“There are two types of people when it comes to quantum,” joked Howard Dawber, deputy mayor of London for business and growth at a meeting at the Institute of Physics last night to celebrate the first anniversary of the London Quantum Cluster.

“There are those who understand quantum mechanics. There are those who don’t. And there are those who are in superposition of understanding and not understanding until they are observed.”

It was a light-hearted remark that matched the mood of what was essentially an evening of boosterism for quantum technology in London ahead of London Tech Week next week.

As chair of London and Partners – the growth agency for London – Dawber told the gathering of more than 100 “quantum influencers” that the organization was “100% behind the London Quantum Cluster”.

Founded in 2025 by University College London, King’s College London and Imperial College London, with support from the Mayor of London and the UK government, the cluster seeks to establish the capital as a powerhouse of quantum tech.

Georgia Siora from Warwick Economics and Development presented data to show that London is already doing well in the sector, being home to more than 160 quantum companies, with seven of the top 10 UK quantum firms based in the city. Small- and medium-sized quantum firms in the capital, she added, contribute an estimated £153m annually to the economy.

“Quantum and deep tech are at the heart of the capital’s 10-year growth plan,” added Janet Coyle, managing director of London and Partners.

Geraint Rees, vice-provost for research, innovation and global engagement at UCL, said his aim was “to make London the best place on the planet for serious quantum companies”. He pointed to UCL spin-out Quantum Motion, which has just won $160m of venture-capital funding, as an example of the kind of firm making a name in the city.

The evening ended with a panel debate chaired by Jess Wade from Imperial College London, featuring Maria Maragkou from Nu Quantum as well as Richard Murray, founder of ORCA Computing, who drew a distinction between universities being all about expanding the frontiers of knowledge, whereas for start-ups “the aim is to win”.

Also on the panel was physicist Alejandro Montblanch – head of quantum communication and networking at banking group HSBC – who made it clear that what he wanted to know was: “How can your quantum company help HSBC make more money?”

A welcome note of caution came from London-based venture-capital investor Eloisa Angeles, who pointed out that while the UK has a good track record of government-funded research, the UK  is weak at “follow through”, with the government not focused on procurement and not having the end customer of the research in sight.

• For more about the commercial impact of quantum economy, check out this feature by Philip Ball.

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Confine a liquid to a region a millimetre or less in size, and you’re in the weird world of “microfluidics” – where surface tension and capillary action dominate in ways we easily overlook from our macro-scale vantage point. Despite being a term that was coined only in 1992, the underlying phenomena have been with us for millennia, as Albert Folch argues in How the World Flows: Microfluidics From Raindrops to COVID Tests.

Folch, who is a professor of bioengineering at the University of Washington in the US, has spent his career developing microfluidic devices that exploit the peculiar properties of flows at this scale. In this book, he now steps back to admire the full scope and impact of microfluidics, revelling in droplets that form rainbows, deliver inhalable asthma medications, make up salad dressings and cosmetics, and print scaffolds of living tissue to aid patients’ healing.

I particularly enjoyed Folch’s ode to the Olmec – Indigenous people who lived in Central America from about 1200 BCE to 400 BCE. They would harvest latex from Panama rubber trees by tapping the bark and collecting the liquid drop by drop before the day’s heat caused the latex to coagulate and seal the cut. The Olmec even had their own version of vulcanization – the process that makes rubber elastic – using the juice of morning glory vines to process the sap into bouncy elastic balls, stretchy bands, shoe soles and raingear.

The Olmec spread their knowledge to neighbours as well. In fact, the name “Olmec” comes from the Aztec language and literally means “the rubber people”. Like the maple sugar industry – which gets its own historical treatment from Folch – the Olmecs’ latex harvest relied on a tree’s vascular system, made up of narrow 25 µm capillaries that carry liquids like water, sap, resin and latex to nourish and defend the tree. Although the Olmec civilization eventually declined, their technology and ingenuity lived on, impacting the entire world.

Folch walks readers not just through the physics and biology of these systems – capillary rise, photosynthesis, transpiration – but through their human impact, too. He includes wonders, such as natural rubber powering a Victorian-era craze that brought us tyres, inflatable boats, children’s dummies (pacifiers) and other objects. Folch also covers darker stuff, such as the British businessman Henry Wickham (1846–1928) who smuggled thousands of rubber tree seeds out of the Brazilian Amazon to establish plantations in Africa and Asia, where he could exploit cheaper labourers.

Another chapter begins in the mountains near Granada, Spain, where villagers are rebuilding acequias – open-air waterways originally built by the Moors in medieval times. For nearly 1000 years, acequias turned the arid slopes into terraced fruit gardens by diverting snowmelt toward agriculture and recharging the groundwater. Water seeps downward through the acequia’s dirt bottom, protecting it from evaporating in the hot Sun and feeding aquifers.

As Folch notes, aquifers contain nearly 30% of Earth’s freshwater – far more than is found in rivers and lakes, which make up less than 1% of the total. But in the US alone, industrial agriculture has been draining aquifers at rates as high as 60 cm per year, far exceeding the slow percolation of rainfall into these underground reservoirs.

In fact, aquifers take hundreds or thousands of years to recharge, which, Folch notes, means a depleted aquifer effectively ceases to exist for those of us living now. Without acequias and other dedicated efforts to replenish aquifer levels through microfluidic flow, today’s corn fields will soon turn to dust.

Candles to kidneys

How the World Flows charts the history of other unexpectedly microfluidic technologies too. Candles, for example, carry their fuel to the flame by capillary action along the wick. Then there’s paper, which soaks up ink through capillary action. Among more recent microfluidic inventions, Folch offers special laurels to the ballpoint pen, of which BIC alone has sold over 100 billion units since 1950.

Folch also takes care to introduce readers to many microfluidic medical devices, which might not be as widespread as ballpoint pens, but are perhaps more important. They range from dialysis machines that clean blood for failing kidneys, to COVID tests and continuous glucose monitors that let diabetics manage their blood glucose levels – a microfluidic technology that’s critical in my own home.

Folch describes the microfluidic devices that enable the Human Genome Project, as well as prototype instruments that could one day catch cancer cells through a simple blood screening. He also covers devices that could pick the perfect personalized drug cocktail for treating a patient’s tumour by studying their biopsied cells.

The most stunning microfluidic device Folch describes may be us.

But the most stunning microfluidic device Folch describes may be us. As he argues, we ourselves are microfluidic. From our lungs to our cardiovascular system, from our lymphatic system to our sweat glands, our bodies rely on flow through tiny vessels.

Our bodies make up for diffusion’s slow pace by operating in parallel. Like the many co-operating central-processing units in a supercomputer, our bodies absorb oxygen through 500 million micro-sized alveoli in our lungs. We hear through ears equipped by microfluidics to act as both microphones and accelerometers. Our kidneys clean some 200 litres of blood a day – sending two litres of urine to our bladders as they do – through massively parallelized filtration.

Throughout How the World Flows, Folch’s enthusiasm for his subject shines. His approach is that of a storyteller, rather than a scientist, and the book is all the better for it. Whether readers are microfluidics experts or not, they will walk away with new stories to tell. (Don’t skip the footnotes…)

Although Folch’s stories are wide-ranging and entertaining, he stumbles at times with the overarching narrative. Some transitions are rough, and it’s not always clear why he’s chosen to order the stories in the way they’re presented. Nevertheless, his book is a fun and highly readable introduction to microfluidics that’s sure to entertain lay readers and excite a new generation of microfluidic engineers.

• 2025 Oxford University Press 306pp £22.31hb £19.16ebook

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A PET radiotracer that can detect deep vein thrombosis (DVT) in the legs and clots that have travelled to the lungs has been chosen as the “Image of the Year” at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2026 annual meeting. Developed by Sangwon Han and colleagues at the Asan Medical Center, University of Ulsan College of Medicine, in Korea, the novel tracer enables whole‑body imaging of blood clots (thrombi) in the legs and lungs in a single scan.

A DVT is a blood clot that forms in a deep vein, usually in the legs. It’s a common condition, with an incidence of roughly half that of all cancers, and it can lead to serious complications. Clots can break off and travel to the lungs, which could cause a potentially life‑threatening pulmonary embolism (a blockage in the artery supplying blood to the lungs). Early detection of DVT is therefore critical for determining the most appropriate treatment for each patient.

Currently, the standard imaging method for diagnosing DVT is venous ultrasonography (VUS). But while this works well for detecting clots in the thigh-to-knee region, whole-leg VUS requires skilled operators and advanced machines, takes longer, and has lower diagnostic sensitivity in the calf. In addition, conventional imaging techniques such as VUS and CT rely on indirect structural changes rather than directly visualizing the clot.

Aiming to enable faster and more efficient DVT diagnosis, Han and his research team are studying fluorinated GP1 (¹⁸F-GP1) a novel thrombus-targeted PET tracer. The tracer selectively binds to specific receptors on activated platelets (the cell fragments that cause blood to clots), allowing direct visualization of active thrombus formation.

“In our Phase 1 study, ¹⁸F-GP1 PET/CT showed 100% detection rate in 20 patients with confirmed DVT or pulmonary embolism,” Han told the SNMMI delegates. “But that study was limited by its small sample size and an absence of negative groups so specificity could not be assessed at that time.”

So in this latest work, Han and his team performed a phase 2, non-randomized study investigating the ability of ¹⁸F-GP1 PET/CT to identify acute lower-extremity DVT in 46 symptomatic patients. This included 22 patients with proximal DVT and 24 with none or distal DVT, as diagnosed using VUS.

The researchers acquired chest-to-feet PET/CT scans approximately 2 h after intravenous administration of 250 MBq of the radiotracer. The images were assessed by three blinded nuclear medicine physicians from different institutions, who assigned focal ¹⁸F-GP1 uptake higher than background activity as positive for thrombosis. They classified proximal DVT as clots involving the iliac (pelvic), femoral (thigh) and popliteal veins (behind the knee), and distal DVT as clots confined to the calf veins.

“Our primary objective was to assess the sensitivity and specificity of qualitive ¹⁸F-GP1 PET/CT interpretation for proximal DVT,” Han explained. “Secondary objectives included assessing the agreement between PET/CT and VUS for distal DVT, inter-reader reproducibility, exploring the detection of pulmonary embolism and assessing safety.”

When evaluated against VUS as a reference standard, ¹⁸F-GP1 PET/CT exhibited high diagnostic accuracy for detecting clots, demonstrating a sensitivity of 95% and a specificity of 92% for proximal DVT. “For distal DVT, both positive and negative agreement between PET/CT and VUS were strong,” added Han. “Inter-reader agreement was also excellent.”

The scans also identified concomitant pulmonary emboli in some patients, as confirmed by CT pulmonary angiography, illustrating the advantage of simultaneously assessing DVT and pulmonary embolism in a single scan. The researchers noted that the radiotracer was well tolerated, with no drug-related adverse events observed.

Speaking in the plenary session when his award was announced, Han shared a “striking image” recorded using ¹⁸F-GP1 PET/CT, which showed extensive blood clots, not only in the leg and lungs, but also in many unusual sites, including cranial and spinal vessels, cardiac valves, and vessels in the pelvic region. “This image clearly shows the remarkability ability of fluorinated GP1 to visualize thrombi throughout the body,” he explained.

“We believe this represents an important step towards thrombus-specific imaging,” Han concluded. “The potential of GP1 PET can expand beyond DVTs to many other thrombotic diseases such as embolic stroke or other cardiovascular diseases.”

The SNMMI Image of the Year is the society’s highest award, and the most anticipated, given out in recognition of an image that’s truly cutting-edge and representative of the future of nuclear medicine. This year’s winning image was chosen from nearly 1500 abstracts submitted for the meeting.

“It is truly a great honour to receive the Image of the Year award,” said Han.

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Rectification is the process of turning alternating current (AC) signals into direct current (DC), and it underpins technologies such as wireless power transfer, photodetection, terahertz sensing, and energy harvesting. To generate a one-directional current, a material normally needs a built-in directional preference for electron motion. This preference usually arises from broken inversion symmetry, meaning that the material is not identical under spatial inversion. For example, graphene has inversion symmetry, while materials with inequivalent sublattices, intrinsic electric dipoles, surfaces, or interfaces naturally break it. When inversion symmetry is broken, electrons can respond differently to opposite directions of an applied light field, allowing oscillating optical fields to generate a DC current.

In this work, the researchers show that this rule has an important exception. Even centrosymmetric bulk materials can rectify light through third-order nonlinear optical effects. Linear optical responses scale with the applied light field. Second-order responses depend on the square of the electric field and can mix frequencies or generate harmonics, but they are usually forbidden in centrosymmetric bulk materials. Third-order responses, however, are symmetry allowed and can generate DC photocurrents even when inversion symmetry is present. These currents are controlled by the shape of the Fermi surface, disorder, and the geometry of electronic bands. This means that materials once considered unsuitable for bulk optical rectification, including common metals, doped systems, and two-dimensional materials, can be engineered to convert oscillating light into DC electrical signals.

This research expands the material platform for optical rectification. Instead of relying only on noncentrosymmetric crystals, it shows that common centrosymmetric materials can also be used for light-to-DC conversion through third-order nonlinear response. This opens a route to energy-efficient photodetectors, terahertz technologies, and future energy-harvesting devices based on materials such as graphene.

Do you want to learn more about this topic?

Balancing selectivity and permeability in nanofluidic membranes for osmotic power generation Han Qian et al. (2025)

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In condensed matter physics, driving a material with an external stimulus can push it into new nonequilibrium states that reveal hidden properties or create entirely new, potentially useful behaviours. These stimuli can include optical driving, where strong oscillating light is applied to the material, or periodic forcing, which refers to any repetitive push such as acoustic waves, modulated electric fields, or oscillating magnetic fields. 

In this work, the researchers wanted to understand how shining bright, oscillating light on a material can make it behave in unexpected ways, sometimes even resembling a superconductor. They used a theoretical model to study what happens when the system is periodically driven, allowed to exchange energy with a heat bath, and coupled to electromagnetic fields. When the drive is strong enough, the system can spontaneously organise into different kinds of ordered states: uniform order, spatially patterned order, or time oscillating order. 

Ordered phases can repel magnetic fields in the same way a superconductor does, through the Meissner effect, where the electromagnetic field behaves as if the photon has gained an effective mass and therefore cannot propagate inside the material. In some driven phases, however, not all of the magnetic field is expelled: part of it enters the material but only as a standing wave, forming a hybrid light-matter excitation known as a Meissner polariton. Additionally, strong fluctuations near the onset of ordering can make the material’s optical conductivity appear superconducting, causing experiments to detect superconducting like signals even when no true superconducting phase is present, helping explain why light‑driven systems sometimes show ambiguous signs of superconductivity. 

Overall, the researchers developed a unified theoretical picture showing how periodic driving can create or mimic superconducting behaviour, including predicting a new hybrid light-matter mode (the Meissner polariton), offering insight into puzzling experimental results in light driven materials.

Do you want to learn more about this topic?

Laser-induced magnetization dynamics and reversal in ferrimagnetic alloys by Andrei Kirilyuk, Alexey V Kimel and Theo Rasing (2013)

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Experimental attosecond science is built around the ability to generate and control light flashes lasting billionths of a billionth of a second. Such extreme pulses can be created through high harmonic generation (HHG), where an intense laser field drives electrons out of atoms or solids and then forces them back, releasing bursts of extreme ultraviolet radiation. Techniques like this have transformed our ability to observe electron motion on its natural timescale.

To extract information from such ultrafast processes, physicists often rely on attosecond interferometry. By combining a strong laser field with a weaker second colour, different electron trajectories are made to interfere, imprinting timing and phase information onto the emitted harmonics. Over recent years, these schemes have become standard tools for attosecond metrology and spectroscopy.

In a recent paper published in Reports on Progress in Physics, Javier Rivera Dean et al, revisited this idea from a quantum optical perspective. Treating both the driving fields and the emitted harmonics as quantum rather than classical objects, they analysed how attosecond interferometric control influences the photon statistics, correlations and phase space structure of the generated light. Their calculations show that even when harmonic radiation appears classical in its average properties, its underlying quantum state can carry rich and measurable structure.

The study also explores how interferometric phase control can be repurposed as a practical probe of quantum optical features in spectral regions where standard techniques, such as homodyne detection, are unavailable. This represents a new approach for measuring phase-space distributions through tomographic reconstruction: attosecond quantum tomography.

By combining quantum optics with common attosecond techniques, the work shows how ultrafast science is increasingly becoming a platform not just for watching electrons move, but also for studying light itself at the shortest timescales accessible in the laboratory.

Do you want to learn more about this topic?

The physics of attosecond light pulses – IOPscience by P. Agostini and L. F. DiMauro (2004)

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