now scientists from the Massachusetts Eye and Ear Infirmary, Boston Children's Hospital, Brigham and Women's Hospital and the VA Boston Healthcare System have identified a key tracer molecule - known as ABCB5 - naturally present on the surface of limbal stem cells.

Though ABCB5 has been known about for some time in other parts of the body, this is the first time it has been spotted on LSCs, helping to single out these elusive cells.

Researchers have been able to tag these cells with fluorescent molecular flags.

In their study, the scientists used this tagging technique to instantly identify a pool of LSCs on donated human corneas.

After being transplanted to mice, these cells were able to generate fully functioning human corneas.

Prof Markus Frank, of Boston Children's Hospital, a lead author in the research, told the BBC: " The main significance for human disease is we have established a molecularly defined population of cells that we can extract from donor tissue.

"And these cells have the remarkable ability to self-regenerate. We hope to drive this research forward so this can be used as a therapy."

Harminder Dua, professor of ophthalmology at the University of Nottingham, who was not involved in this study, said: "This paper represents a very comprehensive and well conducted piece of work that takes use closer to the precise identification of stem cells.

"Applying this knowledge to a clinical setting could help improve the outcomes for patients who need corneal reconstruction."

45

Natural Science / Display screen technology could correct vision problems

« on: August 05, 2014, 06:20:03 PM »

Engineers have developed a prototype tablet display that compensates for an individuals' vision problems.

The system uses software to alter the light from each individual pixel on the screen, based on the person's glasses prescription.

The researchers also added a thin plastic pin hole filter to enhance the sharpness of the image.

The team say the technology could help millions who need corrective lenses to use their digital devices.

Around one person in three in the UK suffers from short-sightedness or myopia. In the US, around 40% while in Asia it is more than half the population.

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Instead of relying on optics to correct your vision, we use computation”

Fu-Chung Huang,
University of California
In recent years there have been a number of projects that have attempted to use computing screens to correct vision problems.

The authors of this latest study say their prototype offers "significantly higher contrast and resolution compared to previous solutions".

Follow the light
The team from the University of California, Berkeley, working with colleagues at Massachusetts Institute of Technology (MIT), developed an algorithm that adjusts the intensity of each direction of light that emanates from a single pixel in an image, based on the user's specific visual impairment.

Their prototype used an iPod, with a printed pinhole mask attached to the screen. To check the images, the researchers used a digital single-lens reflex (DSLR) camera which was set up to simulate a person who was farsighted.

blur
On the right is a computer simulation of the best picture quality possible using the new prototype display
The altered images from the iPod appeared sharp and clear to the camera, showing that the prototype was effective in correcting this sight issue.

"The significance of this project is that, instead of relying on optics to correct your vision, we use computation," said lead author Fu-Chung Huang. "This is a very different class of correction, and it is non-intrusive."

The research team believe that their idea, when refined further, could be of benefit to people who suffer from more difficult-to-treat vision issues.

"We now live in a world where displays are ubiquitous, and being able to interact with displays is taken for granted," said Prof Brian Barsky, from UC Berkeley, the project leader.

"People with higher order aberrations often have irregularities in the shape of the cornea, and this irregular shape makes it very difficult to have a contact lens that will fit.

"In some cases, this can be a barrier to holding certain jobs because many workers need to look at a screen as part of their work. This research could transform their lives."

Battery question
It should be stressed that while the research is at a very early stage, the engineers behind it the approach believe it has great potential, in the field of visual correction and beyond.

They envisage displays that users with different visual problems can view at the same time and see a sharp image.

"In the long run we believe that flexible display architectures will allow for multiple different modes, such as glass free 3D image display, vision corrected 2D image display and combinations of vision corrected and 3D image displays," the authors write.

No consideration has been given, at this stage, to the impact such a system might have on the battery life of digital devices. This could also be an important factor going forward.

The research will be presented at an international conference on computer graphics called SIGGRAPH, in Vancouver in August.bbc