It could be a scenario from science fiction, but it really happened 130 million years ago -- in the NGC 4993 galaxy in the Hydra constellation, at a time here on Earth when dinosaurs still ruled, and flowering plants were only just evolving.

Today, dozens of UK scientists – including researchers from the University of Cambridge – and their international collaborators representing 70 observatories worldwide announced the detection of this event and the significant scientific firsts it has revealed about our Universe.

Those ripples in space finally reached Earth at 1.41pm UK time, on Thursday 17 August 2017, and were recorded by the twin detectors of the US-based Laser Interferometer Gravitational-wave Observatory (LIGO) and its European counterpart Virgo.

A few seconds later, the gamma-ray burst from the collision was recorded by two specialist space telescopes, and over following weeks, other space- and ground-based telescopes recorded the afterglow of the massive explosion. UK developed engineering and technology is at the heart of many of the instruments used for the detection and analysis.

Studying the data confirmed scientists’ initial conclusion that the event was the collision of a pair of neutron stars – the remnants of once gigantic stars, but collapsed down into approximately the size of a city. “These objects are made of matter in its most extreme, dense state, standing on the verge of total gravitational collapse,” said Michalis Agathos, from Cambridge’s Department of Applied Mathematics and Theoretical Physics. “By studying subtle effects of matter on the gravitational wave signal, such as the effects of tides that deform the neutron stars, we can infer the properties of matter in these extreme conditions.”

There are a number of “firsts” associated with this event, including the first detection of both gravitational waves and electromagnetic radiation (EM) - while existing astronomical observatories “see” EM across different frequencies (eg, optical, infra-red, gamma ray etc), gravitational waves are not EM but instead ripples in the fabric of space requiring completely different detection techniques. An analogy is that LIGO and Virgo “hear” the Universe.

The announcement also confirmed the first direct evidence that short gamma ray bursts are linked to colliding neutron stars. The shape of the gravitational waveform also provided a direct measure of the distance to the source, and it was the first confirmation and observation of the previously theoretical cataclysmic aftermaths of this kind of merger - a kilonova.

Additional research papers on the aftermath of the event have also produced a new understanding of how heavy elements such as gold and platinum are created by supernova and stellar collisions and then spread through the Universe. More such original science results are still under current analysis.

By combining gravitational-wave and electromagnetic signals together, researchers also used for the first time a new and novel technique to measure the expansion rate of the Universe.

While binary black holes produce “chirps” lasting a fraction of a second in the LIGO detector’s sensitive band, the August 17 chirp lasted approximately 100 seconds and was seen through the entire frequency range of LIGO — about the same range as common musical instruments. Scientists could identify the chirp source as objects that were much less massive than the black holes seen to date. In fact, “these long chirping signals from inspiralling neutron stars are really what many scientists expected LIGO and Virgo to see first,” said Christopher Moore, researcher at CENTRA, IST, Lisbon and member of the DAMTP/Cambridge LIGO group. “The shorter signals produced by the heavier black holes were a spectacular surprise that led to the awarding of the 2017 Nobel prize in physics.”

UK astronomers using the VISTA telescope in Chile were among the first to locate the new source. “We were really excited when we first got notification that a neutron star merger had been detected by LIGO,” said Professor Nial Tanvir from the University of Leicester, who leads a paper in Astrophysical Journal Letters today. “We immediately triggered observations on several telescopes in Chile to search for the explosion that we expected it to produce. In the end, we stayed up all night analysing the images as they came in, and it was remarkable how well the observations matched the theoretical predictions that had been made.”

“It is incredible to think that all the gold in the Earth was probably produced by merging neutron stars, similar to this event that exploded as kilonovae billions of years ago.”

“Not only is this the first time we have seen the light from the aftermath of an event that caused a gravitational wave, but we had never before caught two merging neutron stars in the act, so it will help us to figure out where some of the more exotic chemical elements on Earth come from,” said Dr Carlos Gonzalez-Fernandez of Cambridge’s Institute of Astronomy, who processed the follow-up images taken with the VISTA telescope.

“This is a spectacular discovery, and one of the first of many that we expect to come from combining together information from gravitational wave and electromagnetic observations,” said Nathan Johnson-McDaniel, researcher at DAMTP, who contributed to predictions of the amount of ejected matter using the gravitational wave measurements of the properties of the binary.

Though the LIGO detectors first picked up the gravitational wave in the United States, Virgo, in Italy, played a key role in the story. Due to its orientation with respect to the source at the time of detection, Virgo recovered a small signal; combined with the signal sizes and timing in the LIGO detectors, this allowed scientists to precisely triangulate the position in the sky. After performing a thorough vetting to make sure the signals were not an artefact of instrumentation, scientists concluded that a gravitational wave came from a relatively small patch of the southern sky.

“This event has the most precise sky localisation of all detected gravitational waves so far,” says Jo van den Brand of Nikhef (the Dutch National Institute for Subatomic Physics) and VU University Amsterdam, who is the spokesperson for the Virgo collaboration. “This record precision enabled astronomers to perform follow-up observations that led to a plethora of breath-taking results.”

Fermi was able to provide a localisation that was later confirmed and greatly refined with the coordinates provided by the combined LIGO-Virgo detection. With these coordinates, a handful of observatories around the world were able, hours later, to start searching the region of the sky where the signal was thought to originate. A new point of light, resembling a new star, was first found by optical telescopes. Ultimately, about 70 observatories on the ground and in space observed the event at their representative wavelengths. “What I am most excited about, personally, is a completely new way of measuring distances across the universe through combining the gravitational wave and electromagnetic signals. Obviously, this new cartography of the cosmos has just started with this first event, but I just wonder whether this is where we will see major surprises in the future,” said Ulrich Sperhake, Head of Cambridge’s gravitational wave group in LIGO.

In the weeks and months ahead, telescopes around the world will continue to observe the afterglow of the neutron star merger and gather further evidence about its various stages, its interaction with its surroundings, and the processes that produce the heaviest elements in the universe.

Reference: 
Physical Review Letters
"GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral."

Science
"A Radio Counterpart to a Neutron Star Merger."
"Swift and NuSTAR observations of GW170817: detection of a blue kilonova."
"Illuminating Gravitational Waves: A Concordant Picture of Photons from a Neutron Star Merger."

Astrophysical Journal Letters
"Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A."
"Multi-Messenger Observations of a Binary Neutron Star Merger."

Nature
"A gravitational-wave standard siren measurement of the Hubble constant."

Adapted from STFC and LIGO press releases. 

Latest research has found that several common flower species have nanoscale ridges on the surface of their petals that meddle with light when viewed from certain angles.

These nanostructures scatter light particles in the blue to ultraviolet colour spectrum, generating a subtle optical effect that scientists have christened the ‘blue halo’.

By manufacturing artificial surfaces that replicated ‘blue halos’, scientists were able to test the effect on pollinators, in this case foraging bumblebees. They found that bees can see the blue halo, and use it as a signal to locate flowers more efficiently.

While the ridges and grooves on a petal surface line up next to each other “like a packet of dry spaghetti”, when analysing different flower species the researchers discovered these striations vary greatly in height, width and spacing – yet all produce a similar ‘blue halo’ effect.

In fact, even on a single petal these light-manipulating structures were found to be surprisingly irregular. This is a phenomenon physicists describe as ‘disorder’.

The researchers conclude that these “messy” petal nanostructures likely evolved independently many times across flowering plants, but reached the same luminous outcome that increases visibility to pollinators – an example of what’s known as ‘convergent evolution’.

The study was conducted by a multidisciplinary team of scientists from the University of Cambridge’s departments of plant sciences, chemistry and physics along with colleagues from the Royal Botanic Gardens Kew and the Adolphe Merkele Institute in Switzerland.

The findings are published today in the journal Nature. 

“We had always assumed that the disorder we saw in our petal surfaces was just an accidental by-product of life – that flowers couldn’t do any better,” said senior author Prof Beverley Glover, plant scientist and director of Cambridge’s Botanic Garden. 

“It came as a real surprise to discover that the disorder itself is what generates the important optical signal that allows bees to find the flowers more effectively.”

“As a biologist, I sometimes find myself apologising to physicist colleagues for the disorder in living organisms – how generally messy their development and body structures can seem.”

“However, the disorder we see in petal nanostructures appears to have been harnessed by evolution and ends up aiding floral communication with bees,” Glover said.

All flowering plants belong to the ‘angiosperm’ lineage. Researchers analysed some of the earliest diverging plants from this group, and found no halo-producing petal ridges.

However, they found several examples of halo-producing petals among the two major flower groups (monocots and eudicots) that emerged during the Cretaceous period over 100 million years ago – coinciding with the early evolution of flower-visiting insects, in particular nectar-sucking bees.

“Our findings suggest the petal ridges that produce ‘blue halos’ evolved many times across different flower lineages, all converging on this optical signal for pollinators,” said Glover. 

Species which the team found to have halo-producing petals included Oenothera stricta (a type of Evening Primrose), Ursinia speciosa (a member of the Daisy family) and Hibiscus trionum (known as ‘Flower-of-the-hour’).

All the analysed flowers revealed significant levels of apparent ‘disorder’ in the dimensions and spacing of their petal nanostructures. 

“The huge variety of petal anatomies, combined with the disordered nanostructures, would suggest that different flowers should have different optical properties,” said Dr Silvia Vignolini, from Cambridge’s Department of Chemistry, who led the study’s physics team.

“However, we observed that all these petal structures produce a similar visual effect in the blue-to-ultraviolet wavelength region of the spectrum – the blue halo.”

Previous studies have shown that many species of bee have an innate preference for colours in the violet-blue range. However, plants do not always have the means to produce blue pigments.

“Many flowers lack the genetic and biochemical capability to manipulate pigment chemistry in the blue to ultraviolet spectrum,” said Vignolini. “The presence of these disordered photonic structures on their petals provides an alternative way to produce signals that attract insects.”  

The researchers artificially recreated ‘blue halo’ nanostructures and used them as surfaces for artificial flowers. In a “flight arena” in a Cambridge lab, they tested how bumblebees responded to surfaces with and without halos.

Their experiments showed that bees can perceive the difference, finding the surfaces with halos more quickly – even when both types of surfaces were coloured with the same black or yellow pigment.

Using rewarding sugar solution in one type of artificial flower, and bitter quinine solution in the other, the scientists found that bees could use the blue halo to learn which type of surface had the reward.    

“Insect visual systems are different to human ones,” explains Edwige Moyroud, from Cambridge’s Department of Plant Sciences and the study’s lead author. “Unlike us, bees have enhanced photoreceptor activity in the blue-UV parts of the spectrum.”

“Humans can identify some blue halos – those emanating from darkly pigmented flowers. For example the ‘black’ tulip cultivar, known as ‘Queen of the night’.”

“However, we can’t distinguish between a yellow flower with a blue halo and one without – but our study found that bumblebees can,” she said.

The team say the findings open up new opportunities for the development of surfaces that are highly visible to pollinators, as well as exploring just how living plants control the levels of disorder on their petal surfaces. “The developmental biology of these structures is a real mystery,” added Glover.  

The clock is ticking for the UK in terms of research funding from the EU.

Horizon 2020, the current framework programme, has provided an increasingly important source of funds for universities in the UK. Until recently, despite the uncertainties surrounding the UK’s preparations to withdraw from the EU, UK-based researchers were still being encouraged to apply for H2020 funding. But earlier this month an explicit warning shot was fired across the researchers’ bows. Now, although UK-based researchers are still able to apply, there is the qualification that “the eligibility criteria must be complied with for the entire duration of the grant.” As things stand, the key eligibility criterion that is likely to fail to be met after the 29th March 2019 concerns researchers’ mobility.

No one should be in any doubt that the EU is prepared to enforce this ruling. It did it before when Switzerland’s own referendum meant that workers from Croatia were not freely able to enter the country, and it took quite a lot of fudging to resolve that. Switzerland, like the UK, is one of the most successful of countries when it comes to EU science funding. The country was really keen to find a work-around to enable them to be fully eligible for Horizon 2020 funding, and the issue was resolved relatively swiftly. It would be nice to think that a similar degree of pragmatism might apply to save the UK’s scientific research bacon, but it isn’t clear that this will happen.

Whether the UK can retain access to the Horizon2020 programme –and if so, on what terms— is just one tiny part of the intricate Brexit negotiations. The importance of EU funding for research does appear to have impinged on some ministers’ minds. It does get talked about. But mobility of researchers is a tricky problem, because worker mobility was such a central plank in the referendum campaigns.

Immigration is an emotive subject, and it is hard to envisage a scheme that enabled scientists to travel across EU borders freely while preventing other workers from sharing that luxury.  It isn’t at all clear that mobility restricted to researchers would be sufficient to satisfy the EU, and thus ensure that the UK was still eligible.

As a member of the European Research Council’s Scientific Council I am very aware of the importance of ERC funding (a key part of the Horizon 2020 programme). The University of Cambridge hosts more ERC grants than any other university in Europe. It currently manages 209 grants, representing a substantial slice of the total research funding the University receives.

It isn’t only the pure financial worth that matters, but also the prestige associated with winning such funding. Those who believe that all will be resolved if the UK government can find some funding to plug the gap in science research budgets if/when the UK is excluded from the programme, ignore this crucial point. (‘Science’ in this case should be recognized as encompassing not just the natural sciences and engineering, but also the social sciences and arts and humanities). No existing national scheme within the UK confers equivalent prestige – at promotions and appointments committees for instance – as an ERC grant. It is hard to see a purely national scheme ever doing so.

Of course, the consequences of Brexit do not simply relate to money. There are huge implications for the people whose futures will be immediately and directly affected through their specific status as citizens. The uncertainty, and accompanying anxiety, is huge.  Individuals and families from other EU states do not know what their rights will be. Some are walking away already, not applying from the mainland continent as jobs open up in the UK, or choosing not to stay at the end of one contract even if opportunities are open to them.

As the deadline of March 2019 approaches, we do not know how individuals will weigh up the pros and cons of staying in the UK in what may feel like an increasingly hostile environment. Nor do we know how they will feel about not knowing what steps they might have to take to enable them to continue to live here— regardless of how long they have already been resident. Individual decisions will no doubt be decided by individual circumstances; some may feel it preferable to stay (or to come) as it is the best short-term way of meeting their career aspirations.

But science thrives on easy mobility, the exchange of ideas facilitated by the exchange of people, specific technical skills transmitted by the hands that practise them. It has to be expected that the UK’s leading role in science, where we punch far above our weight, is likely to be significantly and negatively impacted by the loss of easy researcher mobility.

Finally, there is the question of what happens to student numbers. Calculations suggest some universities, including Cambridge, are not likely to see a dip in income from student fees even though it is expected that the numbers of EU students will drop substantially.

One of the ironies in this process is that, had the Home Office been willing to remove international students from the immigration figures before the referendum, the result may well have gone the other way: with students excluded, official “immigration” numbers would have appeared lower. Even now, there remains an official determination to retain students in the immigration figures –despite it being so hard to find anyone (from any party) exhibiting much enthusiasm for doing so.

All in all, universities are facing uncertain times. As a member of a sector that has brought much wealth and prestige to the UK, and attracted students and researchers from around the world to enjoy our first class labs, libraries and lectures, it is deeply depressing to watch our strengths being challenged in ways it is not easy to address.

Cambridge has for decades been a truly international university and we will no doubt continue to thrive as such, however much the composition of its membership may change. But to see our funding, our staff and students being so immediately affected by political decisions taken elsewhere is a major concern.

*Professor Dame Athene Donald is Master of Churchill College.This text is based on her Sir Hermann Bondi Lecture, delivered on 23 October as part of the Cambridge Festival of Ideas.

The printing-based approach, jointly developed by researchers at the University of Cambridge and the Hitachi Cambridge Laboratory, combines high-resolution inkjet printing with nanophotonics – the study and harnessing of light on the scale of a billionth of a metre – the first time that this combination has been successfully demonstrated. The results are reported in the journal Advanced Materials.

Over the last decade, inkjet printing – the same basic technology that many of us have in our homes – has advanced to the point where it can be used to print very small devices, using a range of printable materials, including living cells, as ‘ink’. This approach is both simple and low-cost, and it is widely used in electronics and biotechnology.

“Most inkjet printers push the ink through the nozzle by heating or applying pressure, producing ink droplets about the size of the diameter of a human hair,” said the paper’s co-first author Dr Vincenzo Pecunia, a former PhD student and postdoctoral researcher, and now visiting researcher, at the University’s Cavendish Laboratory.

Pecunia’s research focuses on printable optoelectronic materials for a range of applications, and his group recently obtained a printer based on electrohydrodynamic jets: a long word that essentially means a printer capable of ultra-high resolution printing. Instead of relying on pressure or heat, this type of printer applies a voltage to the ink, providing enough force to push it through a much smaller nozzle, producing ultra-small ink droplets – ten to a hundred times smaller than those produced by conventional printers.

Thanks to a chance meeting between Pecunia and co-first author Dr Frederic Brossard from the Hitachi Cambridge Laboratory, the researchers found that the new printer could print structures small enough to be used in nanophotonics, which is Brossard’s area of research.

“Previous efforts to combine these two areas had bumped into the limitations of conventional inkjet printing technology, which cannot directly deposit anything small enough to be comparable to the wavelength of light,” said Pecunia. “But through electrodynamic inkjet printing we’ve been able to move beyond these limitations.”

The researchers were able to deposit ultra-small ink droplets onto photonic crystals. The ink droplets are small enough that they can be ‘drawn’ on the crystals on demand as if from a very fine pen, and locally change the properties of the crystals so that light could be trapped. This technique enables the creation of many types of patterns onto the photonic crystals, at high speed and over a large area. Additionally, the patterns can be made of all sorts of printable materials, and the method is scalable, low-cost, and the photonic crystal is reusable since the ink can be simply washed away.

“This fabrication technique opens the door for diverse opportunities in fundamental and applied sciences,” said Brossard. “A potential direction is the creation of a high density of highly sensitive sensors to detect minute amounts of biomolecules such as viruses or cancer cells. This could also be a very useful tool to study some fundamental phenomena requiring very strong interaction between light and matter in new materials and create lasers on demand. Finally, this technology could also enable the creation of highly compact optical circuits which would guide the light and which could be modified by inkjet printing using the photonic crystal template.”

The research was funded in part by the Engineering and Physical Sciences Research Council (EPSRC) and the Science and Technology Facilities Council (STFC).

Reference
Frederic S.F. Brossard et al. ‘Inkjet printed nanocavities on a photonic crystal template.’ Advanced Materials (2017). DOI: 10.1002/adma.201704425

The Global Alliance was formed in 2016 as a tripartite agreement between University of California, Berkeley, the University of Cambridge, and National University of Singapore in order to develop innovative research across the three universities to address research questions that could not be answered by one institution alone. There are three themes within the Global Alliance: Precision Medicine, Cities, and Smart Systems.

Following a second funding call in May 2017, the Management Selection Committee has approved funding of the following five collaborative research projects:

• "Opportunities for ecological adaptation to flood hazards in major global cities: London, Singapore and San Francisco" (Principal Investigator: Professor Thomas Spencer)
• "Machine learning tools for personalised diagnosis in dementia"  (Principal Investigator: Professor Zoe Kourtzi)
• "Healthy living in cities: my Personal Exposure Quality (MyPEQ)" (Principal investigator: Professor Rajasekhar Balasubramanian)
• "Automating Approaches for Clinical Genome Interpretation" (Principal Investigator: Professor Steven  Brenner)
• "Skin Deformation Assay Platforms for Pathogen- and Patient-Specific Diagnostics and Drug Development" (Principal Investigator: Dr Katherine Brown)

The three universities are delighted to approve these collaborative projects which will build upon the combined strengths of the universities, as well as their distinctive regional insights, to develop unique solutions to global problems.

Professor Paul Alivisatos, Executive Vice Chancellor and Provost, University of California, Berkeley

Professor Chris Abell, Pro-Vice-Chancellor for Research, University of Cambridge

Professor Ho Teck Hua, Senior Deputy President and Provost Designate, National University of Singapore

Think you know what gravity is? Think again. New research is revealing how little we know about this most mysterious of forces. Read the rest of the article from the latest version of CAM, the University's alumni magazine, here.

The Dolby family gift is the largest philanthropic donation ever made to UK science, and will support the Cavendish Laboratory, the world-leading centre for physics research where Ray Dolby received his PhD in 1961. Thanks to this exceptional gift, the University has now surpassed the £1 billion milestone in its current £2 billion fundraising campaign. This is the second generous gift to Cambridge from the Dolby family, who donated £35 million to Pembroke College, Cambridge in 2015. The Dolby family is now the largest donor to the fundraising campaign, and the second-largest donor to the University in its 808-year history.

In recognition of this gift, the flagship building of the Cavendish Laboratory redevelopment will be named the Ray Dolby Centre, and is expected to open in 2022. In addition, a new Ray Dolby Research Group will be established at the Cavendish, which will significantly expand research capability and expertise within the new building. The group, which will be led by a new endowed Ray Dolby Professorship, will build on and further strengthen the Cavendish Laboratory’s status and impact as one of the greatest centres of physics research in the world.

“This unparalleled gift is a fitting tribute to Ray Dolby’s legacy, who changed the way the world listened - his research paved the way for an entire industry,” said Cambridge Vice-Chancellor Professor Stephen Toope. “A century from now, we can only speculate on which discoveries will alter the way we live our lives, and which new industries will have been born in the Cavendish Laboratory, in large part thanks to this extraordinarily generous gift.”

“The Ray Dolby Centre will complete the development of the new Cavendish Laboratory. In addition to serving as a home for physics research at Cambridge, it will be a top-class facility for the nation,” said Professor Andy Parker, Head of the Cavendish Laboratory. “This extremely generous gift from the Dolby family is the most significant investment in physics research in generations, and a truly transformational gift in Cambridge’s history.”

“The University of Cambridge played a pivotal role in Ray’s life, both personally and professionally,” said Dolby’s widow, Dagmar. “At Cambridge and at the Cavendish, he gained the formative education and insights that contributed greatly to his lifelong groundbreaking creativity, and enabled him to start his business.”

“My father’s time at the Cavendish provided him with an environment where he got a world-class education in physics, and many of his successful ideas about noise reduction were stimulated by his Cambridge experience,” said Dolby’s son David. “Our family is pleased to be able to support the future scientists and innovators who will benefit from the thoughtfully designed Ray Dolby Centre.”

Ray Dolby, who died in 2013 at the age of 80, came to Cambridge as a Marshall Scholar in 1957. He received his PhD from the Cavendish in 1961, and was a student and later a Fellow of Pembroke College.

In 1965, he founded Dolby Laboratories in London and invented the Dolby System, an analogue audio encoding system that forever improved the quality of recorded sound. He moved the company in 1976 to San Francisco, where it has been headquartered ever since.

The new Cavendish Laboratory will be its third home since its founding in 1874, and was first announced by the government in its 2015 Spending Review. It promised a £75 million investment in the Cavendish, which has been confirmed today, helping maintain Britain’s position at the forefront of physical sciences research. The funding will be delivered by the Engineering and Physical Sciences Research Council (EPSRC). Work on the new facility is expected to begin in 2019.

“This generous £85 million donation from the Ray Dolby estate along with the £75 million government has already pledged is a testament to the importance of this facility and the UK’s leadership in science,” said Science Minister Jo Johnson. “The UK is one of the most innovative countries in the world, and through our Industrial Strategy and additional £2.3 billion investment for research and development we are ensuring our world-class research base goes from strength to strength for years to come.”

“A successful nation invests in science, and this grant signals our intent to lead the world,” said Professor Philip Nelson, EPSRC's Chief Executive. “The facilities will be open to researchers across the country and encourage collaborative working between academics and institutions. Clearly Ray Dolby valued the university that nurtured his talents and, in making his bequest, has made a truly generous contribution to future generations.”

Inset image: Ray Dolby

Read more about how clinical researchers, physicists, engineers and social scientists are among those collaborating as part of the Cancer Research UK Early Detection Programme.

One of the fundamental ideas of quantum theory is that quantum objects can exist both as a wave and as a particle, and that they don’t exist as one or the other until they are measured. This is the premise that Erwin Schrödinger was illustrating with his famous thought experiment involving a dead-or-maybe-not-dead cat in a box.

“This premise, commonly referred to as the wave function, has been used more as a mathematical tool than a representation of actual quantum particles,” said David Arvidsson-Shukur, a PhD student at Cambridge’s Cavendish Laboratory, and the paper’s first author. “That’s why we took on the challenge of creating a way to track the secret movements of quantum particles.”

Any particle will always interact with its environment, ‘tagging’ it along the way. Arvidsson-Shukur, working with his co-authors Professor Crispin Barnes from the Cavendish Laboratory and Axel Gottfries, a PhD student from the Faculty of Economics, outlined a way for scientists to map these ‘tagging’ interactions without looking at them. The technique would be useful to scientists who make measurements at the end of an experiment but want to follow the movements of particles during the full experiment.

Some quantum scientists have suggested that information can be transmitted between two people – usually referred to as Alice and Bob – without any particles travelling between them. In a sense, Alice gets the message telepathically. This has been termed counterfactual communication because it goes against the accepted ‘fact’ that for information to be carried between sources, particles must move between them.

“To measure this phenomenon of counterfactual communication, we need a way to pin down where the particles between Alice and Bob are when we’re not looking,” said Arvidsson-Shukur. “Our ‘tagging’ method can do just that. Additionally, we can verify old predictions of quantum mechanics, for example that particles can exist in different locations at the same time.”

The founders of modern physics devised formulas to calculate the probabilities of different results from quantum experiments. However, they did not provide any explanations of what a quantum particle is doing when it’s not being observed. Earlier experiments have suggested that the particles might do non-classical things when not observed, like existing in two places at the same time. In their paper, the Cambridge researchers considered the fact that any particle travelling through space will interact with its surroundings. These interactions are what they call the ‘tagging’ of the particle. The interactions encode information in the particles that can then be decoded at the end of an experiment, when the particles are measured.

The researchers found that this information encoded in the particles is directly related to the wave function that Schrödinger postulated a century ago. Previously the wave function was thought of as an abstract computational tool to predict the outcomes of quantum experiments. “Our result suggests that the wave function is closely related to the actual state of particles,” said Arvidsson-Shukur. “So, we have been able to explore the ‘forbidden domain’ of quantum mechanics: pinning down the path of quantum particles when no one is observing them.”

Reference
D. R. M. Arvidsson-Shukur, C. H. W. Barnes, and A. N. O. Gottfries. ‘Evaluation of counterfactuality in counterfactual communication protocols’. Physical Review A (2017). DOI: 10.1103/PhysRevA.96.062316

As the global population increases, so too does energy demand. The threat of climate change means that there is an urgent need to find cleaner, renewable alternatives to fossil fuels that do not contribute extensive amounts of greenhouse gases with potentially devastating consequences on our ecosystem. Solar power is considered to be a particularly attractive source as on average the Earth receives around 10,000 times more energy from the sun in a given time than is required by human consumption.

In recent years, in addition to synthetic photovoltaic devices, biophotovoltaics (BPVs, also known as biological solar-cells) have emerged as an environmentally-friendly and low-cost approach to harvesting solar energy and converting it into electrical current. These solar cells utilise the photosynthetic properties of microorganisms such as algae to convert light into electric current that can be used to provide electricity.

During photosynthesis, algae produce electrons, some of which are exported outside the cell where they can provide electric current to power devices. To date, all the BPVs demonstrated have located charging (light harvesting and electron generation) and power delivery (transfer to the electrical circuit) in a single compartment; the electrons generate current as soon as they have been secreted.

In a new technique described in the journal Nature Energy, researchers from the departments of Biochemistry, Chemistry and Physics have collaborated to develop a two-chamber BPV system where the two core processes involved in the operation of a solar cell – generation of electrons and their conversion to power – are separated.

“Charging and power delivery often have conflicting requirements,” explains Kadi Liis Saar, of the Department of Chemistry. “For example, the charging unit needs to be exposed to sunlight to allow efficient charging, whereas the power delivery part does not require exposure to light but should be effective at converting the electrons to current with minimal losses.”

Building a two-chamber system allowed the researchers to design the two units independently and through this optimise the performance of the processes simultaneously.

“Separating out charging and power delivery meant we were able to enhance the performance of the power delivery unit through miniaturisation,” explains Professor Tuomas Knowles from the Department of Chemistry and the Cavendish Laboratory. “At miniature scales, fluids behave very differently, enabling us to design cells that are more efficient, with lower internal resistance and decreased electrical losses.”

The team used algae that had been genetically modified to carry mutations that enable the cells to minimise the amount of electric charge dissipated non-productively during photosynthesis. Together with the new design, this enabled the researchers to build a biophotovoltaic cell with a power density of 0.5 W/m2, five times that of their previous design. While this is still only around a tenth of the power density provided by conventional solar fuel cells, these new BPVs have several attractive features, they say.

"While conventional silicon-based solar cells are more efficient than algae-powered cells in the fraction of the sun’s energy they turn to electrical energy, there are attractive possibilities with other types of materials," says Professor Christopher Howe from the Department of Biochemistry. “In particular, because algae grow and divide naturally, systems based on them may require less energy investment and can be produced in a decentralised fashion."

Separating the energy generation and storage components has other advantages, too, say the researchers. The charge can be stored, rather than having to be used immediately – meaning that the charge could be generated during daylight and then used at night-time.

While algae-powered fuel cells are unlikely to generate enough electricity to power a grid system, they may be particularly useful in areas such as rural Africa, where sunlight is in abundance but there is no existing electric grid system. In addition, whereas semiconductor-based synthetic photovoltaics are usually produced in dedicated facilities away from where they are used, the production of BPVs could be carried out directly by the local community, say the researchers.

“This a big step forward in the search for alternative, greener fuels,” says Dr Paolo Bombelli, from the Department of Biochemistry. “We believe these developments will bring algal-based systems closer to practical implementation.”

The research was supported by the Leverhulme Trust, the Engineering and Physical Sciences Research Council and the European Research Council.

Reference
Saar, KL et al. Enhancing power density of biophotovoltaics by decoupling storage and power delivery. Nature Energy; 9 Jan 2018; DOI: 10.1038/s41560-017-0073-0

An international team led by Dr Renske Smit from the Kavli Institute of Cosmology at the University of Cambridge used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to open a new window onto the distant Universe, and have for the first time been able to identify normal star-forming galaxies at a very early stage in cosmic history with this telescope. The results are reported in the journal Nature, and will be presented at the 231^st meeting of the American Astronomical Society.

Light from distant objects takes time to reach Earth, so observing objects that are billions of light years away enables us to look back in time and directly observe the formation of the earliest galaxies. The Universe at that time, however, was filled with an obscuring ‘haze’ of neutral hydrogen gas, which makes it difficult to see the formation of the very first galaxies with optical telescopes.

Smit and her colleagues used ALMA to observe two small newborn galaxies, as they existed just 800 million years after the Big Bang. By analysing the spectral ‘fingerprint’ of the far-infrared light collected by ALMA, they were able to establish the distance to the galaxies and, for the first time, see the internal motion of the gas that fuelled their growth.

“Until ALMA, we’ve never been able to see the formation of galaxies in such detail, and we’ve never been able to measure the movement of gas in galaxies so early in the Universe’s history,” said co-author Dr Stefano Carniani, from Cambridge’s Cavendish Laboratory and Kavli Institute of Cosmology.

The researchers found that the gas in these newborn galaxies swirled and rotated in a whirlpool motion, similar to our own galaxy and other, more mature galaxies much later in the Universe’s history. Despite their relatively small size – about five times smaller than the Milky Way – these galaxies were forming stars at a higher rate than other young galaxies, but the researchers were surprised to discover that the galaxies were not as chaotic as expected.

“In the early Universe, gravity caused gas to flow rapidly into the galaxies, stirring them up and forming lots of new stars – violent supernova explosions from these stars also made the gas turbulent,” said Smit, who is a Rubicon Fellow at Cambridge, sponsored by the Netherlands Organisation for Scientific Research. “We expected that young galaxies would be dynamically ‘messy’, due to the havoc caused by exploding young stars, but these mini-galaxies show the ability to retain order and appear well regulated. Despite their small size, they are already rapidly growing to become one of the ‘adult’ galaxies like we live in today.”

The data from this project on small galaxies paves the way for larger studies of galaxies during the first billion years of cosmic time. The research was funded in part by the European Research Council and the UK Science and Technology Facilities Council (STFC).

Reference:
Renske Smit et al. ‘Rotation in [C II]-emitting gas in two galaxies at a redshift of 6.8.’ Nature (2018). DOI: 10.1038/nature24631

An international team of researchers led by the University of Cambridge found that the addition of potassium iodide ‘healed’ the defects and immobilised ion movement, which to date have limited the efficiency of cheap perovskite solar cells. These next-generation solar cells could be used as an efficiency-boosting layer on top of existing silicon-based solar cells, or be made into stand-alone solar cells or coloured LEDs. The results are reported in the journal Nature.

The solar cells in the study are based on metal halide perovskites – a promising group of ionic semiconductor materials that in just a few short years of development now rival commercial thin film photovoltaic technologies in terms of their efficiency in converting sunlight into electricity. Perovskites are cheap and easy to produce at low temperatures, which makes them attractive for next-generation solar cells and lighting.

Despite the potential of perovskites, some limitations have hampered their efficiency and consistency. Tiny defects in the crystalline structure of perovskites, called traps, can cause electrons to get ‘stuck’ before their energy can be harnessed. The easier that electrons can move around in a solar cell material, the more efficient that material will be at converting photons, particles of light, into electricity. Another issue is that ions can move around in the solar cell when illuminated, which can cause a change in the bandgap – the colour of light the material absorbs.  

“So far, we haven’t been able to make these materials stable with the bandgap we need, so we’ve been trying to immobilise the ion movement by tweaking the chemical composition of the perovskite layers,” said Dr Sam Stranks from Cambridge’s Cavendish Laboratory, who led the research. “This would enable perovskites to be used as versatile solar cells or as coloured LEDs, which are essentially solar cells run in reverse.”

In the study, the researchers altered the chemical composition of the perovskite layers by adding potassium iodide to perovskite inks, which then self-assemble into thin films. The technique is compatible with roll-to-roll processes, which means it is scalable and inexpensive. The potassium iodide formed a ‘decorative’ layer on top of the perovskite which had the effect of ‘healing’ the traps so that the electrons could move more freely, as well as immobilising the ion movement, which makes the material more stable at the desired bandgap.

The researchers demonstrated promising performance with the perovskite bandgaps ideal for layering on top of a silicon solar cell or with another perovskite layer – so-called tandem solar cells. Silicon tandem solar cells are the most likely first widespread application of perovskites. By adding a perovskite layer, light can be more efficiently harvested from a wider range of the solar spectrum.

“Potassium stabilises the perovskite bandgaps we want for tandem solar cells and makes them more luminescent, which means more efficient solar cells,” said Stranks, whose research is funded by the European Union and the European Research Council’s Horizon 2020 Programme. “It almost entirely manages the ions and defects in perovskites.”

“We’ve found that perovskites are very tolerant to additives – you can add new components and they’ll perform better,” said first author Mojtaba Abdi-Jalebi, a PhD candidate at the Cavendish Laboratory who is funded by Nava Technology Limited. “Unlike other photovoltaic technologies, we don’t need to add an additional layer to improve performance, the additive is simply mixed in with the perovskite ink.”

The perovskite and potassium devices showed good stability in tests, and were 21.5% efficient at converting light into electricity, which is similar to the best perovskite-based solar cells and not far below the practical efficiency limit of silicon-based solar cells, which is (29%). Tandem cells made of two perovskite layers with ideal bandgaps have a theoretical efficiency limit of 45% and a practical limit of 35% - both of which are higher than the current practical efficiency limits for silicon. “You get more power for your money,” said Stranks.

The research has also been supported in part by the Royal Society and the Engineering and Physical Sciences Research Council. The international team included researchers from Cambridge, Sheffield University, Uppsala University in Sweden and Delft University of Technology in the Netherlands.

Reference:
Mojtaba Abdi-Jalebi et al. ‘Maximising and Stabilising Luminescence from Halide Perovskites with Potassium Passivation.’ Nature (2018). DOI: 10.1038/nature25989

My research focuses on developing devices that can manipulate electrons one at a time. I also happen to have long gaps on my CV that take some creativity to explain in job interviews. This is because I’ve had mental health problems since I was a teenager.  During treatment for this, I’ve been privileged to meet some wonderful people with a variety of mental health conditions and to gain a little insight into their struggles.

Mental health conditions are often invisible. If I have a broken leg or a sore throat then it doesn’t take much for my colleagues to understand that I need time off work. If my mental health is bad then the onus is on me to explain to other people why I need time off work.

I worry that people will think I am silly, or oversensitive, or lazy, or skiving. However, the first person you need to convince that it’s OK to have time off is yourself. It feels like a great step forward when you do.

There are a lot of misconceptions about mental illnesses, not least because their invisibility makes awareness of their prevalence remain low. If I tell someone what mental health conditions I have, I have no idea what this will mean to them, and whether it will match the reality of how I feel. This is particularly the case in the multicultural research environment, where different cultures may have very different understandings of mental health.

As researchers we have succeeded in our University studies and got our PhDs. We are used to solving problems, achieving highly and getting stuff done.

When faced with a mental health condition, we feel desperately that we need to understand and solve the problem, and soon. But even after many years I do not fully understand my mental health problems. I cannot fix them or solve them as I would a problem in the lab.

It has taken me years to learn to spot triggers and recognise warning signs when things are getting bad, and to learn some things that sometimes help. I have learned a huge amount, but there is still much I don’t understand about this illness.

I have told few colleagues about my health problems, but those I have told have been supportive. I’ve benefited from some fantastic services at the University including the staff counselling and occupational health services. That support – at work and from family and friends – makes a huge difference.

There are still challenges – my ongoing mental health problems are classed as a disability, and that meant I had to tick a box labelling me as a “disabled person” when I started this job in order to qualify for reasonable adjustments. Not everyone would feel OK about that. These labels can create barriers to people coming forward to seek help.

Researchers often have to move around a lot to advance their careers, doing a series of short-term contracts in several places. If someone with a mental health condition comes to the UK for an 18-month postdoc job, it might take them a while to understand how to access treatment in the UK. They might wait for months to be seen by a specialist. And treatment in the UK might be very different to what they have known in in their home country.

I’ve been very lucky in this respect. When I was a PhD student, my College provided me with free accommodation near to the hospital where I was being treated so I didn’t have to move back to live with my parents and start all over again on a waiting list.

My fellowship is normally only open to people who are moving to Cambridge. But the selection panel took into account that I wanted to stay in Cambridge to continue to access treatment and support at the same clinic.

The sector needs to do more to help researchers who have moved for a job, uprooting themselves from their support networks.

Research is challenging. In trying to do things no one has ever done before there are always setbacks. For someone with a mental health condition, you can go from one setback in the lab to deep despair in the time it takes to say ‘Supercalifragilisticexpialidocious’.

Sometimes I wish having someone beside me to give moral support during difficult experiments counted as a ‘reasonable adjustment’. But I am lucky to have colleagues and a boss who do support me.

As a researcher you need to believe in your research ideas and your ability to carry them out. You need to be able to sell your research. You need to be excited by your research and be able to convince other people to get excited about it, to publish it, to fund it. This is hard to do if you are feeling depressed, and you don’t even feel like life is worth living. It’s really hard.

But friends and colleague can make a real difference in helping people with mental health problems to flourish in their research.

A greater openness about mental health in the research community will surely benefit us all.

The researchers, whose work appears in the journal Science, say their findings could be a “game changer” by allowing the energy from sunlight absorbed in these materials to be captured and used more efficiently. 

Lightweight semiconducting plastics are now widely used in mass market electronic displays such as those found in phones, tablets and flat-screen televisions.  However, using these materials to convert sunlight into electricity to make solar cells is far more complex. 

The photo-excited states – when photons of light are absorbed by the semiconducting material – need to move so that they can be “harvested” before they lose their energy.  These excitations typically only travel about 10 nanometres in plastic (or polymeric) semiconductors, so researchers need to build tiny structures patterned at the nanoscale to maximise the “harvest”.

Dr Xu-Hui Jin and colleagues at the University of Bristol developed a new way to make highly ordered crystalline semiconducting structures using polymers.

Dr Michael Price of Cambridge's Cavendish Laboratory measured the distance that the photo-exited states travelled, which reached distances of 200 nanometres – 20 times further than was previously possible.

200 nanometres is especially significant because it is greater than the thickness of material needed to completely absorb ambient light, making these polymers more suitable as “light harvesters” for solar cells and photodetectors.

“The gain in efficiency would actually be for two reasons: first, because the energetic particles travel further, they are easier to “harvest”, and second, we could now incorporate layers around 100 nanometres thick, which is the minimum thickness needed to absorb all the energy from light – the so-called optical absorption depth,” said co-author Dr George Whittell from the University of Bristol. “Previously, in layers this thick, the particles were unable to travel far enough to reach the surfaces.”

“The distance that energy can be moved in these materials comes as a big surprise and points to the role of unexpected quantum coherent transport processes,” said co-author Professor Sir Richard Friend from Cambridge's Cavendish Laboratory, and a Fellow of St John's College. 

The research team now plans to prepare structures thicker than those in the current study and greater than the optical absorption depth, with a view to building prototype solar cells based on this technology.

They are also preparing other structures capable of using light to perform chemical reactions, such as the splitting of water into hydrogen and oxygen.

Reference:
Xu-Hui Jin et al.‘Long-range exciton transport in conjugated polymer nanofibers prepared by seeded growth.’ Science (2018). DOI: 10.1126/science.aar8104 

Adapted from a University of Bristol press release. 

Researchers at the University of Cambridge and the University of Illinois at Urbana-Champaign say their lipid-scrambling DNA enzyme is the first to outperform naturally occurring enzymes – and does so by three orders of magnitude. Their findings are published in the journal Nature Communications.

“Cell membranes are lined with a different set of molecules on the inside and outside, and cells devote a lot of resources to maintaining this,” said study leader Aleksei Aksimentiev, a professor of physics at Illinois. “But at some points in a cell’s life, the asymmetry has to be dismantled. Then the markers that were inside become outside, which sends signals for certain processes, such as cell death. There are enzymes in nature that do that called scramblases. However, in some other diseases where scramblases are deficient, this doesn’t happen correctly. Our synthetic scramblase could be an avenue for therapeutics.”

Aksimentiev’s group came upon DNA’s scramblase activity when looking at DNA structures that form pores and channels in cell membranes. They used the Blue Waters supercomputer at the National Center for Supercomputing Applications at Illinois to model the systems at the atomic level. They saw that when certain DNA structures insert into the membrane – in this case, a bundle of eight strands of DNA with cholesterol at the ends of two of the strands – lipids in the membrane around the DNA begin to shuffle between the inner and outer membrane layers.

To verify the scramblase activity predicted by the computer models, Aksimentiev’s group at Illinois partnered with Professor Ulrich Keyser’s group at Cambridge. The Cambridge group synthesised the DNA enzyme and tested it in model membrane bubbles, called vesicles, and then in human breast cancer cells.

“The results show very conclusively that our DNA nanostructure facilitates rapid lipid scrambling,” said co-first author Alexander Ohmann, a PhD student in Keyser’s group in Cambridge’s Cavendish Laboratory. “Most interestingly, the high flipping rate indicated by the molecular dynamics simulations seems to be of the same order of magnitude in experiments: up to a thousand-fold faster than what has previously been shown for natural scramblases.”

On its own, the DNA scramblase produces cell death indiscriminately, said Aksimentiev. The next step is to couple it with targeting systems that specifically seek out certain cell types, a number of which have already been developed for other DNA agents.

“We are also working to make these scramblase structures activated by light or some other stimulus, so they can be activated only on demand and can be turned off,” said Aksimentiev.

“Although we have still a long way to go, this work highlights the enormous potential of synthetic DNA nanostructures with possible applications for personalised drugs and therapeutics for a variety of health conditions in the future,” said Ohmann, who has also written a blog post on their new paper.

The US National Science Foundation and the National Institutes of Health supported this work.  

Reference:
Alexander Ohmann et al. ‘A synthetic enzyme built from DNA flips 10⁷ lipids per second in biological membranes.’ Nature Communications (2018). DOI: 10.1038/s41467-018-04821-5

​Adapted from a University of Illinois at Urbana-Champaign press release.

The Dolby family gift is the largest philanthropic donation ever made to UK science, and will support the Cavendish Laboratory, the world-leading centre for physics research where Ray Dolby received his PhD in 1961. Thanks to this exceptional gift, the University has now surpassed the £1 billion milestone in its current £2 billion fundraising campaign. This is the second generous gift to Cambridge from the Dolby family, who donated £35 million to Pembroke College, Cambridge in 2015. The Dolby family is now the largest donor to the fundraising campaign, and the second-largest donor to the University in its 808-year history.

In recognition of this gift, the flagship building of the Cavendish Laboratory redevelopment will be named the Ray Dolby Centre, and is expected to open in 2022. In addition, a new Ray Dolby Research Group will be established at the Cavendish, which will significantly expand research capability and expertise within the new building. The group, which will be led by a new endowed Ray Dolby Professorship, will build on and further strengthen the Cavendish Laboratory’s status and impact as one of the greatest centres of physics research in the world.

“This unparalleled gift is a fitting tribute to Ray Dolby’s legacy, who changed the way the world listened - his research paved the way for an entire industry,” said Cambridge Vice-Chancellor Professor Stephen Toope. “A century from now, we can only speculate on which discoveries will alter the way we live our lives, and which new industries will have been born in the Cavendish Laboratory, in large part thanks to this extraordinarily generous gift.”

“The Ray Dolby Centre will complete the development of the new Cavendish Laboratory. In addition to serving as a home for physics research at Cambridge, it will be a top-class facility for the nation,” said Professor Andy Parker, Head of the Cavendish Laboratory. “This extremely generous gift from the Dolby family is the most significant investment in physics research in generations, and a truly transformational gift in Cambridge’s history.”

“The University of Cambridge played a pivotal role in Ray’s life, both personally and professionally,” said Dolby’s widow, Dagmar. “At Cambridge and at the Cavendish, he gained the formative education and insights that contributed greatly to his lifelong groundbreaking creativity, and enabled him to start his business.”

“My father’s time at the Cavendish provided him with an environment where he got a world-class education in physics, and many of his successful ideas about noise reduction were stimulated by his Cambridge experience,” said Dolby’s son David. “Our family is pleased to be able to support the future scientists and innovators who will benefit from the thoughtfully designed Ray Dolby Centre.”

Ray Dolby, who died in 2013 at the age of 80, came to Cambridge as a Marshall Scholar in 1957. He received his PhD from the Cavendish in 1961, and was a student and later a Fellow of Pembroke College.

In 1965, he founded Dolby Laboratories in London and invented the Dolby System, an analogue audio encoding system that forever improved the quality of recorded sound. He moved the company in 1976 to San Francisco, where it has been headquartered ever since.

The new Cavendish Laboratory will be its third home since its founding in 1874, and was first announced by the government in its 2015 Spending Review. It promised a £75 million investment in the Cavendish, which has been confirmed today, helping maintain Britain’s position at the forefront of physical sciences research. The funding will be delivered by the Engineering and Physical Sciences Research Council (EPSRC). Work on the new facility is expected to begin in 2019.

“This generous £85 million donation from the Ray Dolby estate along with the £75 million government has already pledged is a testament to the importance of this facility and the UK’s leadership in science,” said Science Minister Jo Johnson. “The UK is one of the most innovative countries in the world, and through our Industrial Strategy and additional £2.3 billion investment for research and development we are ensuring our world-class research base goes from strength to strength for years to come.”

“A successful nation invests in science, and this grant signals our intent to lead the world,” said Professor Philip Nelson, EPSRC's Chief Executive. “The facilities will be open to researchers across the country and encourage collaborative working between academics and institutions. Clearly Ray Dolby valued the university that nurtured his talents and, in making his bequest, has made a truly generous contribution to future generations.”

Inset image: Ray Dolby

Read more about how clinical researchers, physicists, engineers and social scientists are among those collaborating as part of the Cancer Research UK Early Detection Programme.

One of the fundamental ideas of quantum theory is that quantum objects can exist both as a wave and as a particle, and that they don’t exist as one or the other until they are measured. This is the premise that Erwin Schrödinger was illustrating with his famous thought experiment involving a dead-or-maybe-not-dead cat in a box.

“This premise, commonly referred to as the wave function, has been used more as a mathematical tool than a representation of actual quantum particles,” said David Arvidsson-Shukur, a PhD student at Cambridge’s Cavendish Laboratory, and the paper’s first author. “That’s why we took on the challenge of creating a way to track the secret movements of quantum particles.”

Any particle will always interact with its environment, ‘tagging’ it along the way. Arvidsson-Shukur, working with his co-authors Professor Crispin Barnes from the Cavendish Laboratory and Axel Gottfries, a PhD student from the Faculty of Economics, outlined a way for scientists to map these ‘tagging’ interactions without looking at them. The technique would be useful to scientists who make measurements at the end of an experiment but want to follow the movements of particles during the full experiment.

Some quantum scientists have suggested that information can be transmitted between two people – usually referred to as Alice and Bob – without any particles travelling between them. In a sense, Alice gets the message telepathically. This has been termed counterfactual communication because it goes against the accepted ‘fact’ that for information to be carried between sources, particles must move between them.

“To measure this phenomenon of counterfactual communication, we need a way to pin down where the particles between Alice and Bob are when we’re not looking,” said Arvidsson-Shukur. “Our ‘tagging’ method can do just that. Additionally, we can verify old predictions of quantum mechanics, for example that particles can exist in different locations at the same time.”

The founders of modern physics devised formulas to calculate the probabilities of different results from quantum experiments. However, they did not provide any explanations of what a quantum particle is doing when it’s not being observed. Earlier experiments have suggested that the particles might do non-classical things when not observed, like existing in two places at the same time. In their paper, the Cambridge researchers considered the fact that any particle travelling through space will interact with its surroundings. These interactions are what they call the ‘tagging’ of the particle. The interactions encode information in the particles that can then be decoded at the end of an experiment, when the particles are measured.

The researchers found that this information encoded in the particles is directly related to the wave function that Schrödinger postulated a century ago. Previously the wave function was thought of as an abstract computational tool to predict the outcomes of quantum experiments. “Our result suggests that the wave function is closely related to the actual state of particles,” said Arvidsson-Shukur. “So, we have been able to explore the ‘forbidden domain’ of quantum mechanics: pinning down the path of quantum particles when no one is observing them.”

Reference
D. R. M. Arvidsson-Shukur, C. H. W. Barnes, and A. N. O. Gottfries. ‘Evaluation of counterfactuality in counterfactual communication protocols’. Physical Review A (2017). DOI: 10.1103/PhysRevA.96.062316

As the global population increases, so too does energy demand. The threat of climate change means that there is an urgent need to find cleaner, renewable alternatives to fossil fuels that do not contribute extensive amounts of greenhouse gases with potentially devastating consequences on our ecosystem. Solar power is considered to be a particularly attractive source as on average the Earth receives around 10,000 times more energy from the sun in a given time than is required by human consumption.

In recent years, in addition to synthetic photovoltaic devices, biophotovoltaics (BPVs, also known as biological solar-cells) have emerged as an environmentally-friendly and low-cost approach to harvesting solar energy and converting it into electrical current. These solar cells utilise the photosynthetic properties of microorganisms such as algae to convert light into electric current that can be used to provide electricity.

During photosynthesis, algae produce electrons, some of which are exported outside the cell where they can provide electric current to power devices. To date, all the BPVs demonstrated have located charging (light harvesting and electron generation) and power delivery (transfer to the electrical circuit) in a single compartment; the electrons generate current as soon as they have been secreted.

In a new technique described in the journal Nature Energy, researchers from the departments of Biochemistry, Chemistry and Physics have collaborated to develop a two-chamber BPV system where the two core processes involved in the operation of a solar cell – generation of electrons and their conversion to power – are separated.

“Charging and power delivery often have conflicting requirements,” explains Kadi Liis Saar, of the Department of Chemistry. “For example, the charging unit needs to be exposed to sunlight to allow efficient charging, whereas the power delivery part does not require exposure to light but should be effective at converting the electrons to current with minimal losses.”

Building a two-chamber system allowed the researchers to design the two units independently and through this optimise the performance of the processes simultaneously.

“Separating out charging and power delivery meant we were able to enhance the performance of the power delivery unit through miniaturisation,” explains Professor Tuomas Knowles from the Department of Chemistry and the Cavendish Laboratory. “At miniature scales, fluids behave very differently, enabling us to design cells that are more efficient, with lower internal resistance and decreased electrical losses.”

The team used algae that had been genetically modified to carry mutations that enable the cells to minimise the amount of electric charge dissipated non-productively during photosynthesis. Together with the new design, this enabled the researchers to build a biophotovoltaic cell with a power density of 0.5 W/m2, five times that of their previous design. While this is still only around a tenth of the power density provided by conventional solar fuel cells, these new BPVs have several attractive features, they say.

"While conventional silicon-based solar cells are more efficient than algae-powered cells in the fraction of the sun’s energy they turn to electrical energy, there are attractive possibilities with other types of materials," says Professor Christopher Howe from the Department of Biochemistry. “In particular, because algae grow and divide naturally, systems based on them may require less energy investment and can be produced in a decentralised fashion."

Separating the energy generation and storage components has other advantages, too, say the researchers. The charge can be stored, rather than having to be used immediately – meaning that the charge could be generated during daylight and then used at night-time.

While algae-powered fuel cells are unlikely to generate enough electricity to power a grid system, they may be particularly useful in areas such as rural Africa, where sunlight is in abundance but there is no existing electric grid system. In addition, whereas semiconductor-based synthetic photovoltaics are usually produced in dedicated facilities away from where they are used, the production of BPVs could be carried out directly by the local community, say the researchers.

“This a big step forward in the search for alternative, greener fuels,” says Dr Paolo Bombelli, from the Department of Biochemistry. “We believe these developments will bring algal-based systems closer to practical implementation.”

The research was supported by the Leverhulme Trust, the Engineering and Physical Sciences Research Council and the European Research Council.

Reference
Saar, KL et al. Enhancing power density of biophotovoltaics by decoupling storage and power delivery. Nature Energy; 9 Jan 2018; DOI: 10.1038/s41560-017-0073-0

An international team led by Dr Renske Smit from the Kavli Institute of Cosmology at the University of Cambridge used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to open a new window onto the distant Universe, and have for the first time been able to identify normal star-forming galaxies at a very early stage in cosmic history with this telescope. The results are reported in the journal Nature, and will be presented at the 231^st meeting of the American Astronomical Society.

Light from distant objects takes time to reach Earth, so observing objects that are billions of light years away enables us to look back in time and directly observe the formation of the earliest galaxies. The Universe at that time, however, was filled with an obscuring ‘haze’ of neutral hydrogen gas, which makes it difficult to see the formation of the very first galaxies with optical telescopes.

Smit and her colleagues used ALMA to observe two small newborn galaxies, as they existed just 800 million years after the Big Bang. By analysing the spectral ‘fingerprint’ of the far-infrared light collected by ALMA, they were able to establish the distance to the galaxies and, for the first time, see the internal motion of the gas that fuelled their growth.

“Until ALMA, we’ve never been able to see the formation of galaxies in such detail, and we’ve never been able to measure the movement of gas in galaxies so early in the Universe’s history,” said co-author Dr Stefano Carniani, from Cambridge’s Cavendish Laboratory and Kavli Institute of Cosmology.

The researchers found that the gas in these newborn galaxies swirled and rotated in a whirlpool motion, similar to our own galaxy and other, more mature galaxies much later in the Universe’s history. Despite their relatively small size – about five times smaller than the Milky Way – these galaxies were forming stars at a higher rate than other young galaxies, but the researchers were surprised to discover that the galaxies were not as chaotic as expected.

“In the early Universe, gravity caused gas to flow rapidly into the galaxies, stirring them up and forming lots of new stars – violent supernova explosions from these stars also made the gas turbulent,” said Smit, who is a Rubicon Fellow at Cambridge, sponsored by the Netherlands Organisation for Scientific Research. “We expected that young galaxies would be dynamically ‘messy’, due to the havoc caused by exploding young stars, but these mini-galaxies show the ability to retain order and appear well regulated. Despite their small size, they are already rapidly growing to become one of the ‘adult’ galaxies like we live in today.”

The data from this project on small galaxies paves the way for larger studies of galaxies during the first billion years of cosmic time. The research was funded in part by the European Research Council and the UK Science and Technology Facilities Council (STFC).

Reference:
Renske Smit et al. ‘Rotation in [C II]-emitting gas in two galaxies at a redshift of 6.8.’ Nature (2018). DOI: 10.1038/nature24631