Lifeboat Foundation

The increasing demand for ever-faster information processing has ushered in a new era of research focused on high-speed electronics operating at frequencies nearing terahertz and petahertz regimes. While existing electronic devices predominantly function in the gigahertz range, the forefront of electronics is pushing towards millimeter waves, and the first prototypes of high-speed transistors, hybrid photonic platforms, and terahertz metadevices are starting to bridge the electronic and optical domains.

However, characterizing and diagnosing such devices pose a significant challenge due to the limitations of available diagnostic tools, particularly in terms of speed and spatial resolution. How shall one measure a breakthrough device if it’s the fastest and smallest of its kind?

In response to this challenge, a team of researchers from the University of Konstanz now proposes an innovative solution: They create femtosecond electron pulses in a transmission electron microscope, compress them with infrared laser light to merely 80 femtosecond duration, and synchronize them to the inner fields of a laser-triggered electronic transmission line with the help of a photoconductive switch. Then, using a pump-probe approach, the researchers directly sense the local electromagnetic fields in their electronic devices as a function of space and time.

Diamond is known for its outstanding thermal conductivity. This makes the material ideal for cooling electronic components with high power densities, such as those used in processors, semiconductor lasers or electric vehicles. Researchers at Fraunhofer USA, an independent international affiliate of the Fraunhofer-Gesellschaft, have succeeded in developing wafer-thin nanomembranes from synthetic diamonds that can be integrated into electronic components, thereby reducing the local heat load by up to ten times. This helps to improve the road performance and service life of electric cars and significantly reduces battery charging time.

An increase in power density and the resulting higher heat dissipation in electronic components require new materials. Diamond is known for its high thermal conductivity, which is four to five times higher than that of copper. For this reason, it is a particularly interesting material when it comes to cooling power electronics in electric transportation, photovoltaics or storage systems.

Until now, heat sinks made of copper or aluminum plates have increased the heat-emitting surface of components that produce heat, thus preventing damage due to overheating.

‘Opposites charges attract; like charges repel’ is a fundamental principle of basic physics. But a new study from Oxford University, published in Nature Nanotechnology (“A charge-dependent long-ranged force drives tailored assembly of matter in solution”), has demonstrated that similarly charged particles in solution can, in fact, attract each other over long distances. Just as surprisingly, the team found that the effect is different for positively and negatively charged particles, depending on the solvent.

The study found that negatively charged silica microparticles suspended in water attracted each other to form hexagonally arranged clusters. (Image: Zhang Kang)

Besides overturning long-held beliefs, these results have immediate implications for a range of processes that involve interparticle and intermolecular interactions across various length-scales, including self-assembly, crystallisation, and phase separation.

Cutting-edge research harnesses butterfly mating behaviors to create a groundbreaking visuochemical integration platform. This bio-inspired hardware, merging visual and chemical data, paves the way for advanced multisensory decision-making in artificial intelligence.

Physics has a diversity problem: those with identities outside of the majority “able-bodied, white, cis, and male” face significant barriers to entry. While efforts in the US to level the playing field are beginning to show success, studies continue to find that minority physicists will likely experience some form of bigotry, bias, or barrier during their career that will hamper their chances of success. These inequities and biases range from skewed course structures that favor specific learning styles (see Research News: Restructuring Classes Can Level the Playing Field) to systemic prejudices that hinder some groups from gaining grants (see News Feature: Systemic Racism Reflected in Grant Allocations, Researchers Argue) to unconscious biases that lead to the significant undercitation of minority physicists compared to their white, male counterparts (see News Feature: The Uneven Spread of Citations). All these factors can have serious career consequences, with negative experiences being a key factor driving people to leave the field.

One lesser-studied aspect of identity and how it impacts a person’s experience in physics is neurodivergence—a nonmedical umbrella term used to describe people whose brains process information in way that is different to what is considered normal. Now Geraldine Cochran of Ohio State University and Liam McDermott and Nazeer Mosley, both of Rutgers University, New Jersey, have developed a framework for interpreting the experiences of this group of people [1]. An initial analysis of interviews with three neurodivergent physicists shows that, while this group reports little outright discrimination or violence, structural ableism negatively impacted their time as students. “There are more neurodivergent people entering college than ever before,” McDermott says. “But their needs regularly get overlooked.”

A person who identifies as neurodivergent may have a neurological disorder, such as autism or Tourette’s syndrome; they may have a learning disability, such as dyslexia (which affects language processing) or dyscalculia (which affects number processing); or they could have a mental illness, such as depression or anxiety. For their study, Cochran, McDermott, and Mosley interviewed three physicists who identified as being neurodivergent and who pursued nonacademic careers after completing their undergraduate degrees. All three identified as having attention-deficit hyperactivity disorder (ADHD) and anxiety. Sky (the interviewees were all given pseudonyms) also has depression, Catalina has depression and dyslexia, and Henry has epilepsy. The interviews covered the trio’s undergraduate experiences. Cochran, McDermott, and Mosley then analyzed the trio’s answers using their newly developed “Critical Disability Physics Identity” framework.

Experiments demonstrate some of the unusual features of molecular reactions that occur in the deep cold of interstellar space.

Many common small molecules are formed in interstellar space, and their low temperatures are expected to have profound effects on their chemical reactions because of quantum-mechanical effects that are masked at higher temperatures. Researchers have now demonstrated some of these cold chemistry phenomena—such as the effects of molecular rotation and collision energy on reaction rates—in a reaction between a hydrogen ion and an ammonia molecule in the lab. The results, while intuitively surprising at first glance, can be explained by a careful theoretical analysis of the quantum chemistry.

Measuring reaction rates at low temperatures is useful for testing quantum-chemical theory because in those conditions molecules may occupy only a few well-defined quantum states. Such experiments could also offer insights into chemical processes in the cold clouds of gas in star-forming regions of interstellar space, where many of the simple molecules that make up solar systems are formed. But low-temperature experiments are difficult, especially for charged atoms and molecules (ions), because they are very sensitive to stray electric fields in the environment, which accelerate and heat up the ions.

Researchers have determined the amount of transverse orbital angular momentum that a type of optical vortex carries per photon, an important step for future applications.

From early in his career, Kamal Kesour understood the damaging effects of urban noise and was aware of the instrumentation used to measure and control it. He had lived in big cities, and after his PhD he went to work for an environmental consulting firm that specialized in urban noise. But it wasn’t until later, during a research position at Innovation Maritime in Canada, that he realized marine mammals can experience similarly noisy environments. This noise comes from underwater vibrations generated by shipping vessels transporting goods around the world. Kesour now has a career helping to make maritime transportation vessels less noisy.

Kesour has spent the past few years in Rimouski, Canada, at the Marine Acoustic Research Station (MARS), which lies on the banks of the St. Lawrence Estuary and is jointly led by Innovation Maritime, the Rimouski Institute of Marine Sciences, and engineering consultancy OpDAQ systems. There, he measures ambient underwater noise from ships as they pass on their way to and from the Atlantic Ocean or North America’s Great Lakes. He also conducts on-ship measurements to help pinpoint noise sources and to “fingerprint” the vibrations of individual ships. Physics Magazine caught up with Kesour to learn more about his measurements and their implications for noise pollution produced by the shipping industry.

All interviews are edited for brevity and clarity.

Researchers at the University of Rochester’s Laboratory for Laser Energetics (LLE) have led experiments showcasing an efficient “spark plug” for direct-drive approaches to inertial confinement fusion (ICF). In a pair of studies featured in Nature Physics, the team shares their findings and details the potential for scaling up these methods, aiming for successful fusion in a future facility.

LLE is the largest university-based U.S. Department of Energy program and hosts the OMEGA laser system, which is the largest academic laser in the world but still almost one hundredth the energy of the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in California. With OMEGA, Rochester scientists completed several successful attempts to fire 28 kilojoules of laser energy at small capsules filled with deuterium and tritium fuel, causing the capsules to implode and produce a plasma hot enough to initiate fusion reactions between the fuel nuclei. The experiments caused fusion reactions that produced more energy than the amount of energy in the central hot plasma.

The OMEGA experiments use direct laser illumination of the capsule and differ from the indirect drive approach used on the NIF. When using the indirect drive approach, the laser light is converted into X-rays that in turn drive the capsule implosion. The NIF used indirect drive to irradiate a capsule with X-rays using about 2,000 kilojoules of laser energy. This led to a 2022 breakthrough at NIF in achieving fusion ignition —a fusion reaction that creates a net gain of energy from the target.