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New stunning images show the James Webb Space Telescope’s fully aligned optics

NASA and its partners have announced that the optics alignment on the $10bn James Webb Space Telescope (JWST) is now complete – marking another significant step towards a fully functioning infrared observatory.

Yesterday, the space agency announced that the observatory is now capable of capturing crisp, well-focused images with each of its onboard science instruments – the Near Infrared Spectrograph (NIRSpec), the Near-Infrared Camera (NIRCAM), the Mid-Infrared Instrument (MIRI) and the Near Infrared Imager and Slitless Spectrograph (NIRISS).

For the optics test, JWST pointed at a part of the Large Magellanic Cloud – a small satellite galaxy of the Milky Way – that provided a dense field of hundreds of thousands of stars. As well as images from the four instruments, the release also contains pictures from the Fine Guidance Sensor, which is used to track guide stars to point the observatory accurately and precisely.

NASA says that the image quality to all instruments is “diffraction-limited”, which means that the detail acquired is “as good as physically possible given the size of the telescope”.

“These remarkable test images from a successfully aligned telescope demonstrate what people across countries and continents can achieve when there is a bold scientific vision to explore the universe,” notes Lee Feinberg, optical telescope element manager for the JWST who is based at NASA’s Goddard Space Flight Center.

The next and final series of preparations towards a fully commissioned observatory is science instrument commissioning. This will take about two months to complete before scientific operations begin, which is expected in late June.

The JWST is a collaboration between NASA, the European Space Agency and the Canadian Space Agency.

Negative capacitance could make transistors more energy efficient

By exploiting a curious effect called negative capacitance, researchers have designed a transistor that requires a gate voltage about 30% lower than conventional designs. Led by Sayeef Salahuddin at the University of California, Berkeley, the team based their design around an ultrathin superlattice heterostructure, containing alternating layers of ferroelectric and antiferroelectric materials. The team says that its superlattice could be easily integrated into existing transistor designs, reducing their energy requirements.

As modern computers grow ever more powerful, the energy they consume is also growing with seemingly no end in sight. Slowing this trend will require fundamental changes to traditional transistor designs.

Metal-oxide-semiconductor field-effect transistors (MOSFETs) are ubiquitous in computers and other electronics. They comprise a silicon semiconductor channel through which current can flow between two electrodes. The current flows past a third electrode called the gate, which is separated from the semiconductor channel by an insulating oxide layer. The gate electrode acts like one plate of a capacitor and by varying the voltage applied to the gate, the electronic properties of the silicon can be adjusted. The result is that the current flowing through the channel can be switched on and off.

Opposite effect

In their study, Salahuddin’s team sought to improve this design by exploiting negative capacitance. This an effect that Salahuddin first predicted in 2008 and demonstrated experimentally in 2011. It occurs when a decrease in the voltage across a capacitor results in an increase in the charge stored in the device – the opposite of what happens in conventional capacitors.

Negative capacitance arises in ferroelectric materials, whose spontaneous electric polarization can be reoriented with the application of an external electric field. To create negative capacitance, an insulating dielectric material is paired with a ferroelectric material – significantly amplifying the amount of charge that accumulates in a ferroelectric material at a given voltage.

Salahuddin and colleagues have now demonstrated the effect in a new, ultra-thin superlattice material. It comprises alternating, atom-thick layers of the strongly dielectric, ferroelectric material, hafnium dioxide and the antiferroelectric compound zirconium dioxide – which displays zero spontaneous polarization.

Performance matching

To test their material’s capabilities, the researchers deposited a film of the superlattice just 2 nm thick onto a thin glass layer – separating from it from a silicon layer. In the resulting MOSFET, the team found that the gate voltage could be reduced by about 30%, which reduces the energy consumption of the device. The resulting device was able to match the performance of existing transistor designs.

Since hafnium dioxide is already widely used in combination with silicon dioxide to form the insulating layers in MOSFETs, this design is highly compatible with existing manufacturing processes. As a result, Salahuddin and colleagues hope that their material could substantially reduce the amount of energy consumed by modern computers, without sacrificing their speed, performance, or small size.

The research is described in Nature.

Radiation detectors could help find ancient buildings and dinosaur bones

In this episode of the Physics World Weekly podcast, Victoria Robinson and Stuart Black at the University of Reading explain how gamma-ray spectrometers have been used for the first time to locate ancient underground structures. The technique is normally used to identify radioactive contamination on nuclear sites and the duo describe how was adapted for use by archaeologists at Roman Silchester in southern England. They also point out other uses, including helping in the search for dinosaur bones.

We also look at what is new in physics, including how X-ray astronomers are giving biomedical imaging a boost.

Super-resolution microscopy reveals coronavirus-replicating machinery

The virus-replicating machinery of the SARS-Cov-2 virus and the ribonucleic acid (RNA) molecules it produces as it replicates are located in physically distinct areas of an infected cell. This observation, made by researchers at Stanford University in the US using a new multicolour super-resolution microscopy imaging technique, provides fresh insights into the life cycle of coronaviruses and could aid the development of new therapeutics to fight them.

The coronavirus responsible for the COVID-19 pandemic is one of seven coronaviruses that can infect humans, and the third within 20 years to cause life-threatening disease. To develop improved treatments to fight this and other such viruses, researchers need to better understand the biology of the coronavirus’ genome RNA, or gRNA, during infection, as this RNA contains all the “blueprints” required for making the proteins needed for the virus to replicate.

A team led by William Moerner and Stanley Qi at Stanford has now studied coronavirus infection at the nanoscale using high-throughput confocal and super-resolution microscopy. The researchers used a less harmful human coronavirus, HCoV-229E, as their model, because it is similar to SARS-Cov-2 in that it contains an envelope studded with protein spikes surrounding a strand of gRNA. These proteins include those that make gRNA copies and those that assemble into the “packaging” that wraps around the gRNA to make new viruses.

Differently coloured fluorescent tags

In their study, Moerner, Qi and colleagues focused on gRNA and another type of RNA, double-stranded RNA (dsRNA), which makes new copies of the virus. They began by labelling the gRNA and dsRNA with differently coloured fluorescent tags – magenta for the gRNA and green for the dsRNA – so that they could study where the two types of RNA migrated in a cell. The technique they used to do this, confocal fluorescence microscopy, is good at recording light emitted from the fluorescent labels. However, its spatial resolution is limited to imaging structures 250 nm in size or bigger. This is a problem because coronaviruses are half this size, and the proteins and RNA they contain are smaller still, at 50 nm and 10 nm or less. The result is that the images obtained are blurry and cannot distinguish between the different biological structures, let alone pinpoint where they are located in a cell.

To overcome this problem, the researchers turned to super-resolution fluorescence microscopy, which brings these structures into sharper focus, allowing objects as small as 10 nm across to be imaged. This is well below the optical diffraction limit. Using this technique, Moerner, Qi and colleagues report that they observed an “amazing galaxy” of structures, including a dark “sky” of non-overlapping bright magenta clusters and green stars.

The new observations are in stark contrast to the images obtained using confocal microscopy, which showed blurry white clouds in addition to spots of green and magenta, suggesting that the dsRNA and gRNA could be in the same areas in the cells and possibly even enveloped together. The images from the more complex multi-colour super-resolution fluorescence technique contradict this hypothesis, revealing that the different types of RNA are physically separated in the cell.

Temporary dsRNA storage centres

Further experiments confirmed that the viral replication occurs in a part of the cell known as the endoplasmic reticulum, something that researchers already knew, and that the gRNA formed then “buds off” into the cell to become packaged into a fully-formed virus. However, in contrast to previous studies, Moerner, Qi and colleagues observed that as well as being in the endoplasmic reticulum, the dsRNA is also found in large spheres that can be up to 450 nm in size. These spheres do not contain any gRNA.

The researchers say that these dsRNA spheres could serve as temporary dsRNA storage centres while new viruses are “being packaged and shipped out”. While they are as yet unsure what makes the virus produce these temporary storage sites, they hope their technique could shed more light on this puzzle in the future. What is more, discovering where viral infection takes place could lead to better treatments to fight these pathogens.

“While the optical method we developed is not completely new, combining it with specific labelling of the important virus RNA components is new, to our knowledge,” Moerner tells Physics World. “The technique could be applied to many other coronaviruses, including new variants, and to monitor how they react to various drug treatments. Indeed, the Stanford team hopes to do just this in future work.”

The present study is detailed in Cell Reports Methods.

Physics is something that girls fancy

Physics opens doors to extraordinary careers in research, engineering and industry. It teaches people to think critically, to solve complex problems and to design solutions to the world’s biggest challenges. But not all young people are welcomed to physics equally. Some are discouraged by out-of-date opinions and widespread misconceptions about what physics is, and some are put off by lazy stereotypes and bias.

The under-representation of women in physics doesn’t seem to bother Katharine Birbalsingh, head teacher of the Michaela Community School in London and chair of the UK government’s social mobility commission. When delivering “evidence” yesterday to the House of Commons Science and Technology Select Committee on Diversity and Inclusion in STEM, Birbalsingh explained that “Physics isn’t something that girls tend to fancy. They don’t want to do it. They don’t like it…There’s a lot of hard maths in there that they don’t want to do.”

When questioned by the committee why that might be – given that girls outperform boys at GCSE and A-level maths – Birbalsingh explained that she didn’t mind. “We’re certainly not out there campaigning for more girls to do physics,” she added. “I wouldn’t do that, and I don’t want to do that.”

While her decision to present parliament with uninformed guesses as opposed to evidence-based insight surprised me, her tired rhetoric is nothing new. Society has been telling women that they’re not cut out for physics and advanced maths for centuries.  In the UK, only 23% of physics A-level students are women. In the Michaela Community School, which Birbalsingh founded, that number is even lower: with only 16% of the physics A-level cohort being young women.

Physics for all

Birbalsingh – who was awarded a CBE in 2020 for services to education – is no stranger to controversial opinions. In 2019 she said that parents should always “back the teacher”, irrespective of how they are treating children. Shortly after the UK rapper Stormzy launched a scholarship for Black British students at the University of Cambridge in 2018, Birbalsingh criticized him for his lyrics that “encourage Black self-hatred”.

To really shift the dial on who studies physics, we need a whole school approach to equity and equality

Her baseless opinions on physics are equal parts absurd and dangerous. The Institute of Physics has studied the under-representation of women in physics for decades. Its longitudinal studies, reports and consultations have shown that there is no intrinsic difference in girls’ preference or ability in physics. Young people opt out of physics because of limited access to exceptional teachers, poor career advice, how they are treated or what they are told by people whom they trust.

Perpetuating the myth that physics is done by lone, nerdy geniuses who work in isolation doesn’t help, either. Sexist language, a school environment that reinforces gender stereotypes, and pastoral support that doesn’t encourage girls to develop self-confidence and resilience present additional challenges.

When people with trusted opinions offer advice that is fuelled by their own biases and misconceptions, they limit young people’s aspirations. For far too long, opinions like Birbalsingh’s have made generations of innovative and talented young women believe they won’t be successful physicists and engineers.

To really shift the dial on who studies physics, we need a whole school approach to equity and equality. All staff – including senior leaders and governors – need to be trained on unconscious biases and gender stereotypes. Although this may not align with the ultra-strict rules of Michaela, students need to be empowered to join this fight for equality, too. Physics teachers should work to introduce content in an inclusive and accessible way – ensuring that their resources and examples are diverse, contemporary and exciting.

Thankfully, plenty of scientists, educators and schools are campaigning for more girls to do physics. These efforts are partly driven by the need to train more young people with physics-based skills and ultimately make the UK economically competitive, and partly by ambitions to build a fairer and equal world.

Challenging outdated stereotypes and improving school culture doesn’t only benefit girls. You don’t need to be good at “really hard maths” to appreciate that and by tackling inequalities in the school system you benefit all young people – and society as a whole.

Quantum Machines presents Quantum Orchestration Platform at APS March Meeting 2022

“Our vision at Quantum Machines is to accelerate the realisation of useful quantum computers by providing researchers and engineers with unique technology that allows them to extract the most out of their quantum devices.” So says Yonatan Cohen, co-founder and chief technology officer of Quantum Machines, in this video filmed at the 2022 March meeting of the American Physical Society in Chicago.

As Itamar Sivan – the company’s co-founder and chief executive – goes on to explain, Quantum Machines has the ambitious goal of letting experimentalists and engineers to “run the most advanced experiments and algorithms they could dream of right out of the box”. Indeed, Sivan claims that its quantum-control system, which integrates hardware and software, can let researchers “do in days what used to take years”.

Machine learning detects seismic activity in noisy cities

A machine-learning algorithm that filters seismic data to remove noise from human activity has been developed by researchers in the US and China. Called the UrbanDenoiser, the algorithm is trained using noise signals found an urban environment as well as earthquake signals detected in a more rural location.

Owing to their high population densities and heavily built-up environments, cities are especially vulnerable to damage from earthquakes. This risk presents the need for intensive seismic monitoring in urban areas lying close to the boundaries between tectonic plates. This can be difficult, however, because human activities such as traffic and construction also create seismic signals in detectors.

Human noise is a particular problem for seismic monitoring in the Los Angeles metropolitan area. With a population of over 18 million, the megacity lies on a network of fault lines, which form the boundary between the Pacific and North American plates.

Far from the madding crowd

To address the noise issue, Lei Yang at Stanford University and colleagues developed the UrbanDenoiser, which can be trained to recognize human-related noise, and filter it out of natural seismic data. To train their model, the researchers collected 80,000 recordings of seismic noise in the Long Beach area of Los Angeles when earthquake activity was relatively low. Simultaneously, they collected over 33,000 low-noise earthquake signals in San Jacinto – which is about 130 km from Long Beach and outside of the main urban area of Los Angeles.

The team then generated artificial seismic waveforms with different levels of urban noise, by repeatedly combining the San Jacinto training set with randomly selected samples from the Long Beach training set; and then randomly shifting the resulting waveforms.

Once trained to recognize how urban earthquake signals are masked by human seismic noise, the UrbanDenoiser was used to examine data taken at five stations during an earthquake in 2014 that struck La Habra in the Los Angeles urban area. By filtering out human-related noise, the algorithm detected 10% more seismic events associated with the earthquake than the Quake Template Matching catalogue – currently the most comprehensive earthquake catalogue available for southern California.

UrbanDenoiser still has some issues to iron out, and the researchers now aim to reduce rates of false positives and negatives in their future research. With the ability to improve the quality of earthquake signals collected in urban environments, they hope that the algorithm will allow authorities in earthquake-prone regions to monitor seismic activity more accurately – helping them to better protect vulnerable urban infrastructure.

The research is described in Science Advances.

Bluefors presents new cooling platform KIDE at APS March Meeting 2022

Spun off from the low-temperature lab at Aalto University in Finland, Bluefors is a firm that specializes in cryogen-free, dilution refrigerator measurement systems. Based in Helsinki, the company presented its new KIDE cooling platform at the 2022 March meeting of the American Physical Society in Chicago.

In this video filmed at the meeting, Bluefors’ chief technology officer David Gunnarsson outlines the benefits to users of the KIDE cryogenic system, which the company developed in response to the needs of researchers working in quantum computing. Based on the Finnish word for “snowflake”, KIDE is so named because the cooling platform is hexagonal in shape. With a prototype being developed this year, Bluefors envisages a product launch in 2023.

Back to business: the American Physical Society’s 2022 March meeting takes place in Chicago

“We’re back. This is amazing!” So says David Cooke from the American Physical Society (APS) on the return of the APS March meeting, which took place in-person this year for the first time since 2019 following the disruptions caused by the COVID-19 pandemic.

Cooke is especially pleased with the meeting’s exhibition, which featured displays from hi-tech firms as well as poster sessions, workshops and the all-important attendee lounges. “The meeting revolves around the exhibit hall”, says Cooke, who is already looking forward to the 2023 APS March meeting, which will take place in Las Vegas. “We really hope to see you there,” he says. “It wouldn’t be the same without you!”

Atomic quantum processors make their debut

The first quantum processors that use neutral atoms as qubits have been produced independently by two US-based groups. The result is a milestone because atomic quantum computers may be easier to scale up than devices based on superconducting circuits or trapped ions – the two technologies that have dominated so far.

The first qubits were demonstrated in 1995 in trapped ions by David Wineland, Chris Monroe and colleagues at NIST in Boulder, Colorado, US. More recently, companies such as Google and IBM have produced computers using solid-state superconducting qubits, with the 127-qubit IBM Eagle processor currently regarded as the most powerful. However, as quantum computers have grown ever larger, this platform has encountered problems. Superconducting qubits must be constructed individually, making it near-impossible to fabricate identical copies. This compromises the “gate fidelity” (the probability of the output being correct). Moreover, each qubit must be cooled close to absolute zero – a task that becomes ever more difficult as qubit numbers increase.

Other companies – including Monroe’s own start-up, IonQ – have turned to trapped ions as an alternative. In September 2020, the industrial giant Honeywell announced that its trapped ion computer had achieved a record “quantum volume” – a measure of the computer’s capabilities and error rates. Trapped-ion computers have the advantage that each ion is guaranteed indistinguishable by the laws of quantum mechanics, while ions in a vacuum are relatively easy to isolate from thermal noise. The problem is that “ions are strongly interacting and you need to move them around with electric fields,” says Dolev Bluvstein of Harvard University in the US. “This is pretty hard in practice.”

In 2016, Mikhail Lukin of Harvard, together with colleagues at the Massachusetts Institute of Technology (MIT) and, independently, researchers at the Institut d’Optique in Paris, unveiled yet a third platform, storing quantum information in neutral atoms that they manipulated using optical tweezers. By using a laser to excite the atoms to a highly ionized Rydberg state, the researchers were able to entangle them with other atoms, allowing gate operations to be performed before the output of the gate was stored stably once again. However, nobody has previously demonstrated a full quantum circuit using neutral atoms.

Hyperfine states

In the latest research, both teams stored quantum information in the hyperfine states of alkali atoms: rubidium for Bluvstein and colleagues led by Lukin, and caesium for a team led by Mark Saffman of the University of Wisconsin-Madison, together with scientists from the quantum firms ColdQuanta and Riverlane. Bluvstein explains that these hyperfine states have several advantages. “If you have two atoms in a hyperfine state next to each other, because they’re so robust they don’t do anything,” he says. “So if we want to entangle two atoms on demand, we simultaneously try to excite both of them to the Rydberg state. These Rydberg states are huge and really strongly interacting, and that allows us to entangle the atoms really quickly. Now we come back down to the hyperfine state, safe and sound, where the entangled atoms are robust to the optical tweezer.”

The Harvard-MIT group used this robustness to physically separate the entangled atoms without causing them to decohere (that is, to lose their quantum information). When each atom arrives at its destination, another pulse from the laser entangles it with the next atom. This enables the group to perform non-local quantum gate operations without needing photonic or atomic links to move entanglement around the circuit.

The researchers used this protocol to execute several programs. Notably, they prepared a “logical qubit” made up of seven physical qubits that could encode information in an error-resistant fashion. Bluvstein notes that entangling multiple logical qubits would be much simpler in his team’s system than in alternatives that use static qubits. “There’s a lot of different tricks called braiding or lattice surgery that people work to entangle logical qubits,” he explains, “but once you have the movement of atoms, and once you can interlace them, it’s very simple: all you have to do is make two of them independently, move each group of qubits, interlace it with the other group, pulse the Rydberg laser once and do a gate between them.” This flexibility, Bluvstein says, should allow researchers to perform quantum error correction and entanglement between logical qubits “in a way that simply is not possible with superconducting qubits or trapped ions”.

Precision control

The Wisconsin group took a different tack. Instead of physically moving their atoms, they used precision-controlled laser light to manipulate the atoms’ Rydberg excitations and transfer entanglement around the lattice. “Imagine you have three qubits in a line,” Saffman explains. “I’m going to take two laser beam spots and illuminate the left-most one and the centre one. They get excited to the Rydberg state, they interact, they become entangled.” The next step, Saffman continues, is to move the laser beams to illuminate the centre atom and the right one that was previously inactive and excite both to the Rydberg state. In this fashion, he concludes, “the laser beams are controlling the gate operations but the actual linking mechanisms are the atomic Rydberg interactions”.

Saffman’s group demonstrated the power of their scheme by producing six-atom states known as Greenberger-Horne-Zeilinger states, which are sometimes termed Schrödinger cat states because they have the strongest possible non-local correlations of all multi-particle quantum states. The Wisconsin team also showed that their system could act as a quantum simulator by performing various quantum phase estimation problems, such as estimating the energy of a hydrogen molecule.

By keeping the atoms static, the Wisconsin team could link sequential gate operations more quickly than the Harvard-MIT group, albeit with some loss in flexibility. However, the Harvard-MIT group’s approach allowed them to perform multiple gate operations in parallel, thereby achieving a clock speed higher than the Wisconsin group. “Highly parallel operations with arbitrary non-local connectivity are central for building large scale quantum machines and this is what our work demonstrates for the first time,” explains Lukin.  “Ultimately I think these two approaches may well be combined into a single, more powerful system, but right now they’re two fascinating examples of the multiplicity of approaches one can take,” concludes Saffman.

Hannah Williams, an atomic physicist at Durham University in the UK who was not involved in the research, says that both groups have shown “the ability of the platform and its promise for quantum computing by demonstrating iconic quantum algorithms, be that error correction or phase estimation”. However, she cautions that the gate fidelities need to be improved and the number of atoms increased before the system is truly competitive. “The selling point of neutral atomic systems is always that they should be really easy to scale, and the demonstrations were on at most 24 qubits,” she says.

Monroe agrees, adding that he believes the two challenges are connected. “It doesn’t really matter how many qubits you have,” he says. “If you can only run at 95% fidelity, you can only link together 20 or so operations.” He also notes that gate fidelities in atomic systems are currently far too low to benefit from the quantum error correction code demonstrated by Lukin’s group. Nevertheless, he says the groups are “doing the right thing”, adding that atomic qubits have the potential to hit 99.9% fidelity without error correction. “We’re already doing that with trapped ions, and though the neutrals are behind, I don’t have any doubt that they will eventually get there and derive benefit from these very efficient codes,” Monroe concludes.

Both papers are published in Nature.

  • This article was amended on 4/5/22 to clarify the difference between the speed of sequential gate operations and the speed of executing the algorithm.
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