Single atom transistor gets precise position on chip

The basic unit of matter could become the basic unit of computing. A lone atom of phosphorus embedded in a sheet of silicon has been made to act as a transistor.

It is not the first single-atom transistor, but it can be much more precisely positioned than its predecessors, potentially making it a lot more useful.

“It’s an absolutely fantastic piece of engineering,” says physicist Bruce Kane at the University of Maryland, who was not involved in the work.

Elaborate production methods would initially prevent single-atom phosphorus transistors from being a worthwhile addition to traditional computers, but they may be necessary one day. The devices could also find an application in futuristic, super-speedy quantum computers.

A transistor is essentially a lump of conducting material sitting between two electrodes that acts as a switch. A pulse of voltage is supplied by a further electrode,”opening” the switch and allowing current to flow through the transistor.

Wiggling atom

Combining transistors on a chip produces logic circuits that can carry out computations. A goal shared by computer chip makers is to keep shrinking the transistor: squeeze ever more onto a single chip and you increase its computational power.

To dictate the exact position of their single atom, Michelle Simmons at the University of New South Wales, Australia, and colleagues started by covering a silicon sheet with a layer of hydrogen. Then they used the tip of a scanning tunnelling microscope to remove hydrogen atoms according to a precise pattern. They exposed two perpendicular pairs of exposed silicon strips plus a tiny rectangle made of just six silicon atoms that sat at the junction between these strips (see diagram, right).

Adding phosphine gas (PH₃) and heating caused phosphorus atoms, which are conducting, to bind to these exposed areas of silicon. In the case of the rectangle only one atom inserted itself into the silicon network.

The result was four phosphorus electrodes and a single phosphorus atom.

Boutique operation

One pair of electrodes was separated by a 108-nanometre gap. Creating a voltage between them allowed current to flow between the two perpendicular electrodes – separated from each other by just 20 nanometres, through the single phosphorus atom, which acted as a transistor.

Kane points out that the atomic transistor works at temperatures below 1 kelvin and that fabrication is difficult. “It’s a very slow, boutique operation to make one of these,” he says.

Simmons agrees, but counters that the traditional computer makers may be forced to adopt this technology if they want to make ever smaller chips. “This is one of the only techniques that allows you to make single atom devices,” she says.

Physicist Jeremy Levy of the University of Pittsburgh in Pennsylvania reckons the future of single atom transistors lies in quantum computers. The spin of the electrons in isolated phosphorus atoms could serve as qubits, the quantum equivalent of the bits in today’s computers. Controlling the interaction between qubits requires knowing the exact location of each one. Now that the location of individual atoms can be controlled, the next challenge is to link two of these transistors, Levy says.

Journal reference: Nature Nanotechnology, DOI: 10.1038/nnano.2012.21

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How fresco-wrecking salty towers build themselves

CORAL-like formations of salt sometimes sprout up on walls, damaging frescoes and other artwork, and now researchers know why.
Experiments and simulations by Marc Prat at the University of Toulouse in France and colleagues show how salty water evaporating from the pores in these materials leaves behind patches of salt crystals that grow into towers rather than a uniform film.
The towers are themselves porous and suck in more salty water. As they grow, water evaporating from their sides inhibits evaporation from surrounding areas, preventing crystal growth around the towers (Physical Review Letters, DOI: 10.1103/physrevlett.108.054502).
The work suggests that maintaining the right distribution of humidity over delicate frescoes may prevent such structures from forming.

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Uncharted waters: Probing aquifers to head off war

 

The water's edge (Image: George Steinmetz/Corbis)

Nearly all our fresh water comes from obscure underground deposits – now satellites and radioactive isotopes are telling us how much we have to go round

DEEP beneath the eastern Sahara, the Nubian Sandstone aquifer was in trouble. By the early 2000s, the aquifer - one of the largest and oldest groundwater deposits in the world, which supplies Libya, Egypt, Chad and Sudan - was emptying fast. Egypt was tapping the aquifer to feed its growing desert cities far from the Nile. Libya, whose only other water source is the salty Mediterranean, was drawing water off by way of an underground network of pipes and aqueducts known as the Great Man-Made River, which Libyans describe as the eighth wonder of the world.

Soon the Sahara's oases began to dry up, causing water shortages for nomadic groups and wildlife. But no one could agree on who was to blame. The ancient aquifer system was just too complicated: it was impossible to pinpoint who was taking too much water, or even estimate when it would run out.

Because none of the countries trusted the others to provide an unbiased analysis, they couldn't agree on what steps, if any, to take to protect the aquifer. Mistrust and a lack of cooperation threatened to spiral into something worse.

This conflict exposed an ordinary truth that had somehow been forgotten: most of the world's drinking water is hidden underground, and we don't have a clue what's happening to it. But as global populations grow and climate change kicks in, one thing is certain: we can no longer count on the water to be where we expect to find it. Our groundwater is dissipating into the ocean, being consumed at record rates and being irreversibly contaminated; even as claims to what remains become increasingly contentious. It won't be long before shortages cause widespread droughts and the first water war begins.

How can we stop this? The first step is knowing where the water is. Conventional maps are no longer enough when you're dealing with an invisible, moving target. But there is hope. Impressive new physics and engineering tools are beginning to yield the first clear pictures of the world's hidden water. These have already revealed some unexpected good news, but their real promise is in the possibility of a world map of a resource more precious than oil.

See graphic: "Mapping the world's unseen water"

Although it comprises 97 per cent of the world's accessible fresh water - the UN Environment Programme's latest estimate - we have never really bothered to get a clear picture of the water beneath our feet. Most hydrologists prefer to study the water on the Earth's surface. "Certainly groundwater has suffered from an 'out of sight, out of mind' problem," says Peter Gleick, a hydroclimatologist who runs the Pacific Institute, an independent think-tank based in Oakland, California.

Most people would be surprised to hear that. After all, it's been easy enough to exploit the water hidden in aquifers. These underground stores are vast; the 40,000 cubic kilometres of water in the Guarani aquifer in South America, for example, far exceeds what's in all five of North America's Great Lakes. But this water isn't held in a vast underground lake. Instead, it moves, often slowly, through complex layers of permeable rock, sand and other geology. And unlike a lake, how useful it is depends not only on how much water it contains, but on how quickly it is refilled by rainwater or snowmelt.

Parched landscapes

Plenty of maps show where the world's aquifers are located, but they make no mention of how much water they contain, how fast the water levels are changing, or even whether the water is safe to drink. As the world's population increases, so too does demand, but that isn't the only cause for concern. Climate change is gradually redistributing the world's water. As the Earth warms, precipitation is shifting from the mid-latitudes to the low and high latitudes. Wet areas are becoming wetter and dry areas drier, which may account for the record-breaking droughts in east Africa and Texas last year. Less rainfall in these mid-latitudes means less new water to refill the aquifers that are being depleted the fastest, and that means more aquifers will become like the Nubian - a precarious source in a parched landscape.

To figure out how much water we can sustainably take from such a fragile system, we need to know two things: how old the water is, and how quickly it is being replenished.

Until recently, the only way to get that kind of data was with costly and time-consuming borehole studies. These involve digging lots of narrow wells in order to monitor the speed and direction of the water flow, and then using that data to construct a model of the aquifer.

In the case of the Nubian aquifer, however, such a study was out of the question. For one thing, it would have been too expensive, and many of the drilling sites would be in remote desert. More than anything, however, such intensive studies require a political appetite to set them in motion, and since previous borehole studies had met with scepticism, a dense network of boreholes across four countries would be hard to justify.

The solution came from an unexpected corner: the International Atomic Energy Agency (IAEA). Alongside its work with nuclear energy and weapons, the organisation also uses isotopes for water analysis. Pradeep Aggarwal, who runs the IAEA's isotope hydrology division, had been using isotopes to test surface water for decades, and he saw an opportunity to help the Nubian aquifer. In 2006, Aggarwal and Zheng-Tian Lu, a physicist at Argonne National Laboratory in Illinois, launched a major project with The UN Development Programme and other agencies to create a comprehensive map of the aquifer. Not only is isotope testing much cheaper, because it only requires taking a few water samples from existing wells, but this handful of samples can reveal the state of the whole aquifer. "Measuring isotopes in one location can tell you what is happening tens, and even hundreds of kilometres away," says Aggarwal.

First, they needed to work out how old the aquifer was, and for that, the team turned to carbon-14. Just like ancient artefacts, water can be dated using this radioactive isotope. Above ground, water absorbs some of the gases in the atmosphere, including carbon dioxide, causing it to take on the atmosphere's signature cocktail of isotopes. When the water later disappears into an aquifer, it takes this unique signature with it. As time passes, the carbon-14 undergoes radioactive decay. The amount that remains in a sample of water can reveal the water's age.

It turned out that there was practically no carbon-14 left in their samples. That meant the water was extremely old.

The finding squared with previous carbon-14 studies, which had suggested the Nubian aquifer was 40,000 years old. But Aggarwal realised this figure was close to the isotope's 50,000-year dating limit, raising doubts about its accuracy. So he turned to krypton-81, a rare isotope that researchers have only recently learned how to trap and count, which can accurately determine the age of water back to 2 million years. Lu discovered that indeed, the carbon-14 studies had been way off: a good portion of the water in the Nubian aquifer is closer to a million years old (Geophysical Research Letters, vol 31, p L05503).

But simply knowing the water's age wasn't enough. To get a complete picture of the aquifer, Aggarwal needed to understand whether any part of it was being refilled with new water.

The team did this by looking at two isotopes of the atoms that make up the water molecule - deuterium and oxygen-18. Every drop of water has a telltale ratio of these two isotopes, which offers clues to the climate at the water's source. Both of these heavy isotopes decreases in cooler climates. Therefore, a sample with a lower concentration of oxygen-18 and deuterium would suggest that the last time new water was being deposited, the climate around the Nubian aquifer was cooler.

Sure enough, the deuterium and oxygen-18 in the samples confirmed that no new water had been deposited there during modern times. The aquifer contained only "fossil water" that had been trapped underground long ago. In other words, this aquifer was not being refilled and would one day run dry.

This was bad news. However, thanks to the isotope studies, Aggarwal was also able to calculate how much total water remained in the aquifer. It may be old, but it turned out that enough fossil water remains in the aquifer to last at least several centuries. Not only that, but the water flows so slowly that one country's pumping doesn't immediately affect another. "So Chad doesn't have to worry about Libya stealing its water," says Aggarwal.

In the wake of the IAEA's conclusions, the countries that rely on the Nubian aquifer finally agreed that they need to work together to protect it, which broke decade-long tensions. "We were able to build a model that all four countries accepted as a reliable simulation," Aggarwal says. The IAEA has nearly completed a world atlas that extends the work they did on the Nubian Sandstone aquifer, and Aggarwal ultimately hopes to map the world's groundwater according to age and recharge rate (see map).

But none of that will help the local oases, which are still drying up - along with a lake in Libya. That's because political tensions are not the only problem in the global water picture.

Even when an aquifer supplies only a single country, it's not always clear who is using the water or for what purpose. "We've been overpumping groundwater and we've known about it for decades," says Gleick. "But policies still can't get a handle on it." A complete account of groundwater use would require nations and industries to measure their indirect as well as real water use, which few do.

Now Jay Famiglietti and his team at the University of California at Irvine have found a way around this: tracking real-time changes to the world's groundwater from space. To do this they rely on data from NASA's Gravity Recovery and Climate Experiment (GRACE), which measures variations in Earth's gravitational field. GRACE uses two satellites orbiting about 220 kilometres apart. When the first satellite flies over a spot where gravity becomes stronger - a mountain, say, or massive aquifer - it is temporarily drawn closer to the Earth and away from the trailing satellite. By measuring the changes in the distance between the two satellites, they can create a detailed map of the Earth's gravitational field.

Famiglietti's group has taken this idea one step further. They have been able to correlate the satellites' gravity data with significant changes to underground aquifers caused by wet and dry seasons, long-term droughts and water extraction for mining and agriculture.

A radical new map

The team raised eyebrows in 2011 when they published a controversial study showing that a major aquifer beneath California's Central Valley was being depleted much faster than anticipated, due to water-thirsty lettuce farms (Geophysical Research Letters, vol 38, p L03403). Last year, Famiglietti told New Scientist that if the unregulated nature of the farming continued, the aquifer would be depleted by 2100.

Like Aggarwal, Famiglietti is now putting together a global map based on the information he gathered from GRACE. His findings are sobering. We are depleting every one of the world's major mid-latitude aquifers. As in California, the main culprit is agriculture, which uses massive amounts of water.

Agriculture is not the only industry taking a toll. In Australia, Famiglietti and his team says their map may indicate serious depletion of the groundwater in areas where mining takes place. "Yes, we know that mining is intensive. But has anyone ever shown them a map like this? No," he says. Changes in rainfall are also playing a role, though his team has yet to worked out precisely how much. But the water is moving, that much is certain. "When you see this big-ass red spot that covers a fifth or a sixth of the continent, it raises your eyebrows," he says.

GRACE can only track changes in aquifers with areas greater than 150,000 square kilometres. But even so, multiplying GRACE's water output data with the isotope studies' age calculations gives us a rough estimate of the total amount of water in a given aquifer. Do this for all aquifers, Famiglietti says, and we can get the first good picture of how much fresh water is stored underground and where it's going. What's more, this information could allow us to predict water shortages, possibly with enough warning for countries to mitigate their effects or even stave them off altogether.

Such projects are still in their infancy. One is being carried out by Famiglietti's former graduate student, Matt Rodell, who analyses US water data at NASA. In December, Rodell's group showed that the record-breaking drought in Texas - the driest 12-month period on record since the 1890s - reduced groundwater levels in much of the state to their lowest in 60 years. Their prediction that recharging the aquifer would take months was enough to motivate the state to develop more effective water conservation methods.

In some cases, for example, it's possible to counter droughts by artificially recharging an aquifer with purified wastewater to keep it filled. California has done this for decades, and Egypt is experimenting with doing the same in a shallow, young part of the Nubian aquifer by feeding it with water from the Nile.

Develop a thorough enough understanding of the world's water, and we might even be in for a few pleasant surprises. Though finding large amounts of new fresh water is not on the cards, it is possible that such a map could unearth small supplies. On the parched Santa Elena peninsula in Ecuador, for example, residents had only three wells that gave water sporadically. But after an IAEA isotope investigation in 2009, residents dug four sustainable wells that now give water 24 hours a day. And in Bangladesh, where arsenic in the water was poisoning millions of people, isotope studies identified previously unknown aquifers whose waters were safe.

Maps alone won't refill the oases in the desert, but they are key to making sure everyone has enough. Ultimately, preventing water conflicts will be less about absolute amounts of water than about the fair distribution of what's there. The first step is knowing where it's going and who's taking it. Even amid all the bad news, there are bright spots: As more countries - from Canada to India to Australia - wake up to the problem and begin to track their hidden water, the tools to help them do so keep getting better.

Chelsea Wald is a freelance writer based in Vienna, Austria

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The internet shows the messy truth about knowledge

 

Our old idea of knowledge shaped itself around the strengths and limitations of its old medium, paper (Image: Fahid Chowdhury/Flickr/Getty Images)

Books and formal papers make knowledge look finite, knowable. By embracing the unfinished, unfinishable forms of the web we are truer to the spirit of enquiry – and to the world we live in

IN RECENT years, controversies over issues ranging from the possibility of faster-than-light neutrinos to the wisdom of routine screening for prostate cancer have increasingly raged outside the boundaries of peer-reviewed journals, and involved experts, know-nothings and everyone in between. The resulting messiness is not the opposite of knowledge. In the internet age it is what knowledge looks like, and it is something to regret for a moment, but then embrace and celebrate. Knowledge is fast reshaping itself around its new, networked medium - thereby becoming closer to what it truly was all along.

Our old idea of knowledge shaped itself around the strengths and limitations of its old medium, paper. We all understand those strengths: paper is cheap, displays text and graphics, lasts a lot longer than hard drives, and no technology is needed to make it work. But there's a price: paper doesn't scale or link, which has made knowledge and science both what they are and less than they could be.

Paper fails to scale in two directions. First, there are limits on what can be published: if it is not considered important enough, even good science is rejected. That is a reasonable response to the cost of journal printing and shelf space but it is far from the ideal of science, where all data and all hypotheses are welcome. With such limitations, regimes emerge to dole out the scarce resource. Second, printed articles rarely contain all the data on which their conclusions are based, and literature reviews are kept to a reasonable length - reasonable being dictated by the economics of atoms.

The other limitation has an arguably greater effect: printed matter does not link. Each book is its own thing. The references to other books don't work, no matter how hard you click them. That means the author has to cram everything the reader needs into one volume, summarising references to other books in a single paragraph, and pulling sentences out of their rich context.

Printed books are also disconnected from the discussions that appropriate them into the culture - and that correct them. Authors must anticipate objections because once published, books cannot be altered. In the Age of Paper, knowledge looks like that which is settled, or settled enough to be committed to paper.

These limitations led to the typical rhythm of scientific discourse. Do your research. When you're as sure of it as you're going to be, make it public. Only then is it officially yours. If someone publishes before you, you lose. And once it is public, it becomes hard - and often embarrassing - to change even a word.

Science's new medium overcomes both limitations. We have scarcely plumbed its capacity, and it is so hyperlinked that if digital content is not linked, it is essentially unpublished. This fundamentally changes the understanding of the nature of knowledge and science prevailing in the west for the past 2500 years: to know X was to know its essence, its place in the rational order. That order consisted of a set of coordinated definitions based on essential differences and similarities. That's one reason Charles Darwin spent seven years discovering whether barnacles were molluscs, as Linnaeus said, or crustaceans. The result was a two-volume work to establish a single fact: they are crustaceans.

These days we don't care nearly as much, in part because we recognise that how we classify things depends on our interests. Studying the evolution of marine creatures? Classify them based on their genetic history. Studying how to keep hulls smooth? Then lump barnacles with rust. The internet has decisively moved us from belief in a knowledge of universal essences because it has made plain two facts: we don't agree, and we can't let that stop us.

For example, at the online Encyclopedia of Life (EOL), you can look up an organism by any name you want, and obtain information about it within any of the taxonomies it supports. So two scientists who disagree can collaborate because they know they are both talking about the creature on the same page of the EOL. This is an example of "namespaces"; domains that bestow a set of unique identifiers on their objects. These names can be mapped so we can work together without having to agree. The result is a sloppy mess with names and categorisations overlapping unevenly. But the different schemes add information and meaning: so long as we can map them, we are better off not waiting for resolution.

We see the same approach with another promising development: the rise of "big data". Organisations are releasing gigantic clouds of data for public access. Since these are too voluminous for cranial processing, the data is increasingly released in the linked data format recommended by Tim Berners-Lee. In this format, data consists of "triples": subject, object and a relationship connecting them.

This might look like a further atomisation of facts and information, but it is the opposite since each element of a triple should ideally consist of a link pointing to some spot on the web. For example, in the triple "barnacles have shells", the word "barnacle" might link to an EOL entry, "have" to a site that explains how creatures can have components, while "shell" might point to the relevant Wikipedia entry. This technique helps computers see that the triple "Cirripedia are crustaceans" refers to the same thing as triples calling them "barnacles". Linked data are facts literally consisting of links. The resulting tangle of pointers is quite unlike our old view of facts as well-defined building blocks.

And these clouds of data are being released without being thoroughly vetted. For example, the US government website, Data.gov, says that the data it has gathered from federal agencies is raw. We might prefer tidy, vetted data, but that doesn't scale; we do better to have lots of data, even if it's not perfectly structured or completely reliable. Messiness is the price of scaling.

Further, rather than working in private and publishing to a select group, we are finding tremendous value in posting early on non-peer-reviewed sites, and letting everyone chime in. We saw this when the scientists who discovered what might be faster-than-light neutrinos posted their work at arxiv.org, the pre-print site. The discussion sprawled across the internet, with amateurs and professionals weighing in, with kind-hearted experts explaining it to lay people, with insightful and pointless ideas stirred together - and all without prior peer review and outside the standard journals.

The result was that if you wanted to see where the knowledge about neutrinos "lived", you wouldn't go to the library or online versions of the standard journals. The knowledge lived in the loose web of discussion and debate. All this happened faster, wider and deeper than if science had stayed in its paper comfort zone. Even after the question is settled, the knowledge will live not in the final article but in that web of discussion, debate, elucidation and disagreement. It's messy, but messiness is how you scale knowledge.

Knowledge has inherited many other of the web's properties. It is now linked across all boundaries, it is unsettled, it never comes fully to rest or agreement, and we can see that it is bigger than any of us could ever traverse. But doesn't that make internet-based knowledge and science more like the very human world into which we have been thrown?

David Weinberger is a senior researcher at Harvard University's Berkman Center for the Internet and Society. This essay is based on his new book, Too Big to Know (Basic Books)

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Latest US drug shortage hits children with leukaemia

Stocks of a vital cancer drug are running low in the US, which could affect children with leukaemia within weeks.

The US Food and Drug Administration says a number of drug manufacturers are flagging up shortages in methotrexate – which slows the growth of white blood cells in acute lymphoblastic leukaemia, a cancer that typically affects young children.

Manufacturing delays and unexpectedly high levels of demand are blamed for the shortfall, together with the voluntary closure of Ben Venue Laboratories, one of the nation's largest suppliers of the drug.

Oncologists are concerned supplies could run out in some areas within weeks. Reports suggest that the FDA is seeking a foreign supplier to provide emergency imports until domestic ones can meet demand.

Legislation designed to give an early warning of drug shortages was passed to a government committee last summer.

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The insect survival guide

Rowan Hooper, news editor

INSECTS make up 75 per cent of all known animal species. That's about 900,000 of them, with at least 3 million yet to be identified. It's a vast subject area, but veteran entomologist Gilbert Waldbauer brings it to life by exploring insect warfare - the strategies these creatures employ to protect themselves from predators.

There are times when How Not to Be Eaten feels like one long list of examples, but on the whole this is a rich and detailed book that roams across time and space. Waldbauer cites the work of Victorian naturalists alongside recent studies - examples include the way tiger moths generate ultrasonic sounds to repel hunting bats just as butterflies display don't-eat-me colours.

The book describes insects from all over the world, interspersed with anecdotes from Waldbauer's own field trips. Some of my favourites include the spider in South America that catches moths by swinging a bolus of sticky glue on the end of a silk thread - humans are the only other species to use a similar weapon. Then there are the burrowing owls in southern Florida that hunt beetles by scattering lumps of cattle dung as bait. Or the Burnet moth, common in Europe, which secretes deadly hydrogen cyanide stored in its exoskeleton.

Chemical warfare, camouflage, ambush. Sun Tzu could have learned a lot from insects when he wrote The Art of War.

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Eat rich or die trying: just desserts

Helen Thomson, biomedical news editor

I can’t quite describe what’s in my mouth. It’s sort of savoury, but with a hint of sour, a bit oat-like too. It’s overwhelmingly delicious. Luckily for me, this is the first of six puddings that not only use science to boost my sensations, but are also designed to reveal to me my true love and even how many years it will be until I marry.

I’m at Eat Rich or Die Trying, a quarterly dining club dedicated to desserts, located at the Kemistry Gallery in Shoreditch, London. Given it’s just around Valentine’s Day, they’ve pointed cupid’s arrow into the kitchen to produce a sugary feast that promises to guide diners from love at first sight to romance’s bitter end.

And that’s why words are failing me. My first course has been created by Blanche and Shock, a design studio and catering company in London who describe their dessert “as tingly and difficult to pin down as the first inkling of love.” By incorporating an umami element into the concoction – in this case using porcini crème fraiche – these clever chefs designed a puzzling plate that is disconcertingly delicious but difficult to work out why. Umami is the taste of glutamates and nucleotides that is now widely accepted as the fifth sensation alongside bitter, sweet, sour and salty. Together with a spiced cox apple, tea bread and honey, the mixture creates a blend of flavours that everyone around my table agrees cleverly mirrors the experience of being attracted to someone, though none of us quite knows why.

As your granny will tell you, any decent relationship must next involve “courtship”. Andrew Stellitano from food design company Astarism is fascinated by the evolution of the love story. Tonight, for the second course, he incorporates a selection of ingredients prized for their power to stimulate or attract love. Central to the plate is a rice milk ice cream. Experiments in rats have shown that a chemical found in rice called cadmium mimics the effect of oestrogen in women, and females with high levels of oestrogen are perceived as more healthy, feminine and attractive, so perhaps he’s onto something here.

Stellitano’s dessert is garnished with a tuile, which I am encouraged to shatter and count the pieces – apparently to reveal how many years I will wait until marriage. Delicately, I tap my tuile. It cracks into four. I glance to my right, just in time to see my dining partner Sarah smash her spoon into the dessert, her tuile splitting into a thousand tiny pieces. Some fly off her plate and scatter across the tablecloth, others land on the floor. Snorts of laughter erupt around the table.

One after another, more love-themed desserts are placed in front of us. A soot and salt drop scone by ‘The Curious Confectioner’ is a highlight. With the prospect of six puddings on the menu, I’m pleased to hear that its ingredients include activated charcoal, a highly absorbent element thought to help aid digestion.

“Is it weird that I’m slightly nervous?” asks Sarah as we move onto the fourth desert, called ”The Marriage”, before tucking into the fifth, which supposedly represents the bitter sufferings of love. While spiced chocolate ganache does give a bitter twist to the meal, chocolate has another connection with love and attraction. Early in a relationship dopamine-rich brain regions associated with motivation and reward become highly active, and supposedly the more intense the relationship the greater the activity. The same regions are active when a person enjoys chocolate, according to Helen Fisher, an anthropologist from Rutgers University in New Jersey. It appears tonight’s molecular sorcerers have at last hit upon a dessert that really might entice feelings of love and attraction. It’s certainly very tasty.

Like all good fairy tales, my dessert reverie ends as the clock strikes midnight. The final treat is cookie dough cooked three ways, including sous-vide, in which the food is placed in a vacuum bag and heated gently in water. The chef says the idea is that the dough is cooked but retains much of the experience of eating dough from the bowl. Unfortunately the overwhelming flavour of aniseed and the resemblance of scrambled egg on my plate were just too much for my stomach to handle this late into the night.

For someone with a sweet tooth, love of science and food, and an overactive imagination, the majority of this evening was a delight. It’s just a shame this love story, like many in the past, left me tired, emotionally drained and with a bitter taste in my mouth.

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