Tracking global migration has long been hampered by poor, outdated data. Now researchers have harnessed social media data to create a near real-time map of international movement.
In this week's episode of Space Minds, Bill Nye, CEO of the Planetary Society sits down with host David Ariosto. The conversation starts with Bill's journey but quickly pivots to the proposed science budget cuts at NASA.
A key player in the European DeepTech market and a leading Polish space technology company, Creotech Instruments S.A., has signed the largest contract with the European Space Agency (ESA) to […]
The Texas Space Commission has awarded more than $26 million to five companies in the latest round of awards designed to stimulate the state’s space industry.
GPS is not only a cornerstone to our military superiority, it is foundational to our national and global economic stability. In fact, analysts warn that GPS outages could cost our […]
Workers who recently lost their jobs at the National Institute for Occupational Safety say they’re concerned that there’s no plan for managing biological samples tied to research projects.
Astronomers using the James Webb Space Telescope confirmed that the planet K2-18b has traces of dimethyl sulfide, a potential biosignature of marine microorganisms.
This podcast features Alonso Gutierrez, who is chief of medical physics at the Miami Cancer Institute in the US. In a wide-ranging conversation with Physics World’s Tami Freeman, Gutierrez talks about his experience using Elekta’s Leksell Gamma Knife for radiosurgery in a busy radiotherapy department.
Learn how the boundaries of the magma chamber beneath Yellowstone have been located, and discover how these boundaries hint at the volcano’s future behavior.
A concept from quantum information theory appears to explain at least some of the peculiar behaviour of so-called “strange” metals. The new approach, which was developed by physicists at Rice University in the US, attributes the unusually poor electrical conductivity of these metals to an increase in the quantum entanglement of their electrons. The team say the approach could advance our understanding of certain high-temperature superconductors and other correlated quantum structures.
While electrons can travel through ordinary metals such as gold or copper relatively freely, strange metals resist their flow. Intriguingly, some high-temperature superconductors have a strange metal phase as well as a superconducting one. This phenomenon that cannot be explained by conventional theories that treat electrons as independent particles, ignoring any interactions between them.
To unpick these and other puzzling behaviours, a team led by Qimiao Si turned to the concept of quantum Fisher information (QFI). This statistical tool is typically used to measure how correlations between electrons evolve under extreme conditions. In this case, the team focused on a theoretical model known as the Anderson/Kondo lattice that describes how magnetic moments are coupled to electron spins in a material.
Correlations become strongest when strange metallicity appears
These analyses revealed that electron-electron correlations become strongest at precisely the point at which strange metallicity appears in a material. “In other words, the electrons become maximally entangled at this quantum critical point,” Si explains. “Indeed, the peak signals a dramatic amplification of multipartite electron spin entanglement, leading to a complex web of quantum correlations between many electrons.”
What is striking, he adds, is that this surge of entanglement provides a new and positive characterization of why strange metals are so strange, while also revealing why conventional theory fails. “It’s not just that traditional theory falls short, it is that it overlooks this rich web of quantum correlations, which prevents the survival of individual electrons as the elementary objects in this metallic substance,” he explains.
To test their finding, the researchers, who report their work in Nature Communications, compared their predictions with neutron scattering data from real strange-metal materials. They found that the experimental data was a good match. “Our earlier studies had also led us to suspect that strange metals might host a deeply entangled electron fluid – one whose hidden quantum complexity had yet to be fully understood,” adds Si.
The implications of this work are far-reaching, he tells Physics World. “Strange metals may hold the key to unlocking the next generation of superconductors — materials poised to transform how we transmit energy and, perhaps one day, eliminate power loss from the electric grid altogether.”
The Rice researchers say they now plan to explore how QFI manifests itself in the charge of electrons as well as their spins. “Until now, our focus has only been on the QFI associated with electrons spins, but electrons also of course carry charge,” Si says.
Boeing announced April 16 it has built the ground-based twin for a mission aiming to demonstrate quantum networking in space, marking a key milestone ahead of launching a small satellite called Q4S next year.
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Researchers from the Karlsruhe Tritium Neutrino experiment (KATRIN) have announced the most precise upper limit yet on the neutrino’s mass. Thanks to new data and upgraded techniques, the new limit – 0.45 electron volts (eV) at 90% confidence – is half that of the previous tightest constraint, and marks a step toward answering one of particle physics’ longest-standing questions.
Neutrinos are ghostlike particles that barely interact with matter, slipping through the universe almost unnoticed. They come in three types, or flavours: electron, muon, and tau. For decades, physicists assumed all three were massless, but that changed in the late 1990s when experiments revealed that neutrinos can oscillate between flavours as they travel. This flavour-shifting behaviour is only possible if neutrinos have mass.
Although neutrino oscillation experiments confirmed that neutrinos have mass, and showed that the masses of the three flavours are different, they did not divulge the actual scale of these masses. Doing so requires an entirely different approach.
Looking for clues in electrons
In KATRIN’s case, that means focusing on a process called tritium beta decay, where a tritium nucleus (a proton and two neutrons) decays into a helium-3 nucleus (two protons and one neutron) by releasing an electron and an electron antineutrino. Due to energy conservation, the total energy from the decay is shared between the electron and the antineutrino. The neutrino’s mass determines the balance of the split.
“If the neutrino has even a tiny mass, it slightly lowers the energy that the electron can carry away,” explains Christoph Wiesinger, a physicist at the Technical University of Munich, Germany and a member of the KATRIN collaboration. “By measuring that [electron] spectrum with extreme precision, we can infer how heavy the neutrino is.”
Because the subtle effects of neutrino mass are most visible in decays where the neutrino carries away very little energy (most of it bound up in mass), KATRIN concentrates on measuring electrons that have taken the lion’s share. From these measurements, physicists can calculate neutrino mass without having to detect these notoriously weakly-interacting particles directly.
Improvements over previous results
The new neutrino mass limit is based on data taken between 2019 and 2021, with 259 days of operations yielding over 36 million electron measurements. “That’s six times more than the previous result,” Wiesinger says.
Other improvements include better temperature control in the tritium source and a new calibration method using a monoenergetic krypton source. “We were able to reduce background noise rates by a factor of two, which really helped the precision,” he adds.
Keeping track: Laser system for the analysis of the tritium gas composition at KATRIN’s Windowless Gaseous Tritium Source. Improvements to temperature control in this source helped raise the precision of the neutrino mass limit. (Courtesy: Tritium Laboratory, KIT)
At 0.45 eV, the new limit means the neutrino is at least a million times lighter than the electron. “This is a fundamental number,” Wiesinger says. “It tells us that neutrinos are the lightest known massive particles in the universe, and maybe that their mass has origins beyond the Standard Model.”
Despite the new tighter limit, however, definitive answers about the neutrino’s mass are still some ways off. “Neutrino oscillation experiments tell us that the lower bound on the neutrino mass is about 0.05 eV,” says Patrick Huber, a theoretical physicist at Virginia Tech, US, who was not involved in the experiment. “That’s still about 10 times smaller than the new KATRIN limit… For now, this result fits comfortably within what we expect from a Standard Model that includes neutrino mass.”
Model independence
Though Huber emphasizes that there are “no surprises” in the latest measurement, KATRIN has a key advantage over its rivals. Unlike cosmological methods, which infer neutrino mass based on how it affects the structure and evolution of the universe, KATRIN’s direct measurement is model-independent, relying only on energy and momentum conservation. “That makes it very powerful,” Wiesinger argues. “If another experiment sees a measurement in the future, it will be interesting to check if the observation matches something as clean as ours.”
KATRIN’s own measurements are ongoing, with the collaboration aiming for 1000 days of operations by the end of 2025 and a final sensitivity approaching 0.3 eV. Beyond that, the plan is to repurpose the instrument to search for sterile neutrinos – hypothetical heavier particles that don’t interact via the weak force and could be candidates for dark matter.
“We’re testing things like atomic tritium sources and ultra-precise energy detectors,” Wiesinger says. “There are exciting ideas, but it’s not yet clear what the next-generation experiment after KATRIN will look like.”
The high-street bank HSBC has worked with the NQCC, hardware provider Rigetti and the Quantum Software Lab to investigate the advantages that quantum computing could offer for detecting the signs of fraud in transactional data. (Courtesy: Shutterstock/Westend61 on Offset)
Rapid technical innovation in quantum computing is expected to yield an array of hardware platforms that can run increasingly sophisticated algorithms. In the real world, however, such technical advances will remain little more than a curiosity if they are not adopted by businesses and the public sector to drive positive change. As a result, one key priority for the UK’s National Quantum Computing Centre (NQCC) has been to help companies and other organizations to gain an early understanding of the value that quantum computing can offer for improving performance and enhancing outcomes.
To meet that objective the NQCC has supported several feasibility studies that enable commercial organizations in the UK to work alongside quantum specialists to investigate specific use cases where quantum computing could have a significant impact within their industry. One prime example is a project involving the high-street bank HSBC, which has been exploring the potential of quantum technologies for spotting the signs of fraud in financial transactions. Such fraudulent activity, which affects millions of people every year, now accounts for about 40% of all criminal offences in the UK and in 2023 generated total losses of more than £2.3 bn across all sectors of the economy.
Banks like HSBC currently exploit classical machine learning to detect fraudulent transactions, but these techniques require a large computational overhead to train the models and deliver accurate results. Quantum specialists at the bank have therefore been working with the NQCC, along with hardware provider Rigetti and the Quantum Software Lab at the University of Edinburgh, to investigate the capabilities of quantum machine learning (QML) for identifying the tell-tale indicators of fraud.
“HSBC’s involvement in this project has brought transactional fraud detection into the realm of cutting-edge technology, demonstrating our commitment to pushing the boundaries of quantum-inspired solutions for near-term benefit,” comments Philip Intallura, Group Head of Quantum Technologies at HSBC. “Our philosophy is to innovate today while preparing for the quantum advantage of tomorrow.”
Another study focused on a key problem in the aviation industry that has a direct impact on fuel consumption and the amount of carbon emissions produced during a flight. In this logistical challenge, the aim was to find the optimal way to load cargo containers onto a commercial aircraft. One motivation was to maximize the amount of cargo that can be carried, the other was to balance the weight of the cargo to reduce drag and improve fuel efficiency.
“Even a small shift in the centre of gravity can have a big effect,” explains Salvatore Sinno of technology solutions company Unisys, who worked on the project along with applications engineers at the NQCC and mathematicians at the University of Newcastle. “On a Boeing 747 a displacement of just 75 cm can increase the carbon emissions on a flight of 10,000 miles by four tonnes, and also increases the fuel costs for the airline company.”
A hybrid quantum–classical solution has been used to optimize the configuration of air freight, which can improve fuel efficiency and lower carbon emissions. (Courtesy: Shutterstock/supakitswn)
With such a large number of possible loading combinations, classical computers cannot produce an exact solution for the optimal arrangement of cargo containers. In their project the team improved the precision of the solution by combining quantum annealing with high-performance computing, a hybrid approach that Unisys believes can offer immediate value for complex optimization problems. “We have reached the limit of what we can achieve with classical computing, and with this work we have shown the benefit of incorporating an element of quantum processing into our solution,” explains Sinno.
The HSBC project team also found that a hybrid quantum–classical solution could provide an immediate performance boost for detecting anomalous transactions. In this case, a quantum simulator running on a classical computer was used to run quantum algorithms for machine learning. “These simulators allow us to execute simple QML programmes, even though they can’t be run to the same level of complexity as we could achieve with a physical quantum processor,” explains Marco Paini, the project lead for Rigetti. “These simulations show the potential of these low-depth QML programmes for fraud detection in the near term.”
The team also simulated more complex QML approaches using a similar but smaller-scale problem, demonstrating a further improvement in performance. This outcome suggests that running deeper QML algorithms on a physical quantum processor could deliver an advantage for detecting anomalies in larger datasets, even though the hardware does not yet provide the performance needed to achieve reliable results. “This initiative not only showcases the near-term applicability of advanced fraud models, but it also equips us with the expertise to leverage QML methods as quantum computing scales,” comments Intellura.
Indeed, the results obtained so far have enabled the project partners to develop a roadmap that will guide their ongoing development work as the hardware matures. One key insight, for example, is that even a fault-tolerant quantum computer would struggle to process the huge financial datasets produced by a bank like HSBC, since a finite amount of time is needed to run the quantum calculation for each data point. “From the simulations we found that the hybrid quantum–classical solution produces more false positives than classical methods,” says Paini. “One approach we can explore would be to use the simulations to flag suspicious transactions and then run the deeper algorithms on a quantum processor to analyse the filtered results.”
This particular project also highlighted the need for agreed protocols to navigate the strict rules on data security within the banking sector. For this project the HSBC team was able to run the QML simulations on its existing computing infrastructure, avoiding the need to share sensitive financial data with external partners. In the longer term, however, banks will need reassurance that their customer information can be protected when processed using a quantum computer. Anticipating this need, the NQCC has already started to work with regulators such as the Financial Conduct Authority, which is exploring some of the key considerations around privacy and data security, with that initial work feeding into international initiatives that are starting to consider the regulatory frameworks for using quantum computing within the financial sector.
For the cargo-loading project, meanwhile, Sinno says that an important learning point has been the need to formulate the problem in a way that can be tackled by the current generation of quantum computers. In practical terms that means defining constraints that reduce the complexity of the problem, but that still reflect the requirements of the real-world scenario. “Working with the applications engineers at the NQCC has helped us to understand what is possible with today’s quantum hardware, and how to make the quantum algorithms more viable for our particular problem,” he says. “Participating in these studies is a great way to learn and has allowed us to start using these emerging quantum technologies without taking a huge risk.”
Indeed, one key feature of these feasibility studies is the opportunity they offer for different project partners to learn from each other. Each project includes an end-user organization with a deep knowledge of the problem, quantum specialists who understand the capabilities and limitations of present-day solutions, and academic experts who offer an insight into emerging theoretical approaches as well as methodologies for benchmarking the results. The domain knowledge provided by the end users is particularly important, says Paini, to guide ongoing development work within the quantum sector. “If we only focused on the hardware for the next few years, we might come up with a better technical solution but it might not address the right problem,” he says. “We need to know where quantum computing will be useful, and to find that convergence we need to develop the applications alongside the algorithms and the hardware.”
Another major outcome from these projects has been the ability to make new connections and identify opportunities for future collaborations. As a national facility NQCC has played an important role in providing networking opportunities that bring diverse stakeholders together, creating a community of end users and technology providers, and supporting project partners with an expert and independent view of emerging quantum technologies. The NQCC has also helped the project teams to share their results more widely, generating positive feedback from the wider community that has already sparked new ideas and interactions.
“We have been able to network with start-up companies and larger enterprise firms, and with the NQCC we are already working with them to develop some proof-of-concept projects,” says Sinno. “Having access to that wider network will be really important as we continue to develop our expertise and capability in quantum computing.”
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Through new experiments, researchers in Switzerland have tested models of how microwaves affect low-temperature chemical reactions between ions and molecules. Through their innovative setup, Valentina Zhelyazkova and colleagues at ETH Zurich showed for the first time how the application of microwave pulses can slow down reaction rates via nonthermal mechanisms.
Physicists have been studying chemical reactions between ions and neutral molecules for some time. At close to room temperature, classical models can closely predict how the electric fields emanating from ions will induce dipoles in nearby neutral molecules, allowing researchers to calculate these reaction rates with impressive accuracy. Yet as temperatures drop close to absolute zero, a wide array of more complex effects come into play, which have gradually been incorporated into the latest theoretical models.
“At low temperatures, models of reactivity must include the effects of the permanent electric dipoles and quadrupole moments of the molecules, the effect of their vibrational and rotational motion,” Zhelyazkova explains. “At extremely low temperatures, even the quantum-mechanical wave nature of the reactants must be considered.”
Rigorous experiments
Although these low-temperature models have steadily improved in recent years, the ability to put them to the test through rigorous experiments has so far been hampered by external factors.
In particular, stray electric fields in the surrounding environment can heat the ions and molecules, so that any important quantum effects are quickly drowned out by noise. “Consequently, it is only in the past few years that experiments have provided information on the rates of ion–molecule reactions at very low temperatures,” Zhelyazkova explains.
In their study, Zhelyazkova’s team improved on these past experiments through an innovative approach to cooling the internal motions of the molecules being heated by stray electric fields. Their experiment involved a reaction between positively-charged helium ions and neutral molecules of carbon monoxide (CO). This creates neutral atoms of helium and oxygen, and a positively-charged carbon atom.
To initiate the reaction, the researchers created separate but parallel supersonic beams of helium and CO that were combined in a reaction cell. “In order to overcome the problem of heating the ions by stray electric fields, we study the reactions within the distant orbit of a highly excited electron, which makes the overall system electrically neutral without affecting the ion–molecule reaction taking place within the electron orbit,” explains ETH’s Frédéric Merkt.
Giant atoms
In such a “Rydberg atom”, the highly excited electron is some distance from the helium nucleus and its other electron. As a result, a Rydberg helium atom can be considered an ion with a “spectator” electron, which has little influence over how the reaction unfolds. To ensure the best possible accuracy, “we use a printed circuit board device with carefully designed surface electrodes to deflect one of the two beams,” explains ETH’s, Fernanda Martins. “We then merged this beam with the other, and controlled the relative velocity of the two beams.”
Altogether, this approach enabled the researchers to cool the molecules internally to temperatures below 10 K – where their quantum effects can dominate over externally induced noise. With this setup, Zhelyazkova, Merkt, Martins, and their colleagues could finally put the latest theoretical models to the test.
According to the latest low-temperature models, the rate of the CO–helium ion reaction should be determined by the quantized rotational states of the CO molecule – whose energies lie within the microwave range. In this case, the team used microwave pulses to put the CO into different rotational states, allowing them to directly probe their influence on the overall reaction rate.
Three important findings
Altogether, their experiment yielded three important findings. It confirmed that the reaction rate can vary, depending on the rotational state of the CO molecule; it showed that this reactivity can be modified by using a short microwave pulse to excite the CO molecule from its ground state to its first excited state – with the first excited state being less reactive than the ground state.
The third and most counterintuitive finding is that microwaves can slow down the reaction rate, via mechanisms unrelated to the heat they impart on the molecules absorbing them. “In most applications of microwaves in chemical synthesis, the microwaves are used as a way to thermally heat the molecules up, which always makes them more reactive,” Zhelyazkova says.
Building on the success of their experimental approach, the team now hopes to investigate these nonthermal mechanisms in more detail – with the aim to shed new light on how microwaves can influence chemical reactions via effects other than heating. In turn, their results could ultimately pave the way for advanced new techniques for fine-tuning the rate of reactions between ions and neutral molecules.
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