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Diamonds are celebrated for their enduring beauty and hardness but they can also be a physicist’s best friend.

In Nature Photonics and Science an international team of scientists report that a strange quantum state called ‘entanglement’ has been achieved in two 3mm-wide diamond crystals, spaced 15cm apart, at room temperature.

‘One of the weird effects well known from atomic-scale systems is the possibility of superposition - the ability of an object to be in two places at once,’ explains Ian Walmsley of Oxford University’s Department of Physics, a member of the team behind the research.

‘We show that you can take two diamonds - not quite everyday objects, but at least simple and recognizable - and put them in such a state: in particular a superposition of a state of one diamond vibrating and the other not, and vice versa.

‘This special type of superposition is called "entangled" and is of a kind that may be used for applications of quantum physics to new technologies, especially in communications and computing.’

Because it is so easily disturbed by its surroundings entanglement can only normally be observed in isolated systems cooled to temperatures close to absolute zero.

But the structure of diamond makes it different: ‘Exciting a vibrational motion in diamond requires a temperature of about 2000 degrees Celsius,’ comments Joshua Nunn of Oxford University’s Department of Physics, also a member of the research team.

‘So at room temperature the vibrations are non-existent. The system behaves in that sense like a very cold cloud of atoms.’

The researchers, from Oxford University, National University of Singapore, and National Research Council of Canada, also sought to exploit another property of diamond: it tends to scatter light in such a way that a photon striking it can be converted to a lower energy photon, with the remaining energy being converted into a vibration.

This vibration or ‘ringing’ in the diamond crystal can be detected using a laser.

‘We sent bursts of laser light through both diamonds,’ Ian tells me. ‘Most of the time the light would travel straight through the crystals but sometimes the light would dump some energy in one of the crystals, setting it ringing, and the light would then emerge with less energy - a lower frequency.’

The light is combined after the crystals so that when a low frequency pulse is detected, it is possible for scientists to know that one diamond is vibrating, but not which one.

‘In fact, the universe doesn't know which diamond is vibrating!’ Joshua explains. ‘The diamonds are entangled, with one vibration shared between them, even though they are separated in space. We could use a similar technique to measure the diamonds and determine that this was the case.’

The fact that entanglement is occurring inside everyday objects is not a surprise, but up until now most people would have thought that it would be impossible to observe: being ‘washed out’ or otherwise disturbed by noise from the environment.

Joshua suggests that their approach might encourage scientists to look for strange quantum effects in places where previously they wouldn’t have expected to be able to spot them.

Whilst any practical applications for the work are a long way off, the Nature Photonics paper does describe how it might be possible to build a diamond ‘quantum memory’ for photonic quantum computing.

Ian comments: ‘Several groups around the world have built different elements of a nanophotonic processor, and a vibrational quantum memory for photons could be incorporated into these.’

Another possibility is explored in a related piece of work using these diamonds that makes use of the quantum character of "nothingness". It exploits this possibility to generate truly random numbers: something that could help to improve the security of electronic communications and transactions.

Today scientists at the Large Hadron Collider announced tantalising news about the biggest piece missing from the physics jigsaw.

The Higgs boson is a hypothetical particle used to explain why many of the fundamental particles in the Standard Model of particle physics have mass.

Proving if it exists is tricky because the model doesn't predict its exact mass.

Now results from the Large Hadron Collider (LHC) suggest that, if it exists, the Higgs is most likely to have a mass between 116-130 gigaelectronvolts (GeV), according to the ATLAS experiment, and 115-127 GeV according to CMS.

Both experiments saw a ‘spike’ in their data around 124-125 GeV - this might be a random fluctuation or, as BBC News Online reports, it could just be a first glimpse of the Higgs.

Reacting to these early results Alan Barr of Oxford University’s Department of Physics, ATLAS UK physics coordinator, commented:

‘It is a testament to the superb performance of the LHC that we are already finding hints that might be indicative of Higgs bosons so early in the machine’s lifetime.

'The results are not yet conclusive, but during the next year we will know whether the Higgs boson exists in the form predicted by the “Standard Model” of particle physics. The analysis has to be done very carefully, since in scientific research the most interesting results are often found in unexpected places.

'We must bear in mind that the Standard Model is known to be incomplete, since it describes only that 5% of the universe that is made of atoms. What the LHC will tell us about the other 95% of the universe is likely to be an open question for many years to come.'

Chris Hays of Oxford University’s Department of Physics, another member of the ATLAS team, told me:

‘We have seen the first tantalizing hints of the Higgs boson after many years of pursuit. The concurrent signals in several different decay channels are suggestive.

‘Nonetheless the signals are still weak and more data are needed to determine if we are truly seeing the Higgs boson.’

UPDATE: Tony Weidberg, of Oxford University’s Department of Physics, also from the ATLAS team, comments:

'Science is a never ending frontier because as soon as one question is answered, more questions open up. If the hints of a standard model Higgs particle are confirmed next year, then the internal problems with the theory require the existence of new physics in the LHC energy regime.

'So this discovery would be the start of a new adventure. However, if we can exclude the existence of a Standard Model Higgs boson, then it raises the exciting question of just how particles like electrons do acquire mass. Again the LHC would be ideally placed to probe these questions.' 

Today saw the ESO give the go-ahead for work to begin on a series of roads on a mountain in Northern Chile.

But these aren’t just any roads; they will give access to Cerro Armazones, the site that has been chosen for the European Extremely Large Telescope (E-ELT).

E-ELT is planned to be the largest optical and infrared telescope in the world: it will be tens of times more sensitive than any current ground-based optical telescope.

Oxford University scientists are taking a lead role in the instrumentation for this £922m (€1082m) project, so today’s announcement from the ESO, which included funding for the roads and the adaptive optics mirror, is welcome news – even if a final decision to build the telescope won’t be made until mid-2012.

Niranjan Thatte of Oxford University’s Department of Physics led a European consortium that designed the E-ELT's HARMONI spectrograph, one of the proposed telescope's key instruments, he told me back in October:

‘HARMONI is an integral field spectrograph, simultaneously providing images and spectra of astrophysical objects in unprecedented detail, giving a fivefold improvement in spatial resolution over present-day telescopes.

'Combined with the immense light-gathering power of the E-ELT, it will enable ultra-sensitive observations of distant and nearby galaxies, super-massive black holes, young star-forming regions, extra-solar planets and other exotic objects.’

Yesterday, prior to the announcement, Isobel Hook of Oxford University’s Department of Physics, who chairs the E-ELT science working group, told the Today programme's Tom Feilden:

'The main improvement with this telescope over anything that's gone before is its size. The huge area allows you to collect light from much fainter more distant objects, while the diameter is what gives you the superb resolution - the sharpness of the images.'

With events at the LHC likely to dominate the headlines next week and next year, it’s worth considering just how much of an advance astronomy’s biggest science project could be:

The improvement in terms of resolution has been likened to the leap from the naked eye to the first telescopes used by Galileo and Harriot in the 1600s.

You can read more about HARMONI in our news story, whilst for more about E-ELT, and to listen to an interview with Niranjan, check out Tom Feilden's Blog.

It’s still a long road ahead for the E-ELT but, if approved, construction could start next year, with the telescope being operational early in the next decade.

Our galaxy is a relatively quiet neighbourhood with the supermassive black hole at its heart gently dozing: or is it?

The recent discovery of huge gamma-ray emitting ‘bubbles’ around the Milky Way is challenging this assumption and posing a new puzzle: just where do these bubbles come from?

Philipp Mertsch and Subir Sarkar of Oxford University’s Department of Physics recently reported in Physical Review Letters a model that could explain the origins of these strange phenomena. I asked them about bubbles, ‘feeding’ black holes, and how their ideas could be tested…

OxSciBlog: What are 'Fermi bubbles' and where are they found?
Philipp Mertsch: The 'Fermi bubbles' are gigantic structures above and below the centre of our Galaxy which were discovered by astrophysicists at Harvard in a gamma-ray sky map made by NASA's Fermi satellite.

The bubbles extend ~50,000 light years above and below the galactic plane, i.e. they are about the same size as the disk of the Galaxy. A correlated structure can also be seen in the X-ray map made by the ROSAT satellite.

It may seem surprising that such huge structures have gone unnoticed earlier - this is a testimony to how advances in astronomical instrumentation lead to serendipitous discoveries!

OSB: Why is it important to understand them?
Subir Sarkar: The bubbles are important for a variety of reasons. First, their origin is very likely related to an energetic outflow from the the supermassive black hole lurking at our Galactic Centre - it is supposedly not "feeding" but clearly was doing so as recently as a million years ago. Understanding the mechanism of their gamma-ray emission also holds clues as to what is powering them.

Moreover this region of the sky is a prime target for dark matter annihilation signals - while the bubbles are themselves very unlikely to be due to dark matter annihilations, we need to understand them in meticulous detail if we want to look for the much smaller signal in gamma-rays expected from dark matter.

OSB: How have scientists previously tried to explain them?
PM: So far, scientists have considered the same processes that are believed to produce gamma-rays in astrophysical sources, for example decays of neutral pions created by interactions of high energy protons with ambient matter, and inverse-Compton scattering of background photons by high energy electrons.

High-energy protons are certainly present in the disk of the Milky Way, but it is not easy to explain how they could be transported to such large distances from the disk and be contained inside the bubbles for billions of years.

The problem with electrons is that they lose energy rapidly and would need to be reaccelerated - it has been suggested that this happens at hundreds of shock fronts inside the bubbles. However, there is no evidence for such an onion-like structure, in fact, the bubbles have a smooth surface and a well-defined, sharp edge.

OSB: What do you suggest may have produced the bubbles?
SS: The X-ray data from the ROSAT satellite suggest only one shock front which delineates the outer edge of the bubbles. This shock produces turbulence in the plasma behind it which can accelerate electrons to very high energies through a stochastic process first discussed by Enrico Fermi.

These electrons then transfer their energy to low energy photons from the microwave and infrared backgrounds as well as starlight, producing the gamma-rays observed.

It turns out that the variations of the plasma properties inside the bubbles can exactly reproduce the observations, namely the smooth surface and the sharp edges of the bubbles. The other models cannot explain this.

OSB: If you are correct what does this tell us about our galaxy/galaxy formation in general?
PM: An important question is of course where does this shock front come from? Looking at other galaxies we see similar bubbles being produced by jets powered from the central black hole. This is certainly a possibility for our own Galaxy.

In fact it is rather peculiar that the black hole at the centre of the Milky Way is so quiet - it now appears that this may just be a transient phase.

This picture is further supported by numerical simulations which have shown that a jet shooting out from the centre above and below the galactic plane can easily produce structures of the size and shape of the Fermi bubbles.

OSB: How could your ideas be tested?
SS: Our model for the gamma-ray emission predicts a unique energy-dependence: at lower energies, the surface of the bubbles is very smooth but at higher energies, the bubble inside should become fainter while only the edges stay bright. The energies at which this happens are beyond the reach of the Fermi satellite but with data from the forthcoming Cherenkov Telescope Array this shell-like structure should become observable. 

Whether you are playing poker or haggling over a deal you might think that you can hide your true emotions.

But telltale signs can reveal that you are concealing something, and now researchers at Oxford University and Oulu University are developing software that can recognise these ‘micro-expressions’ - which could be bad news for liars.

‘Micro-expressions are very rapid facial expressions, lasting between a twenty-fifth and a third of a second, that reveal emotions people try to hide,’ Tomas Pfister of Oxford University’s Department of Engineering Science tells me.

‘They can be used for lie detection and are actively used by trained officials at US airports to detect suspicious behaviour.

‘For example, a terrorist trying to conceal a plan to commit suicide would very likely show a very short expression of intense anguish. Similarly, a business negotiator who has been proposed a suitable price for a big deal would likely show a happy micro-expression.’

Tomas is leading efforts to create software that can automatically detect these micro-expressions - something he says is particularly attractive because humans are not very good at accurately spotting them.

He explains that two characteristics of micro-expressions make them particularly challenging for a computer to recognise:

Firstly, they are involuntary: ‘How can we get human training data for our algorithm when the expressions are involuntary?’ he comments. ‘We cannot rely on actors as they cannot act out involuntary expressions.’

The second big problem is that they occur for only a fraction of a second: this means that, with normal speed cameras, they will only appear in a very limited number of frames, leaving only a small amount of data for a computer to go on.

The researchers looked to tackle the first problem by an experiment in which those taking part were induced to suppress their emotions.

‘Subjects were recorded watching 16 emotion-eliciting film clips while asked to attempt to suppress their facial expressions,’ Tomas explains.

‘They were told that experimenters are watching their face and that if their facial expression leaks and the experimenter guesses the clip they are  watching correctly, they will be asked to fill in a dull 500-question survey. This induced 77 micro-expressions in 6 (now 21) subjects.’

To overcome the problem of the limited number of frames the researchers used a temporal interpolation method where each micro-expression is interpolated - essentially ‘gaps’ in the data are filled in with existing data - across a larger number of frames. This makes it possible to detect micro-expressions even with a standard camera.

Early results from the work are promising, with the automated method able to detect micro-expressions better than a human, Tomas comments:

‘The human detection accuracies reported in literature are significantly lower than our 79% accuracy. We are currently running human micro-expression recognition experiments on our data to get a directly comparable human accuracy.’

But the writing may not be on the wall for liars and con-artists just yet.

Automated recognition of micro-expressions is one thing, Tomas says, but detecting deception, and uncovering the truth, is considerably harder:

Micro-expressions should be treated only as clues that a person is hiding something, not as conclusive evidence for deception. They cannot indicate what that person is hiding or why they are attempting to conceal it.

Tomas adds: ‘That said, our initial experiments do indicate that our approach can distinguish deceptive from truthful micro-expressions, but we will need to conduct further experiments to confirm this.’