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Home » Page 1666

Light exhibits spin Hall effect

Shine a beam of light into a block of glass and you would expect it to change direction because, being denser, glass has a larger refractive index than air. You might not, however, expect the beam to split in two. Although only slight, this “spin Hall effect of light” has now been measured by physicists in the US, and the team claim their technique could open up avenues for detecting any particle or field with high accuracy.

Discovered nearly 130 years ago by Edwin Hall, the Hall effect describes how a transverse magnetic field can deflect a current of electrons as they pass through a metal sheet. More recently, physicists at the University of California at Santa Barbara in the US showed that a related phenomenon arises without a magnetic field for an electron current in a thin semiconductor. Known as the spin Hall effect, electrons with their spin pointing up veer to one side while electrons with their spin pointing down veer to the other.

Now, it looks like Hall phenomena can exist for particles other than electrons, with Onur Hosten and Paul Kwiat from the University of Illinois at Urbana-Champaign for the first time measuring the spin Hall effect for light. In their experiment, the spin-up and spin-down electrons are replaced by light with left and right circular polarizations. Meanwhile, the role of the electric field that drives the electron current through the semiconductor is performed by the transition from a low to high refractive index as the light passes from air into glass.

Maximizing separation

We believe we can achieve a resolution of picometres

The spin Hall effect for light should exist any time a beam of linearly polarized light, which comprises equal components of left and right circular polarization, enters a medium with a different refractive index. The left and right circularly polarized components will instantly shift away from each other and then continue to travel in parallel (see animation: splitting light). However, the separation is so small — on the order of nanometres — that the two beams will invariably still overlap each other.

The separation is small because the glass interface is essentially carrying out a “quantum weak measurement” of the polarization of each of the incoming photons. This type of measurement is often used in quantum information experiments to glean tiny amounts of knowledge about a system without disturbing it, but Hosten and Kwiat have instead tried to maximize its disturbance by forcing the light beam through polarizers before and after the interface.

Using this method they amplified the separation 10,000 times over, which enabled them to detect the two components on a position-sensitive photodiode a micron apart (Science Express doi: 10.1126/science.1152697).

Interfering waves

Why does the separation occur at all? The light beam is composed of many plane waves. When the beam changes direction at the air-glass interface, the polarizations of the individual plane waves are rotated by various amounts. However, because this polarization rotation is equivalent to a phase shift, the resultant waves interfere with each other to create two separated beams.

The Illinois team are now planning to improve on their technique. “We believe…we can achieve a resolution of picometres,” Hosten told physicsworld.com. But they are also keen to see it used on other systems. “The technique is not limited to position measurements, it is universal,” Hosten added.

UK opts for nuclear power

The UK government has today announced plans to replace the country’s existing nuclear power stations to help meet its target of reducing carbon emissions by 60% by 2050. The secretary of state for business John Hutton, who delivered the government’s plans in a white paper on nuclear power, said it would be inviting private energy firms to bring proposals to the table for building and maintaining new reactors. However, no planning permission for new nuclear stations has yet been given.

It will be very tight to replace existing nuclear stations on time Paul Howarth, Dalton Nuclear Institute

Nuclear power plants currently generate about a fifth of the UK’s electricity. However, all current nuclear reactors in the UK are expected to close by 2023 apart from Sizewell B in Suffolk, which is set to shut by 2035. With the government also keen to reduce carbon emissions, it now sees building new nuclear-power station as the solution to the country’s energy needs. “Every new nuclear power station will save the same amount of carbon emissions that are generated from around one million households,” Hutton told MPs in the House of Commons.

Government U-turn

The go-ahead for new stations is something of a U-turn for the UK government, which said in a previous energy white paper in 2003 that nuclear power was not the answer to growing energy demands. Although a government review of energy in 2006 came out in favour of nuclear power, Gregg Butler, a science-policy expert at the University of Manchester, thinks that the rejection of nuclear in the 2003 white paper has lost the UK valuable time. “I welcome the government’s recognition that nuclear energy is part of a mix with other forms of low-carbon electricity generation like wind and hydropower,” he says.

However, as the member states of the Nuclear Energy Agency warned in a report last November, there is a current worldwide shortage of trained workers who could build and design potential new reactors. The government will therefore have a job on its hands recruiting enough science and engineering graduates into the nuclear sector. Paul Howarth, director of research at the Dalton Nuclear Institute in Manchester, hopes that the government’s decision will mean that “nuclear science can now be seen as an attractive prospect for future science graduates”.

But as it could take around 10 years for new nuclear plants to be commissioned and built, Howarth says that “it will be very tight to replace existing nuclear stations on time”. He points out if the government had come out in favour of nuclear power at the time of the last white paper in 2003, then “we would already be at the stage where licences have been approved for new reactors”.

Casimir effect goes classical

Physicists in Germany have made the first direct measurements of the “critical Casimir effect”, a classical analogue of the strange quantum effect that draws two conducting surfaces together in a vacuum. They also say that the classical effect can be easily tuned to repel rather than attract for reducing undesirable friction in nanomachines.

The quantum Casimir effect comes about because a vacuum always contains fluctuating electromagnetic fields. Normally these fluctuations are roughly the same everywhere, but two close conducting surfaces set “boundary conditions” that limit the number of allowed field frequencies between them. Only waves that can fit multiples of half a wavelength between the surfaces resonate, leaving non-resonating frequencies suppressed. The result is that the total field inside a gap between conductors cannot produce enough pressure to match that from outside, so the surfaces are pushed together.

The critical Casimir effect has the same underlying principle, but is a classical phenomenon that arises in a mixed liquid close to its critical point — the point, defined by a threshold temperature and pressure, beyond which the gas and liquid phases are indistinguishable. A mixed liquid taken towards its critical point gradually begins to separate into regions of its constituent substances, the size and shape of which fluctuate like the quantum fields in a vacuum. And, like the quantum Casimir effect, two close surfaces in such a liquid set boundary conditions, this time by preferring to be in contact with one of the substances over the other. To fulfil these conditions, the surfaces attempt to surround a single region of the preferred substance by drawing together.

‘Softest spring’

In our experiment there is probably the softest spring imaginable Clemens Bechinger, University of Stuttgart

Predicted in 1978 by Michael Fisher and the late Pierre-Gilles de Gennes, the critical Casimir effect has until now only been glimpsed indirectly because no one has perfected a technique that is sensitive enough. Atomic force microscopy has been one possibility, but the cantilevers are too hard. Clemens Bechinger and colleagues from the University of Stuttgart have got around the problem with a technique called total internal reflection microscopy, which can detect forces down to one femtonewton (10–15 N). “In our experiment there is no cantilever at all, which is probably the softest spring imaginable,” says Bechinger.

Using this technique, the Stuttgart team can measure the attraction of a 3 µm-diameter polystyrene ball to the inside surface of a glass filled with water and the oil 2,6-lutidine, a mixture that has its critical point at a convenient 34 °C. They begin by shining a laser at a sharp angle onto the outside of the glass, which reflects leaving only fast-decaying “evanescent” light leaking through to the inside. Next, they measure the amount that the ball scatters this evanescent light back to a photon counter to tell how the distance between it and the glass changes.

Because the ball is constantly bombarded by molecules in the liquid, the researchers have to use statistical analysis to distinguish the sudden movements towards the glass that result from the critical Casimir effect. From these displacements they calculated the effect of the force as about 600 fN (Nature 451 172).

Reverse effect

I am not sure if people want to have such mixtures inside their NEMS Astrid Lambrecht, Kastler Brossel Laboratory

The ball attracts to the glass surface because Bechinger and colleagues coated both of them to both prefer contact with either oil or water. However, they also found that they could turn the attraction into repulsion by giving the surfaces opposite preferences. In this scenario, the surfaces need to move apart to accommodate two different regions. Bechinger says this reverse critical Casimir effect could be useful in nanoelectromechanical systems (NEMS) for reducing the friction caused by the quantum Casimir effect.

“The effect is very interesting and its observation is certainly important,” Astrid Lambrecht, a physicist from the Kastler Brossel Laboratory in Paris, France told physicsworld.com. “It can potentially have applications in nanotechnology, but far as applications in NEMS are concerned I am not sure if people want to have such mixtures inside their NEMS, especially as the mixture properties depend on the temperature.”

Japanese particle physics in good health

The particle physics community started 2008 with a bad case of the January blues, thanks to major budget cuts announced by the US and UK just before Christmas. But some comfort may be taken from very positive plans for the future unveiled by the Japanese high-energy physics laboratory, KEK.

The 20-page roadmap report outlines an ambitious five-year plan that includes a major upgrade to KEK’s flagship “B-factory” and a strong commitment to the proposed International Linear Collider (ILC) — two areas that have suffered greatly as a result of the recent cuts in the UK and US.

“Given the UK’s decision to pull out of the ILC and the funding debacle in the US, this report demonstrates the sustained commitment to high-energy physics of the Japanese — who, of course, are one of the leading contenders to host the ILC,” says Brian Foster of Oxford University and European director of the ILC global design effort.

Our roadmap describes the importance of promoting short- and long-term projects in particle physics in parallel and internationally Atsuto Suzuki, KEK director general

KEK, located just north of Tokyo, is one of the world’s leading high-energy physics labs. Its main facility is a 3 km-circumference electron-positron collider called KEK-B that produces copious quantities of B-mesons to be studied by the Belle detector. The facility has led to major progress in our understanding of CP violation, as well as revealing several exotic new particles. Belle’s US counterpart, the PEP-II/BaBar B-factory at the Stanford Linear Accelerator Center, may be forced to shut down this March as a result of the funding situation.

The laboratory has also reinforced Japan’s already dominant position in neutrino physics, with the K2K experiment firing a beam of muon neutrinos at the SuperKamiokande experiment 250 km away to study neutrino oscillations.

Five main proposals

According to KEK director general Atsuto Suzuki, who began his three-year term in April 2006, the main purpose of the roadmap is to maintain KEK’s role as a leading accelerator-science institution. The report contains five main proposals:

  • operate the Japan Proton Accelerator Research Complex (JPARC), a multi-purpose proton accelerator located near the main KEK site, which, once completed, will provide an improved neutrino-beam experiment called T2K;
  • upgrade KEK-B to produce a much higher collision rate, and improve the Belle detector accordingly (this latter task alone is expected to involve an international collaboration of some 600 physicists);
  • continue operating and improve the “photon factory”, KEK’s synchrotron light source;
  • promote KEK’s commitment to the Large Hadron Colllider, which is due to start up at CERN this year;
  • develop advanced accelerator and detector technologies to help establish the next generation synchrotron radiation facility, to promote material and life science research via a THz light source, and to promote technical developments for the ILC — in particular the superconducting accelerator system.
Belle at KEK
Belle at KEK

“Our roadmap describes the importance of promoting short- and long-term projects in particle physics in parallel and internationally,” Suzuki told physicsworld.com. “Government has already approved the advanced accelerator technology R&D, including the ILC development for the next fiscal year, so we hope the budget cutbacks in the UK and US are temporary.”

Like many in the high-energy physics community, Dave Wark of Imperial College, London would be overjoyed to see the proposals put into practice. “The commitment and ambition of our Japanese colleagues is refreshing and reassuring,” he says. “KEK has shown itself to have great skill in attacking the big questions in particle physics, so let’s hope that the Japanese government responds positively to the programme laid out in the roadmap.”

‘Colour’ X-ray images reveal more

Researchers in the UK have built a prototype X-ray scanner that uses radiation at multiple wavelengths to create detailed 3D images in “colour”. The team claims that the new scanning technique could be used in a range of applications including medicine, security scanners and aerospace engineering.

Modern computed tomography (CT) scanners create high-resolution 3D images of the human body and other solid objects using a beam of X-rays with one specific wavelength. However, the technique could be improved upon by using a polychromatic beam of X-rays with a range of different wavelengths, which would allow the identification of different tissue types.

Now, researchers at the University of Manchester in the UK have developed a scanner that uses all of the wavelengths within a polychromatic X-ray beam to do just that (J. R. Soc. Interface doi: 10.1098/rsif.2007.1249).

Technology challenge

Building such a system called for the development of two key components: an array of collimating tubes to guide X-rays scattered from the sample and a pixellated, energy-sensitive detector to detect the collimated beam of scattered X-rays. Working with researchers at the University of Cambridge, UK, Robert Cernik and colleagues at Manchester used laser drilling to create the collimators. A spectroscopic-grade detector was fabricated in collaboration with the UK’s Rutherford Appleton Laboratory and Daresbury Laboratory.

The prototype device comprises a 16 × 16 array of 50 µm-diameter collimators, plus a corresponding 16 × 16 array of 300 µm2 wavelength-sensitive silicon pixel elements. To create a colour X-ray image, a polychromatic beam is incident upon the sample and the X-rays are scattered into the collimator array, which filters and directs the beams onto the detector.

As each pixel only samples a small volume, defined by the intersection of the incident and diffracted beams, the resulting images offer a high spatial resolution. The use of an array-based detector reduces the time taken to record each image to just a few minutes, lowering the radiation dose to the sample, or ultimately the patient.

The total scattering count at each pixel is used to create a 3D image of the sample. “Three-dimensional imaging is achieved by moving the sample through the fan-shaped beam in one simple z motion,” Cernik explained. “The detector and collimator assembly give you the spatial resolution in the x (the depth of the sample) and y directions.”

Meanwhile, each pixel also records the X-ray diffraction pattern as a function of wavelength from each intersection volume in the sample. This information can then be used to identify the material present at that particular point. In addition, the scattered spectra contain X-ray fluorescence information that can also be used to characterize the material.

The team tested the system on a variety of samples, starting with a thin polymer sheet marked with a test cross. When imaged using a 5 × 5 mm X-ray beam, the cross was clearly visible. The researchers also imaged a section of deer-antler bone. The system was able to image strut-like tissue structures in the bone called trabeculae and provide some information about their composition.

Cernik anticipates that one of the main medical applications of the technique will be to distinguish normal from abnormal tissues.

BEC goes with the flow

Superfluidity, where a liquid flows without friction, and superconductivity, where an electric current flows without resistance, have become familiar low-temperature phases of condensed matter. Now physicists in the US have observed similar “persistent flow” in a Bose–Einstein condensate (BEC), which might help to explain how the BEC phase is related to superconductors and superfluids.

A BEC occurs when a gas of bosons, or atoms of integer spin number, is cooled to such low temperatures that the vast majority of them fall into the same zero-momentum state. This means that the atoms behave as a single coherent entity, a property shared by superfluids and superconductors. However, these phases are not pure BECs because they both have strong atomic interactions, which drag many of the atoms into higher momentum states. By contrast a BEC only has weak interactions between atoms.

Scientists have shown before that, despite the differences, BECs and superfluids can both behave similarly by supporting quantized vortices of atoms. But until now they have not been able to make a BEC exhibit one of the most recognizable trademarks of superfluids and superconductors — persistent flow.

Transferring momentum

Bill Phillips, Kris Helmerson and colleagues at the National Institute of Standards and Technology (NIST) in Maryland can instigate persistent flow in a BEC consisting of a gas of sodium atoms cooled to just above absolute zero.

They begin by trapping the BEC into a circular shape with magnetic fields, and then puncture the middle with a laser to create a repulsive potential — essentially making the trap toroidal, or ring-shaped. They then shine two laser beams into the BEC from opposite directions. Atoms absorb a photon from one of these beams and then re-emit it into the other, leaving themselves with the difference in angular momentum of the beams.

The result of this momentum transition is that all of the atoms in the ring are set in persistent flow (Phys. Rev. Lett. 99 260401). The NIST team have made it continue for up to 10 seconds, but Helmerson told physicsworld.com that it is only technical limitations preventing them from making it perpetual. “If there was no drift in the experimental conditions and the vacuum [surrounding the BEC] was much better, then the flow should continue indefinitely,” he said.

The researchers suggest that a quantum tunnel barrier could be inserted into the ring to make it analogous to a “superconducting quantum interference device” (SQUID), possibly shedding light on the similarities between BECs and superconductors. In addition, they think they could modify their ring to tightly confine the gas, which might help physicists to understand how BECs are related to superfluids in one or two dimensions.

Research funding should reward unpredictability

Particle-physics experiments can cost hundreds of millions or even billions of dollars — and with that kind of money at stake, debates over which projects are worthy of funding can be heated and complex. While those who make big funding decisions try to be as objective as possible, the physicist Bruce Knuteson of the Massachusetts Institute of Technology in the US believes that agencies would have a much better idea of where to spend their money if they quantified the “scientific merit” of particular research proposals. He has shown how to calculate such a quantity and has also demonstrated that it is often lesser-known experiments that lead to the biggest discoveries.

In formulating scientific merit, Knuteson used the principles of information theory originally put forward by the American mathematician Claude Shannon in the 1940s. According to Shannon, the merit of a particular result from a scientific experiment is simply a measure of how improbable that result was considered to be before the experiment was carried out — in other words how much new information it generates. The merit of a proposed experiment is then equal to the combined weighted merit of all of its possible results.

Results rarely clear-cut

To convert this concept into a form that could be used to assess research proposals in practice, Knuteson also took into account the fact that experiments do not always generate clear-cut results. So an experiment might have a certain merit if it can be used to look for a hitherto undiscovered particle, but this merit would be reduced if the experiment could not definitively rule the new particle in or out.

Even sporting a multi-billion dollar price tag, the LHC is reasonable value for money compared to alternatives

Knuteson applied his thinking to assess both the merit of future experiments and the merit of past research (arXiv:0712.3572). In the former category he also took his figure of merit and divided it by the cost of the experiment to work out the project’s “bang per buck”. He found that the Large Hadron Collider, which is due to switch on at the CERN laboratory in Geneva later this year, has huge merit because it will be capable of so many potential discoveries. He pointed out that in general his measure of scientific merit rewards experiments that guarantee themselves surprises by pushing the energy boundary. “Even sporting a multi-billion dollar price tag, the LHC is reasonable value for money compared to alternatives,” he added.

Regarding past results, Knuteson calculated that the unexpected discoveries of the tau lepton and the J/psi particle in the 1970s were far more worthwhile than the higher profile but more predictable discoveries of the W and Z bosons and the top quark. He noted that the groups responsible for the latter discoveries were significantly larger, and therefore capable of promoting their results more widely. Knuteson also adds that a non-discovery of the Higgs boson at CERN will be far more worthwhile than the particle’s discovery, since a non-discovery would be more surprising.

Woolly arguments

According to Knuteson, high-energy funding agencies should require grant applicants to provide a figure of merit for their proposed experiments, adding that doing so will “tighten” the often “woolly” arguments found in proposals. While limiting his analysis to high-energy physics (since, he says, it is a rare example of a field that does not have to take account of potential, economic or social return), he concedes that even within the confines of his field the technique has its problems.

For one thing it assumes agreement on what are “qualitatively new” discoveries, pointing out, for example, that the discovery of a new type of meson might be unanticipated but would add very little to our understanding of nature. He also recognizes that some will object to the whole idea of trying to quantify the scientific merit of experiments. But this, he said, is already done by funding agencies, even if the process is implicit rather than explicit. He believes it is better if these evaluations are made “in the sharpest, most open, most quantifiable and scientifically best motivated framework possible.”

Cosmic strings in a test tube?

Researchers in the UK and Finland claim to have simulated some possible aspects of the early universe in a test tube of liquid helium-3. The experiment, which involves “colliding” the boundaries between two different phases of superfluid helium, is analogous to what may have happened shortly after the Big Bang, when some physicists believe that membranes or “branes” permeating multidimensional space collided with each other.

Physicists believe that a rapid expansion of the universe occured about 10–35 s after the Big Bang. Proponents of the string theory of particle physics have suggested that this “inflation” was brought about by the collision and subsequent annihilation of a D-brane and an anti-D-brane. D-branes are a mathematical consequence of string theory and are hypersurfaces in multidimensional space — in our familiar 3D world, for example, a 2D-brane would be a membrane like the skin of a balloon.

String-theorists believe that D-branes have zero thickness but a huge mass, and would therefore give off a tremendous amount of energy when they annihilate with each other. But string theory has yet to be proven experimentally and it remains an extremely contentious issue amongst some particle physicists and cosmologists.

Now, Richard Haley and colleagues at Lancaster University and the Helsinki University of Technology have come up with an experiment that they claim is the closest analogue system to colliding branes and anti-branes in the early universe (Nature Physics doi:10.1038/nphys815). While their system could shed some light on what might happen during such collisions, Haley told physicsworld.com that their experiment is by no means a test of string theory.

Phase boundaries collide

The team cooled several millilitres of liquid helium-3 to about 150 µK in a test tube-like sample holder. A magnetic-field gradient was applied to the sample, which created a sandwich of two different phases of superfluid helium: a region of phase “A” in the middle of the test tube and regions of phase “B” at both ends. The A and B regions were separated by phase boundaries, with the boundary from B to A being analogous to a brane and the boundary from A to B analogous to an anti-brane.

The team then changed the field gradient on the sample to reduce the thickness of the A region until the “brane” and “anti-brane” collided and annihilated, leaving just the B phase.

Helium-3 becomes a superfluid at very low temperatures because individual atoms pair up to form “Cooper pairs”. To study the remaining B phase the team used a heater at the bottom of the tube to create a stream of broken Cooper pairs that flowed up the tube.

While the B phase should be isotropic — in other words, have no structure — the broken pairs appeared to scatter off structures as they passed through the test tube. Haley and colleagues think these structural “defects” in the B phase are vortices of swirling helium created during the annihilation, similar to the defects in the form of “cosmic strings” that string theorists think were created when D-branes collided in the early Universe.

This is not the first time that helium-3 has been proposed as an experimental analogue of the early universe. One of the leading proponents of such analogies — Grisha Volovik of the Helsinki University of Technology — told physicsworld.com that Haley and colleagues have managed to simulate brane collision and test whether strings will be created.

Do branes really exist?

Volovik, who was not involved in the experiment, is adamant that the work is neither a test of string theory nor a test of whether brane annihilation was responsible for inflation. “[The experiment] confirmed the possibility of the creation of topological defects in the process of brane collision, but this does not mean that branes really exist,” he said.

Haley, who is currently rebuilding the experiment to allow the team to better characterize the defects, agrees that the team has not come up with a test of string theory. Indeed, the researchers originally set out to study the phase transition between A and B and only began speaking to the cosmologists when they realized that there may be a connection between defects in the B phase and cosmic strings.

‘Spin ice’ could contain magnetic monopoles

Particles carrying isolated north or south magnetic poles, otherwise known as magnetic monopoles, are often conjured in theory but have never been seen in experiment. Now, physicists in the US, UK and Germany say that such monopoles should exist in exotic magnetic materials called “spin ices”. Although direct applications are still a way off, learning how to move these monopoles might lead to magnetic analogues of electric circuits for making high-density magnetic memories.

Magnets always have a north and a south pole. Break one in two, and a north and south pole spontaneously form to create two new magnetic dipoles — a phenomenon that extends right down to the subatomic level. But electric fields can originate from a single pole, so why shouldn’t magnetic monopoles be isolated too?

As far back as 1931 Paul Dirac suggested that magnetic monopoles could explain the yet-unsolved mystery of quantization of electric charge, and some present theories have invoked them in order to unify the electroweak and strong interactions. Unfortunately, the masses of the monopoles in these grand unified theories are too large — about 1016 GeV — to be glimpsed by particle accelerators.

The ice rule

Claudio Castelnovo of Princeton University and colleagues at the Max-Planck Institute for the Physics of Complex Systems and Oxford University think they might be found in spin ices, materials containing an array of magnetic moments or spins arranged on a lattice of tetrahedra (see figure). The spins can point either into or out of the tetrahedra, but always obey the “ice rule” — that is, there must be two pointing in and two out. “This rule is a reference to a precise analogy with the physics of ordinary ice, where electric dipole moments behave in the same way,” team leader Shivaji Sondhi of Princeton told physicsworld.com.

What is special about spin ice, as opposed to all other magnetic materials, is that the ice rule leads to an exponentially large number of ground states, or lowest energy configurations. Normally these configurations consist of closed loops of magnetic moments, but in excited states the loops are broken and the ends behave as independently moving magnetic monopoles (Nature 451 42). “In other magnetic materials, similar incipient particles are bound in pairs, or confined,” said Sondhi.

Unlike free electrical charges, these monopoles have limited movement and so could not be used to produce a steady magnetic current. However, according to a comment article in Nature by Oleg Tchernyshyov of Johns Hopkins University in Baltimore, they could be used to produce an alternating magnetic current. “Learning how to move magnetic monopoles around would be a step towards technologies such as magnetic analogues of electric circuits and magnetic memories operating on the atomic scale,” he says.

China passes law to encourage innovative research

China’s Congress has passed a law that aims to allow scientists to tackle difficult research problems without jeopardizing their funding if they fail, Chinese media have reported. It is hoped that the law will increase the amount of innovative research done in China, while reducing the number of cases of scientific fraud.

The law, which is an amendment to the 1993 law on science and technology progress, will come take effect from July. It states that China “encourages scientists and technicians to freely explore innovation and bravely shoulder risks.” It adds that failures to get results in high-risk areas of research will be tolerated if scientists can provide evidence that they have tried their best.

Most scientific research in China is funded by the government through bodies such as the Ministry of Science and Technology or the National Natural Science Foundation of China. To help make fair decisions regarding funding applications for such research, a new “credit database” will be introduced. Scientists in China have often been convicted of falsifying data in the past, which is thought to be due in part to fears of losing funding.

“Failure is the mother of success,” said Li Yuan, a Chinese legislature official, according to China’s Xinhua news agency. “It will help create a relaxed academic atmosphere enabling scientists and technicians to take scientific risks.”

The law, which was drafted last year, will also give the patent rights of most government-sponsored research programmes to the researchers. In addition, the government will promote high-tech enterprises by giving them favourable taxation and fund-raising policies.

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