The Space Force last year awarded Lockheed Martin and Boeing $66 million each for the first phase of the MUOS Service Life Extension program
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The proposed legislation includes $960 million for space-based technologies
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Boeing has notified employees working on the Space Launch System program that up to 400 of them could lose their jobs.
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The Federal Communications Commission looks set to launch a process to review new uses for upper C-band satellite spectrum at its first open meeting under Chairman Brendan Carr Feb. 27, potentially setting up a battle between SpaceX and U.S. wireless carriers.
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A bipartisan group of senators has reintroduced a bill to formally authorize a space traffic coordination system being developed by the Office of Space Commerce.
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The Canadian Space Agency awarded a contract Feb. 7 to Spire Global, partnered with OroraTech, to develop a constellation of cubesats to monitor wildfires.
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The second Trump administration has started with a series of rapid changes to how the federal government operates. Here’s what the president introduced in the last week and what it […]
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Unexpected behaviour at phase transitions between classical and quantum magnetism has been observed in different quantum simulators operated by two independent groups. One investigation was led by researchers at Harvard University and used Rydberg atom as quantum bits (qubits). The other study was led by scientists at Google Research and involved superconducting qubits. Both projects revealed unexpected deviations from the canonical mechanisms of magnetic freezing, with unexpected oscillations near the phase transition.
A classical magnetic material can be understood as a fluid mixture of magnetic domains that are oriented in opposite directions, with the domain walls in constant motion. As a strengthening magnetic field is applied to the system, the energy associated with a domain wall increases, so the magnetic domains themselves become larger and less mobile. At some point, when the magnetism becomes sufficiently strong, a quantum phase transition occurs, causing the magnetism of the material to become fixed and crystalline: “A good analogy is like water freezing,” says Mikhail Lukin of Harvard University.
The traditional quantitative model for these transitions is the Kibble–Zurek mechanism, which was first formulated to describe cosmological phase transitions in the early universe. It predicts that the dynamics of a system begin to “freeze” when the system gets so close to the transition point that the domains crystallize more quickly than they can come to equilibrium.
“There are some very good theories of various types of quantum phase transitions that have been developed,” says Lukin, “but typically these theories make some approximations. In many cases they’re fantastic approximations that allow you to get very good results, but they make some assumptions which may or may not be correct.”
In their work, Lukin and colleagues utilized a highly reconfigurable platform using Rydberg atom qubits. The system was pioneered by Lukin and others in 2016 to study a specific type of magnetic quantum phase transition in detail. They used a laser to simulate the effect of a magnetic field on the Rydberg atoms, and adjusted the laser frequency to tune the field strength.
The researchers found that, rather than simply becoming progressively larger and less mobile as the field strength increased (a phenomenon called coarsening), the domain sizes underwent unexpected oscillations around the phase transition.
“We were really quite puzzled,” says Lukin. “Eventually we figured out that this oscillation is a sign of a special type of excitation mode similar to the Higgs mode in high-energy physics. This is something we did not anticipate…That’s an example where doing quantum simulations on quantum devices really can lead to new discoveries.”
Meanwhile, the Google-led study used a new approach to quantum simulation with superconducting qubits. Such qubits have proved extremely successful and scalable because they use solid-state technology – and they are used in most of the world’s leading commercial quantum computers such as IBM’s Osprey and Google’s own Willow chips. Much of the previous work using such chips, however, has focused on sequential “digital” quantum logic in which one set of gates is activated only after the previous set has concluded. The long times needed for such calculations allows the effects of noise to accumulate, resulting in computational errors.
In the new work, the Google team developed a hybrid analogue–digital approach in which a digital universal quantum gate set was used to prepare well-defined input qubit states. They then switched the processor to analogue mode, using capacitive couplers to tune the interactions between the qubits. In this mode, all the qubits were allowed to operate on each other simultaneously, without the quantum logic being shoehorned into a linear set of gate operations. Finally, the researchers characterized the output by switching back to digital mode.
The researchers used a 69-qubit superconducting system to simulate a similar, but non-identical, magnetic quantum phase transition to that studied by Lukin’s group. They were also puzzled by similar unexpected behaviour in their system. The groups’ subsequently became aware of each other’s work, as Google Research’s Trond Anderson explains: “It’s very exciting to see consistent observations from the Lukin group. This not only provides supporting evidence, but also demonstrates that the phenomenon appears in several contexts, making it extra important to understand”.
Both groups are now seeking to push their research deeper into the exploration of complex many-body quantum physics. The Google group estimates that, to conduct its simulations of the highly entangled quantum states involved with the same level of experimental fidelity would take the US Department of Energy’s Frontier supercomputer – one of the world’s most powerful – more than a million years. The researchers now want to look at problems that are completely intractable classically, such as magnetic frustration. “The analogue–digital approach really combines the best of both worlds, and we’re very excited about this as a new promising direction towards making discoveries in systems that are too complex for classical computers,” says Anderson.
The Harvard researchers are also looking to push their system to study more and more complex quantum systems. “There are many interesting processes where dynamics – especially across a quantum phase transition – remains poorly understood,” says Lukin. “And it ranges from the science of complex quantum materials to systems in high-energy physics such as lattice gauge theories, which are notorious for being hard to simulate classically to the point where people literally give up…We want to apply these kinds of simulators to real open quantum problems and really use them to study the dynamics of these systems.”
The research is described in side-by-side papers in Nature. The Google paper is here and the Harvard paper here.
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For more than five years, astronomers have sounded alarms about the effect satellite megaconstellations would have on their observations. The launch in 2019 of the first Starlink satellites, initially bright […]
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Join us Feb. 19 as we discuss the state space sustainability and orbital traffic management and how they work together to ensure the long-term safety and usability of outer space.
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Top Democrats on two committees are raising concerns about conflicts of interest between a government organization led by Elon Musk and two agencies.
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HELSINKI — Chinese low Earth orbit megaconstellation operator Spacesail has signed an agreement with Measat to expand its presence into Southeast Asia. Chinese low Earth orbit (LEO) satellite operator Shanghai […]
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An international team of researchers has detected a series of significant X-ray oscillations near the innermost orbit of a supermassive black hole – an unprecedented discovery that could indicate the presence of a nearby stellar-mass orbiter such as a white dwarf.
The Massachusetts Institute of Technology (MIT)-led team began studying the extreme supermassive black hole 1ES 1927+654 – located around 270 million light years away and about a million times more massive than the Sun – in 2018, when it brightened by a factor of around 100 at optical wavelengths. Shortly after this optical outburst, X-ray monitoring revealed a period of dramatic variability as X-rays dropped rapidly – at first becoming undetectable for about a month, before returning with a vengeance and transforming into the brightest supermassive black hole in the X-ray sky.
“All of this dramatic variability seemed to be over by 2021, as the source appeared to have returned to its pre-2018 state. However, luckily, we continued to watch this source, having learned the lesson that this supermassive black hole will always surprise us. The discovery of these millihertz oscillations was indeed quite a surprise, but it gives us a direct probe of regions very close to the supermassive black hole,” says Megan Masterson, a fifth-year PhD candidate at the MIT Kavli Institute for Astrophysics and Space Research, who co-led the study with MIT’s Erin Kara – alongside researchers based elsewhere in the US, as well as at institutions in Chile, China, Israel, Italy, Spain and the UK.
“We found that the period of these oscillations rapidly changed – dropping from around 18 minutes in 2022 to around seven minutes in 2024. This period evolution is unprecedented, having never been seen before in the small handful of other supermassive black holes that show similar oscillatory behaviour,” she adds.
According to Masterson, one of the key ideas behind the study was that the rapid X-ray period change could be driven by a white dwarf – the compact remnant of a star like our Sun – orbiting around the supermassive black hole close to its event horizon.
“If this white dwarf is driving these oscillations, it should produce a gravitational wave signal that will be detectable with next-generation gravitational wave observatories, like ESA’s Laser Interferometer Space Antenna (LISA),” she says.
To test their hypothesis, the researchers used X-ray data from ESA’s XMM-Newton observatory to detect the oscillations, which allowed them to track how the X-ray brightness changed over time. The findings were presented in mid-January at the 245th meeting of the American Astronomical Society in National Harbor, Maryland, and subsequently reported in Nature.
According to Masterson, these insights into the behaviour of X-rays near a black hole will have major implications for future efforts to detect multi-messenger signals from supermassive black holes.
“We really don’t understand how common stellar-mass companions around supermassive black holes are, but these findings tell us that it may be possible for stellar-mass objects to survive very close to supermassive black holes and produce gravitational wave signals that will be detected with the next-generation gravitational wave observatories,” she says.
Looking ahead, Masterson confirms that the immediate next step for MIT research in this area is to continue to monitor 1ES 1927+654 – with both existing and future telescopes – in an effort to deepen understanding of the extreme physics at play in and around the innermost environments of black holes.
“We’ve learned from this discovery that we should expect the unexpected with this source,” she adds. “We’re also hoping to find other sources like this one through large time-domain surveys and dedicated X-ray follow-up of interesting transients.”
The post Supermassive black hole displays ‘unprecedented’ X-ray outbursts appeared first on Physics World.
This episode of the Physics World Weekly podcast looks at how climate and environmental change affect the efficiency of solar panels. Our guest is the climate scientist Sushovan Ghosh, who is lead author of paper that explores how aerosols, rising temperatures and other environmental factors will affect solar-energy output in India in the coming decades.
Today, India ranks fifth amongst nations in terms of installed solar-energy capacity and boosting this capacity will be crucial for the country’s drive to reduce its greenhouse gas emissions by 45% by 2030 – when compared to 2005.
While much of India is blessed with abundant sunshine, it is experiencing a persistent decline in incoming solar radiation that is associated with aerosol pollution. What is more, higher temperatures associated with climate change reduce the efficiency of solar cells – and their performance is also impacted in India by other climate-related phenomena.
In this podcast, Ghosh explains how changes in the climate and environment affect the generation of solar energy and what can be done to mitigate these effects.
Ghosh co-wrote the paper when at the Centre for Atmospheric Sciences at the Indian Institute of Technology Delhi and he is now at the Barcelona Supercomputing Center in Spain. His co-authors in Delhi were Dilip Ganguly, Sagnik Dey and Subhojit Ghoshal Chowdhury; and the paper is called, “Future photovoltaic potential in India: navigating the interplay between air pollution control and climate change mitigation”. It appears in Environmental Research Letters, which is published by IOP Publishing – which also brings you Physics World.
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A new graphene nanostructure could become the basis for the first ferromagnets made purely from carbon. Known as an asymmetric or “Janus” graphene nanoribbon after the two-faced god in Roman mythology, the opposite edges of this structure have different properties, with one edge taking a zigzag form. Lu Jiong , a researcher at the National University of Singapore (NUS) who co-led the effort to make the structure, explains that it is this zigzag edge that gives rise to the ferromagnetic state, making the structure the first of its kind.
“The work is the first demonstration of the concept of a Janus graphene nanoribbon (JGNR) strand featuring a single ferromagnetic zigzag edge,” Lu says.
Graphene nanostructures with zigzag-shaped edges show much promise for technological applications thanks to their electronic and magnetic properties. Zigzag GNRs (ZGNRs) are especially appealing because the behaviour of their electrons can be tuned from metal-like to semiconducting by adjusting the length or width of the ribbons; modifying the structure of their edges; or doping them with non-carbon atoms. The same techniques can also be used to make such materials magnetic. This versatility means they can be used as building blocks for numerous applications, including quantum and spintronics technologies.
Previously, only two types of symmetric ZGNRs had been synthesized via on-surface chemistry: 6-ZGNR and nitrogen-doped 6-ZGNR, where the “6” refers to the number of carbon rows across the nanoribbon’s width. In the latest work, Lu and co-team leaders Hiroshi Sakaguchi of the University of Kyoto, Japan and Steven Louie at the University of California, Berkeley, US sought to expand this list.
“It has been a long-sought goal to make other forms of zigzag-edge related GNRs with exotic quantum magnetic states for studying new science and developing new applications,” says team member Song Shaotang, the first author of a paper in Nature about the research.
Building on topological classification theory developed in previous research by Louie and colleagues, theorists in the Singapore-Japan-US collaboration predicted that it should be possible to tune the magnetic properties of these structures by making ZGNRs with asymmetric edges. “These nanoribbons have one pristine zigzag edge and another edge decorated with a pattern of topological defects spaced by a certain number m of missing motifs,” Louie explains. “Our experimental team members, using innovative z-shaped precursor molecules for synthesis, were able to make two kinds of such ZGNRs. Both of these have one edge that supports a benzene motif array with a spacing of m = 2 missing benzene rings in between. The other edge is a conventional zigzag edge.”
Crucially, the theory predicted that the magnetic behaviour – ranging from antiferromagnetism to ferrimagnetism to ferromagnetism – of these JGNRs could be controlled by varying the value of m. In particular, says Louie, the configuration of m = 2 is predicted to show ferromagnetism – that is, all electron spins aligned in the same direction – concentrated entirely on the pristine zigzag edge. This behaviour contrasts sharply with that of symmetric ZGNRs, where spin polarization occurs on both edges and the aligned edge spins are antiferromagnetically coupled across the width of the ribbon.
To validate these theoretical predictions, the team synthesized JGNRs on a surface. They then used advanced scanning tunnelling microscope (STM) and atomic force microscope (AFM) measurements to visualize the materials’ exact real-space chemical structure. These measurements also revealed the emergence of exotic magnetic states in the JGNRs synthesized in Lu’s lab at the NUS.
In the past, Sakaguchi explains that GNRs were mainly synthesized using symmetric precursor chemical structures, largely because their asymmetric counterparts were so scarce. One of the challenges in this work, he notes, was to design asymmetric polymeric precursors that could undergo the essential fusion (dehydrogenation) process to form JGNRs. These molecules often orient randomly, so the researchers needed to use additional techniques to align them unidirectionally prior to the polymerization reaction. “Addressing this challenge in the future could allow us to produce JGNRs with a broader range of magnetic properties,” Sakaguchi says.
According to Lu, the team’s research shows that JGNRs could become the first carbon-based spin transport channels to show ferromagnetism. They might even lead to the development of carbon-based ferromagnets, capping off a research effort that began in the 1980s.
However, Lu acknowledges that there is much work to do before these structures find real-world applications. For one, they are not currently very robust when exposed to air. “The next goal,” he says, “is to develop chemical modifications that will enhance the stability of these 1D structures so that they can survive under ambient conditions.”
A further goal, he continues, is to synthesize JGNRs with different values of m, as well as other classes of JGNRs with different types of defective edges. “We will also be exploring the 1D spin physics of these structures and [will] investigate their spin dynamics using techniques such as scanning tunnelling microscopy combined with electron spin resonance, paving the way for their potential applications in quantum technologies.”
The post Two-faced graphene nanoribbons could make the first purely carbon-based ferromagnets appeared first on Physics World.
The Trump administration’s buyout program was extended to civilian employees in agencies with critical space-related missions
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Parallels with aviation and maritime industries offer important insights for managing increasingly congested orbits, according to a Feb. 6 panel of space technology executives at the SmallSat Symposium in Silicon Valley.
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A Defense Department unit is examining how SpaceX’s Starship vehicle could be used to support a broader architecture of in-space refueling.
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The sensor manufacturer alleges the satellite maker broke an agreement and misused Geost's status as a new market entrant to win a Space Development Agency contract before switching to a different supplier.
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