Daily Archives: September 8, 2022

Physicists invent intelligent quantum sensor of light wave properties

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Typically, when you want to characterize a wave of light, you have to use different instruments to gather information, such as the intensity, wavelength and polarization state of the light. Those instruments are bulky and can occupy a significant area on an optical table,” said Dr. Fan Zhang, a corresponding author of the study and associate professor of physics in the School of Natural Sciences and Mathematics.

“Now we have a single device—just a tiny and thin chip—that can determine all these properties simultaneously in a very short time,” he said.

The device exploits the unique physical properties of a novel family of two-dimensional materials called moiré metamaterials. Zhang, a , published a review article on these materials Feb. 2 in Nature.

The 2D materials have periodic structures and are atomically thin. If two layers of such a material are overlaid with a small rotational twist, a moiré pattern with an emergent, orders-of-magnitude larger periodicity can form. The resulting moiré metamaterial yields that differ significantly from those exhibited by a single layer alone or by two naturally aligned layers.

The sensing device that Zhang and his colleagues chose to demonstrate their new idea incorporates two layers of relatively twisted, naturally occurring bilayer graphene, for a total of four atomic layers.

“The moiré metamaterial exhibits what’s called a bulk photovoltaic effect, which is unusual,” said Patrick Cheung, a physics doctoral student at UT Dallas and co-lead author of the study. “Normally, you have to apply a voltage bias to produce any current in a material. But here, there is no bias at all; we simply shine a light on the moiré metamaterial, and the light generates a current via this bulk photovoltaic effect. Both the magnitude and phase of the photovoltage are strongly dependent on the , wavelength and polarization state.”

By tuning the moiré metamaterial, the photovoltage generated by a given incoming light wave creates a 2D map that is unique to that wave—like a fingerprint—and from which the wave’s properties might be inferred, although doing so is challenging, Zhang said.

Researchers in Dr. Fengnian Xia’s lab at Yale University, who constructed and tested the device, placed two , or gates, on top and underneath the moiré metamaterial. The two gates allowed the researchers to tune the quantum geometric properties of the material to encode the infrared light waves’ properties into “fingerprints.”

The team then used a —an artificial intelligence algorithm that is widely used for image recognition—to decode the fingerprints.

“We start with light for which we know the intensity, wavelength and polarization, shine it through the device and tune it in different ways to generate different fingerprints,” Cheung said. “After training the with a data set of about 10,000 examples, the network is able to recognize the patterns associated with these fingerprints. Once it learns enough, it can characterize an unknown .”

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Source: Physicists invent intelligent quantum sensor of light waves

Evusheld COVID Protection for Immunocompromised People

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If you couldn’t get a COVID vaccine, or if you got it but are in the group of people who likely aren’t as well protected, you can get Evusheld for an extra layer of protection.

What is Evusheld?

Evusheld is considered “pre-exposure prophylaxis” for COVID, and is available for people who are moderately to severely immunocompromised. The CDC has guidelines about Evusheld here. Evusheld is given every 6 months.

The treatment consists of two injections of monoclonal antibodies, tixagevimab and cilgavimab. In other words, instead of triggering your body to produce its own antibodies, you’re being given some ready-made antibodies. You should still also get your COVID vaccine, if you’re able to.

Who can get Evusheld?

Evusheld is for people who are moderately or severely immunocompromised or who are unable to be fully vaccinated with one of the regular COVID vaccines (for example, if you had an allergic reaction to your first dose or if you know you are allergic to a component of the vaccine). You also need to be at least 12 years old and weigh at least 88 pounds.

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Source: What Is Evusheld? COVID Protection for Immunocompromised People

The EU’s AI Act could have a chilling effect on open source efforts, experts warn

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The nonpartisan think tank Brookings this week published a piece decrying the bloc’s regulation of open source AI, arguing it would create legal liability for general-purpose AI systems while simultaneously undermining their development. Under the EU’s draft AI Act, open source developers would have to adhere to guidelines for risk management, data governance, technical documentation and transparency, as well as standards of accuracy and cybersecurity.

If a company were to deploy an open source AI system that led to some disastrous outcome, the author asserts, it’s not inconceivable the company could attempt to deflect responsibility by suing the open source developers on which they built their product.

“This could further concentrate power over the future of AI in large technology companies and prevent research that is critical to the public’s understanding of AI,” Alex Engler, the analyst at Brookings who published the piece, wrote. “In the end, the [E.U.’s] attempt to regulate open-source could create a convoluted set of requirements that endangers open-source AI contributors, likely without improving use of general-purpose AI.”

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In a recent example, Stable Diffusion, an open source AI system that generates images from text prompts, was released with a license prohibiting certain types of content. But it quickly found an audience within communities that use such AI tools to create pornographic deepfakes of celebrities.

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“The road to regulation hell is paved with the EU’s good intentions,” Etzioni said. “Open source developers should not be subject to the same burden as those developing commercial software. It should always be the case that free software can be provided ‘as is’ — consider the case of a single student developing an AI capability; they cannot afford to comply with EU regulations and may be forced not to distribute their software, thereby having a chilling effect on academic progress and on reproducibility of scientific results.”

Instead of seeking to regulate AI technologies broadly, EU regulators should focus on specific applications of AI, Etzioni argues. “There is too much uncertainty and rapid change in AI for the slow-moving regulatory process to be effective,” he said. “Instead, AI applications such as autonomous vehicles, bots, or toys should be the subject of regulation.”

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Source: The EU’s AI Act could have a chilling effect on open source efforts, experts warn | TechCrunch

Edit 14/9/22: Willy Tadema has been discussing this with the NL.gov people and points out that Axel Voss has introduced exemptions into the act:

Last week, the Legal Affairs committee in the European Parliament adopted my opinion on the #AIAct with strong support. 17 votes in favor, one against.

Focusing on 10 key areas within the competence of the JURI committee, we send a strong signal to the lead committees, LIBE and IMCO while also presenting new ideas for the political debate on #AI.

On the scope (Art. 2), we introduce three new exemptions.
– On research, testing, development to promote innovation in AI,
– On Business to Business (B2B) to avoid regulating non-risky industrial applications,
– On open-source until its commercialization to support small market players.

We also adjusted the responsibilities of providers (Art. 16) as well as users (Art. 29) as regards their supply chain. In addition, we specified under what circumstances those responsibilities might shift to another actor (Art. 23a) and we tried to integrate general purpose AI into the AI Act.

The JURI committee also transformed the AI Board into a powerful EU body with own legal personality and strong involvement of stakeholders which would help to better coordinate among Member States and to keep AI Act up to date.

As usual, I have to thank Kai Zenner for his tireless work and the great result!

Hydrogen could be harvested from thin air in the desert

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To avoid taking water from an already strained local supply, a team led by Gang Kevin Li, senior lecturer at the University of Melbourne, Australia, has built a system which extracts water from airborne vapor using a hygroscopic electrolyte, in this case sulfuric acid. The approach then uses solar-generated electricity to split the water into hydrogen and oxygen.

The team proved it could operate at a relative humidity of about 4 percent, well below that of most deserts. On a warm sunny day, the meter-square unit was able to produce 3.7m3 of hydrogen.

“Hydrogen is the ultimate clean energy,” the paper, published in Nature Communications, said. “Despite being the most abundant element in the universe, hydrogen exists on the earth mainly in compounds like water. H2 produced by water electrolysis using renewable energy, namely, green hydrogen, represents the most promising energy carrier of the low-carbon economy. H2 can also be used as a medium of energy storage for intermittent energies such as solar, wind, and tidal.”

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Source: Hydrogen could be harvested from thin air in the desert • The Register

Korean nuclear fusion tokamak reactor achieves 100 million°C for 30 seconds

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A nuclear fusion reaction has lasted for 30 seconds at temperatures in excess of 100 million°C. While the duration and temperature alone aren’t records, the simultaneous achievement of heat and stability brings us a step closer to a viable fusion reactor – as long as the technique used can be scaled up.

Most scientists agree that viable fusion power is still decades away, but the incremental advances in understanding and results keep coming. An experiment conducted in 2021 created a reaction energetic enough to be self-sustaining, conceptual designs for a commercial reactor are being drawn up, while work continues on the large ITER experimental fusion reactor in France.

Now Yong-Su Na at Seoul National University in South Korea and his colleagues have succeeded in running a reaction at the extremely high temperatures that will be required for a viable reactor, and keeping the hot, ionised state of matter that is created within the device stable for 30 seconds.

Controlling this so-called plasma is vital. If it touches the walls of the reactor, it rapidly cools, stifling the reaction and causing significant damage to the chamber that holds it. Researchers normally use various shapes of magnetic fields to contain the plasma – some use an edge transport barrier (ETB), which sculpts plasma with a sharp cut-off in pressure near to the reactor wall, a state that stops heat and plasma escaping. Others use an internal transport barrier (ITB) that creates higher pressure nearer the centre of the plasma. But both can create instability.

Na’s team used a modified ITB technique at the Korea Superconducting Tokamak Advanced Research (KSTAR) device, achieving a much lower plasma density. Their approach seems to boost temperatures at the core of the plasma and lower them at the edge, which will probably extend the lifespan of reactor components.

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Source: Korean nuclear fusion reactor achieves 100 million°C for 30 seconds | New Scientist