Firm evidence of Majorana bound states in quantum dots has been reported by researchers in the Netherlands. Majorana modes appeared at both edges of a quantum dot chain when an energy gap suppressed them in the centre, and the experiment could allow researchers to investigate the unique properties of these particles in hitherto unprecedented detail. This could bring topologically protected quantum bits (qubits) for quantum computing one step closer.
Majorana fermions were first proposed in 1937 by the Italian physicist Ettore Majorana. They were imagined as elementary particles that would be their own antiparticles. However, such elementary particles have never been definitively observed. Instead, physicists have worked to create Majorana quasiparticles (particle-like collective excitations) in condensed matter systems.
In 2001, the theoretical physicist Alexei Kitaev at Microsoft Research, proposed that “Majorana bound states” could be produced in nanowires comprising topological superconductors. The Majorana quasiparticle would exist as a single nonlocal mode at either end of a wire, while being zero-valued in the centre. Both ends would be constrained by the laws of physics to remain identical despite being spatially separated. This phenomenon could produce “topological qubits” robust to local disturbance.
Microsoft and others continue to research Majorana modes using this platform to this day. Multiple groups claim to have observed them, but this remains controversial. “It’s still a matter of debate in these extended 1D systems: have people seen them? Have they not seen them?”, says Srijit Goswami of QuTech in Delft.
In 2012, theoretical physicists Jay Sau, then of Harvard University and Sankar Das Sarma of the University of Maryland proposed looking for Majorana bound states in quantum dots. “We looked at [the nanowires] and thought ‘OK, this is going to be a while given the amount of disorder that system has – what are the ways this disorder could be controlled?’ and this is exactly one of the ways we thought it could work,” explains Sau. The research was not taken seriously at the time, however, Sau says, partly because people underestimated the problem of disorder.
Goswami and others have previously observed “poor man’s Majoranas” (PMMs) in two quantum dots. While they share some properties with Majorana modes, PMMs lack topological protection. Last year the group coupled two spin-polarized quantum dots connected by a semiconductor–superconductor hybrid material. At specific points, the researchers found zero-bias conductance peaks.
“Kitaev says that if you tune things exactly right you have one Majorana on one dot and another Majorana on another dot,” says Sau. “But if you’re slightly off then they’re talking to each other. So it’s an uncomfortable notion that they’re spatially separated if you just have two dots next to each other.”
Recently, a group that included Goswami’s colleagues at QuTech found that the introduction of a third quantum dot stabilized the Majorana modes. However, they were unable to measure the energy levels in the quantum dots.
In new work, Goswami’s team used systems of three electrostatically-gated, spin-polarized quantum dots in a 2D electron gas joined by hybrid semiconductor–superconductor regions. The quantum dots had to be tuned to zero energy. The dots exchanged charge in two ways: by standard electron hopping through the semiconductor and by Cooper-pair mediated coupling through the superconductor.
“You have to change the energy level of the superconductor–semiconductor hybrid region so that these two processes have equal probability,” explains Goswami. “Once you satisfy these conditions, then you get Majoranas at the ends.”
In addition to more topological protection, the addition of a third qubit provided the team with crucial physical insight. “Topology is actually a property of a bulk system,” he explains; “Something special happens in the bulk which gives rise to things happening at the edges. Majoranas are something that emerge on the edges because of something happening in the bulk.” With three quantum dots, there is a well-defined bulk and edge that can be probed separately: “We see that when you have what is called a gap in the bulk your Majoranas are protected, but if you don’t have that gap your Majoranas are not protected,” Goswami says.
To produce a qubit will require more work to achieve the controllable coupling of four Majorana bound states and the integration of a readout circuit to detect this coupling. In the near-term, the researchers are investigating other phenomena, such as the potential to swap Majorana bound states.
Sau is now at the University of Maryland and says that an important benefit of the experimental platform is that it can be determined unambiguously whether or not Majorana bound states have been observed. “You can literally put a theory simulation next to the experiment and they look very similar.”
The research is published in Nature.
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NASA released more details about its proposed fiscal year 2026 budget May 30, canceling dozens of science missions and cutting thousands of jobs.
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GPS III SV-08, built by Lockheed Martin, is the eighth of 10 GPS III spacecraft.
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The Leinweber Foundation has awarded five US institutions $90m to create their own theoretical research institutes. The investment, which the foundation says is the largest ever for theoretical physics research, will be used to fund graduate students and postdocs at each institute as well as several Leinweber Physics Fellows.
The Leinweber Foundation was founded in 2015 by the software entrepreneur Larry Leinweber. In 1982 Leinweber founded the software company New World Systems Corporation, which provided software to the emergency services. In 2015 he sold the company to Tyler Technologies for $670m.
Based in Michigan, Leinweber Foundation supports research, education and community endeavours where it has provided Leinweber Software Scholarships to undergraduates at Michigan’s universities.
A Leinweber Institute for Theoretical Physics (LITP) will now be created at the universities of California, Berkeley, Chicago and Michigan as well as at the Massachusetts Institute of Technology (MIT) and at Princeton’s Institute for Advanced Study (IAS), where the institute will instead be named the Leinweber Forum for Theoretical and Quantum Physics.
The MIT LIPT, initially led by Washington Taylor before physicist Tracy Slatyer takes over later this year, will receive $20m from the foundation and will provide support for six postdocs, six graduate students as well as visitors, seminars and “other scholarly activities”.
“This landmark endowment from the Leinweber Foundation will enable us to support the best graduate students and postdoctoral researchers to develop their own independent research programmes and to connect with other researchers in the Leinweber Institute network,” says Taylor.
UC Berkeley, meanwhile, will receive $14.4m from the foundation in which the existing Berkeley Center for Theoretical Physics (BITP) will be renamed LITP at Berkeley and led by physicist Yasunori Nomura.
The money will be used for four postdoc positions to join the existing 15 at the BITP as well as to support graduate students and visitors. “This is transformative,” notes Nomura. “The gift will really have a huge impact on a wide range of research at Berkeley, including particle physics, quantum gravity, quantum information, condensed matter physics and cosmology.”
Chicago will receive $18.4m where the existing Kadanoff Center for Theoretical Physics will be merged into a new LITP at the University of Chicago and led by physicist Dam Thanh Son.
The remaining $37.2m will be split between the Leinweber Forum for Theoretical and Quantum Physics at the IAS and at Michigan, in which the existing Leinweber Center for Theoretical Physics will expand and become an institute.
“Theoretical physics may seem abstract to many, but it is the tip of the spear for innovation. It fuels our understanding of how the world works and opens the door to new technologies that can shape society for generations,” says Leinweber in a statement. “As someone who has had a lifelong fascination with theoretical physics, I hope this investment not only strengthens U.S. leadership in basic science, but also inspires curiosity, creativity, and groundbreaking discoveries for generations to come.”
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Despite a surge of interest in Europe in establishing autonomy in space systems, there remains skepticism that one of the biggest efforts along those lines.
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China has launched its first mission to retrieve samples from an asteroid. The Tianwen-2 mission launched at 01:31 a.m. local time on 28 May from the Xichang satellite launch center, southwest China, aboard a Long March B rocket.
Tianwen-2’s target is a small near-Earth asteroid called 469219 Kamoʻoalewa, which is between 15-39 million km away and is known as a “quasi-satellite” of Earth.
The mission is set to reach the body, which is between 40-100 m wide, in July 2026 where it will first study it up close using a suite of 11 instruments including cameras, spectrometers and radar, before aiming to collect about 100 g of material.
This will be achieved via three possible methods. One is via hovering close to the asteroid , the other is using a robotic arm to collect samples from the body while a third is dubbed “touch and go”, which involves gently landing on the asteroid and using drills at the end of each leg to retrieve material.
The collected samples will then be stored in a module that is released and returned to Earth in November 2027. If successful, it will make China the third nation to retrieve asteroid material behind the US and Japan.
The second part of the 10-year mission involves using Earth for a gravitational swing-by to spend six year travelling to another target – 311P/PanSTARRS. The body lies in the main asteroid belt between Mars and Jupiter and at its closest distance is about 140 million km away from Earth.
The 480 m-wide object, which was discovered in 2013, has six dust tails and has characteristics of both asteroids and comets. Tianwen-2 will not land on 311P/PanSTARRS but instead use its instruments to study the “active asteroid” from a distance.
Tianwen-2’s predecessor, Tianwen-1, was China’s first mission to Mars, successfully landing on Utopia Planitia – a largely flat impact basin but scientifically interesting with potential water-ice underneath – following a six-month journey.
China’s third interplanetary mission, Tianwen-3, will aim to retrieve sample from Mars and could launch as soon as 2028. If successful, it would make China the first country to achieve the feat.
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Researchers in China have adapted the interlocking structure of mortise-and-tenon joints – as used by woodworkers around the world since ancient times – to the design of nanoscale devices known as memristors. The new devices are far more uniform than previous such structures, and the researchers say they could be ideal for scientific computing applications.
The memory-resistor, or “memristor”, was described theoretically at the beginning of the 1970s, but the first practical version was not built until 2008. Unlike standard resistors, the resistance of a memristor changes depending on the current previously applied to it, hence the “memory” in its name. This means that a desired resistance can be programmed into the device and subsequently stored. Importantly, the remembered value of the resistive state persists even when the power is switched off.
Thanks to numerous technical advances since 2008, memristors can now be integrated onto chips in large numbers. They are also capable of processing large amounts of data in parallel, meaning they could be ideal for emerging “in-memory” computing technologies that require calculations known as large-scale matrix-vector multiplications (MVMs). Many such calculations involve solving partial differential equations (PDEs), which are used to model complex behaviour in fields such as weather forecasting, fluid dynamics and astrophysics, to name but a few.
One remaining hurdle, however, is that it is hard to make memristors with uniform characteristics. The electronic properties of devices containing multiple memristors can therefore vary considerably, which adversely affects the computational accuracy of large-scale arrays.
Physicists co-led by Shi-Jun Liang and Feng Miao of Nanjing University’s School of Physics say they have now overcome this problem by designing a memristor that uses a mortise-tenon-shaped (MTS) architecture. Humans have been using these strong and stable structures in wooden furniture for thousands of years, with one of the earliest examples dating back to the Hemudu culture in China 7 000 years ago.
Liang, Miao and colleagues created the mortise part of their structure by using plasma etching to create a hole within a nanosized-layer of hexagonal boron nitride (h-BN). They then constructed a tenon in a top electrode made of tantalum (Ta) that precisely matches the mortise. This ensures that this electrode directly contacts the device’s switching layer (which is made from HfO2) only in the designated region. A bottom electrode completes the device.
The new architecture ensures highly uniform switching within the designated mortise-and-tenon region, resulting in a localized path for electronic conduction. “The result is a memristor with exceptional fundamental properties across three key metrics,” Miao tells Physics World. “These are: high endurance (over more than 109 cycles); long-term and stable memory retention (of over 104 s), and a fast switching speed of around 4.2 ns.”
The cycle-to-cycle variation of the low-resistance state (LRS) can also be reduced from 30.3% for a traditional memristor to 2.5% for the MTS architecture and the high-resistance state (HRS) from 62.4 to 27.2%.
To test their device, the researchers built a PDE solver with it. They found that their new MTS memristor could solve the Poisson equation five times faster than a conventional memristor based on HfO2 without h-BN.
The new technique, which is detailed in Science Advances, is a promising strategy for developing high-uniformity memristors, and could pave the way for high-accuracy, energy-efficient scientific computing platforms, Liang claims. “We are now looking to develop large-scale integration of our MTS device and make a prototype system,” he says.
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On April 28, Spain experienced one of the most extensive power outages in recent memory. Millions of citizens and businesses were suddenly cut off, revealing how unprepared even developed nations […]
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A new contact lens enables humans to see near-infrared light without night vision goggles or other bulky equipment. The lens, which incorporates metallic nanoparticles that “upconvert” normally-invisible wavelengths into visible ones, could have applications for rescue workers and others who would benefit from enhanced vision in conditions with poor visibility.
The infrared (IR) part of the electromagnetic spectrum encompasses light with wavelengths between 700 nm and 1 mm. Human eyes cannot normally detect these wavelengths because opsins, the light-sensitive protein molecules that allow us to see, do not have the required thermodynamic properties. This means we see only a small fraction of the electromagnetic spectrum, typically between 400‒700 nm.
While devices such as night vision goggles and infrared-visible converters can extend this range, they require external power sources. They also cannot distinguish between different wavelengths of IR light.
In a previous work, researchers led by neuroscientist Tian Xue of the University of Science and Technology of China (USTC) injected photoreceptor-binding nanoparticles into the retinas of mice. While this technique was effective, it is too invasive and risky for human volunteers. In the new study, therefore, Xue and colleagues integrated the nanoparticles into biocompatible polymeric materials similar to those used in standard soft contact lenses.
The nanoparticles in the lenses are made from Au/NaGdF4: Yb3+, Er3+ and have a diameter of approximately 45 nm each. They work by capturing photons with lower energies (longer wavelengths) and re-emitting them as photons with higher energies (shorter wavelengths). This process is known as upconversion and the emitted light is said to be anti-Stokes shifted.
When the researchers tested the new upconverting contact lenses (UCLs) on mice, the rodents’ behaviour suggested they could sense IR wavelengths. For example, when given a choice between a dark box and an IR-illuminated one, the lens-wearing mice scurried into the dark box. In contrast, a control group of mice not wearing lenses showed no preference for one box over the other. The pupils of the lens-wearing mice also constricted when exposed to IR light, and brain imaging revealed that processing centres in their visual cortex were activated.
The team then moved on to human volunteers. “In humans, the near-infrared UCLs enabled participants to accurately detect flashing Morse code-like signals and perceive the incoming direction of near-infrared (NIR) light,” Xue says, referring to light at wavelengths between 800‒1600 nm. Counterintuitively, the flashing images appeared even clearer when the volunteers closed their eyes – probably because IR light is better than visible light at penetrating biological tissue such as eyelids. Importantly, Xue notes that wearing the lenses did not affect participants’ normal vision.
The team also developed a wearable system with built-in flat UCLs. This system allowed volunteers to distinguish between patterns such as horizontal and vertical lines; S and O shapes; and triangles and squares.
But Xue and colleagues did not stop there. By replacing the upconverting nanoparticles with trichromatic orthogonal ones, they succeeded in converting NIR light into three different spectral bands. For example, they converted infrared wavelengths of 808, 980 nm and 1532 nm into 540, 450, and 650 nm respectively – wavelengths that humans perceive as green, blue and red.
“As well as allowing wearers to garner more detail within the infrared spectrum, this technology could also help colour-blind individuals see wavelengths they would otherwise be unable to detect by appropriately adjusting the absorption spectrum,” Xue tells Physics World.
According to the USTC researchers, who report their work in Cell, the devices could have several other applications. Apart from providing humans with night vision and offering an adaptation for colour blindness, the lenses could also give wearers better vision in foggy or dusty conditions.
At present, the devices only work with relatively bright IR emissions (the study used LEDs). However, the researchers hope to increase the photosensitivity of the nanoparticles so that lower levels of light can trigger the upconversion process.
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The University of Colorado, Boulder, is preparing to announce the establishment of the Colorado Space Policy Center (CSPC).
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Astronstone, one of China’s newest commercial launch startups, has raised early-stage funding for a stainless steel, reusable launch vehicle modeled on SpaceX’s Starship system.
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Powerful flares on highly-magnetic neutron stars called magnetars could produce up to 10% of the universe’s gold, silver and platinum, according to a new study. What is more, astronomers may have already observed this cosmic alchemy in action.
Gold, silver, platinum and a host of other rare heavy nuclei are known as rapid-process (r-process) elements. This is because astronomers believe that these elements are produced by the rapid capture of neutrons by lighter nuclei. Neutrons can only exist outside of an atomic nucleus for about 15 min before decaying (except in the most extreme environments). This means that the r-process must be fast and take place in environments rich in free neutrons.
In August 2017, an explosion resulting from the merger of two neutron stars was witnessed by telescopes operating across the electromagnetic spectrum and by gravitational-wave detectors. Dubbed a kilonova, the explosion produced approximately 16,000 Earth-masses worth of r-process elements, including about ten Earth masses of gold and platinum.
While the observations seem to answer the question of where precious metals came from, there remains a suspicion that neutron-star mergers cannot explain the entire abundance of r-process elements in the universe.
Now researchers led by Anirudh Patel, who is a PhD student at New York’s Columbia University, have created a model that describes how flares on the surface of magnetars can create r-process elements.
Patel tells Physics World that “The rate of giant flares is significantly greater than mergers.” However, given that one merger “produces roughly 10,000 times more r-process mass than a single magnetar flare”, neutron-star mergers are still the dominant factory of rare heavy elements.
A magnetar is an extreme type of neutron star with a magnetic field strength of up to a thousand trillion gauss. This makes magnetars the most magnetic objects in the universe. Indeed, if a magnetar were as close to Earth as the Moon, its magnetic field would wipe your credit card.
Astrophysicists believe that when a magnetar’s powerful magnetic fields are pulled taut, the magnetic tension will inevitably snap. This would result in a flare, which is an energetic ejection of neutron-rich material from the magnetar’s surface.
However, the physics isn’t entirely understood, according to Jakub Cehula of Charles University in the Czech Republic, who is a member of Patel’s team. “While the source of energy for a magnetar’s giant flares is generally agreed to be the magnetic field, the exact mechanism by which this energy is released is not fully understood,” he explains.
One possible mechanism is magnetic reconnection, which creates flares on the Sun. Flares could also be produced by energy released during starquakes following a build-up of magnetic stress. However, neither satisfactorily explains the giant flares, of which only nine have thus far been detected.
In 2024 Cehula led research that attempted to explain the flares by combining starquakes with magnetic reconnection. “We assumed that giant flares are powered by a sudden and total dissipation of the magnetic field right above a magnetar’s surface,” says Cehula.
This sudden release of energy drives a shockwave into the magnetar’s neutron-rich crust, blasting a portion of it into space at velocities greater than a tenth of the speed of light, where in theory heavy elements are formed via the r-process.
Remarkably, astronomers may have already witnessed this in 2004, when a giant magnetar flare was spotted as a half-second gamma-ray burst that released more energy than the Sun does in a million years. What happened next remained unexplained until now. Ten minutes after the initial burst, the European Space Agency’s INTEGRAL satellite detected a second, weaker signal that was not understood.
Now, Patel and colleagues have shown that the r-process in this flare created unstable isotopes that quickly decayed into stable heavy elements – creating the gamma-ray signal.
Patel calculates that the 2004 flare resulted in the creation of two million billion billion kilograms of r-process elements, equivalent to about the mass of Mars.
Extrapolating, Patel calculates that giant flares on magnetars contribute between 1–10% of all the r-process elements in the universe.
“This estimate accounts for the fact that these giant flares are rare,” he says, “But it’s also important to note that magnetars have lifetimes of 1000 to 10,000 years, so while there may only be a couple of dozen magnetars known to us today, there have been many more magnetars that have lived and died over the course of the 13 billion-year history of our galaxy.”
Magnetars would have been produced early in the universe by the supernovae of massive stars, whereas it can take a billion years or longer for two neutron stars to merge. Hence, magnetars would have been a more dominant source of r-process elements in the early universe. However, they may not have been the only source.
“If I had to bet, I would say there are other environments in which r-process elements can be produced, for example in certain rare types of core-collapse supernovae,” says Patel.
Either way, it means that some of the gold and silver in your jewellery was forged in the violence of immense magnetic fields snapping on a dead star.
The research is described in Astrophysical Journal Letters.
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“We’re not done,” Rocket Lab CEO Peter Beck told SpaceNews
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China carried out its ninth launch of the month early Thursday, sending the secretive Shijian-26 spacecraft into orbit.
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Northrop Grumman is investing $50 million into Firefly Aerospace to further development of a medium-lift launch vehicle with a new name.
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At the core of Beijing's campaign are advanced data centers, on Earth and in orbit
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Join us on May 6 for a timely discussion on those challenging Starlink and the push for multi-orbit and multi-operator solutions.
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Quantum science is enjoying a renaissance as nascent quantum computers emerge from the lab and quantum sensors are being used for practical applications.
As the technologies we use become more quantum in nature, it follows that everyone should have a basic understanding of quantum physics. To explore how quantum physics can be taught to the masses, I am joined by Arjan Dhawan, Aleks Kissinger and Bob Coecke – who are all based in the UK.
Coecke is chief scientist at Quantinuum – which develops quantum computing hardware and software. Kissinger is associate professor of quantum computing at the University of Oxford; and Dhawan is studying mathematics at the University of Durham.
Kissinger and Coecke have developed a way of teaching quantum physics using diagrams. In 2023, Oxford and Quantinuum joined forces to use the method in a pilot summer programme for 15 to 17 year-olds. Dhawan was one of their students.
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This article forms part of Physics World‘s contribution to the 2025 International Year of Quantum Science and Technology (IYQ), which aims to raise global awareness of quantum physics and its applications.
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