Whether bismuth is part of a class of materials highly suitable for quantum computing and spintronics was a long‑standing issue. Kobe University research has now revealed that the true nature of bismuth was masked by its surface, and in doing so uncovered a new phenomenon relevant to all such materials.
The team have published their results in a letter in the journal Physical Review B.
There is a class of materials that are insulators in their bulk, but robustly conductive at their surface. As this conductivity does not suffer from defects or impurities, such “topological materials,” as they are called, are expected to be highly suitable for use in quantum computers, spintronics and other advanced electronic applications.
As searches for the leading dark matter candidates—weakly interacting massive particles, axions, and primordial black holes—continue to deliver null results, the door opens on the exploration of more exotic alternatives. Guanming Liang and Robert Caldwell of Dartmouth College in New Hampshire have now proposed a dark matter candidate that is analogous with a superconducting state [1]. Their proposal involves interacting fermions that could exist in a condensate similar to that formed by Cooper pairs in the Bardeen-Cooper-Schrieffer theory of superconductivity.
The novel fermions considered by Liang and Caldwell emerge in the Nambu–Jona-Lasinio model, which can be regarded as a low-energy approximation of the quantum chromodynamics theory that describes the strong interaction. The duo considers a scenario where, in the early Universe, the fermions behave like radiation, reaching thermal equilibrium with standard photons. As the Universe expands and the temperature drops below a certain threshold, however, the fermions undergo a phase transition that leads them to pair up and form a massive condensate.
The proposed scenario has several appealing features, say Liang and Caldwell. The fermions’ behavior would be consistent with that of the cold dark matter considered by the current standard model of cosmology. Further, the scenario implies a slight imbalance between fermions with different chiralities (left-and right-handed). Such an imbalance might be related to the yet-to-be-explained matter–antimatter asymmetry seen in the Universe. What’s more, the model predicts that the fermions obey a time-dependent equation of state that would produce unique, potentially observable signatures in the cosmic microwave background (CMB) radiation. The researchers suggest that next-generation CMB measurements—by the Simons Observatory and by so-called stage 4 CMB telescopes—might reach sufficient precision to vet their idea.
Light is all around us, essential for one of our primary senses (sight) as well as life on Earth itself. It underpins many technologies that affect our daily lives, including energy harvesting with solar cells, light-emitting-diode (LED) displays and telecommunications through fiber optic networks.
The smartphone is a great example of the power of light. Inside the box, its electronic functionality works because of quantum mechanics. The front screen is an entirely photonic device: liquid crystals controlling light. The back too: white light-emitting diodes for a flash, and lenses to capture images.
We use the word photonics, and sometimes optics, to capture the harnessing of light for new applications and technologies. Their importance in modern life is celebrated every year on 16 May with the International Day of Light.
Quantum entanglement—a connection between particles that produces correlations beyond what is classically possible—will be the backbone of future quantum technologies, including secure communication, cloud quantum computing, and distributed sensing. But entanglement is fragile; noise from the environment degrades entangled states over time, leaving scientists searching for methods to improve the fidelity of noisy entangled states.
Now, researchers at the University of Chicago Pritzker School of Molecular Engineering (UChicago PME), University of Illinois Urbana-Champaign, and Microsoft have shown that it is fundamentally impossible to design a single one-size-fits-all protocol to counteract that noise.
“In quantum information, we often hope for a protocol that works in all scenarios—a kind of cure-all,” said Asst. Prof. Tian Zhong, senior author of the new work published in Physical Review Letters. “This result shows that when it comes to purifying entanglement, that’s simply too good to be true.”
A new study from the University of Portsmouth has outlined a possible way to improve how we distinguish between two closely spaced light sources, an issue that has long challenged classical imaging systems.
The approach, published in Physical Review Applied, uses principles from quantum physics to estimate small separations between light-emitting objects, with potential future applications in fields like microscopy, astronomy, and remote sensing.
The research suggests that a relatively simple quantum set-up could be used to extract spatial information that is traditionally limited by the so-called Rayleigh criterion—a rule dating back over a century that defines the limits of classical resolution.
Researchers have shown that abstract mathematical functions from the frontiers of theoretical physics have a real-world use in modeling gravitational waves
We know that all the other forces governed by quantum mechanics are transmitted by indivisible particles: photons for the electromagnetic force, which governs light and the basic chemistry of matter; gluons for the strong force, which sticks together protons and neutrons inside atoms; and W and Z bosons for the weak force, which enables certain particles to radioactively decay. If gravity has the same underlying theory as these forces, it should also be carried by its own particle: a graviton. Now researchers, including Claudia Du Rham at Imperial in London, are in the hunt for these mysterious and vanishingly weak particles. – Learn more ➤ https://www.newscientist.com/article/.… ➤ https://bit.ly/NSYTSUBS Get more from New Scientist: Official website: https://bit.ly/NSYTHP Facebook: https://bit.ly/NSYTFB Twitter: https://bit.ly/NSYTTW Instagram: https://bit.ly/NSYTINSTA LinkedIn: https://bit.ly/NSYTLIN About New Scientist: New Scientist was founded in 1956 for “all those interested in scientific discovery and its social consequences”. Today our website, videos, newsletters, app, podcast and print magazine cover the world’s most important, exciting and entertaining science news as well as asking the big-picture questions about life, the universe, and what it means to be human. New Scientist https://www.newscientist.com/
About New Scientist: New Scientist was founded in 1956 for “all those interested in scientific discovery and its social consequences”. Today our website, videos, newsletters, app, podcast and print magazine cover the world’s most important, exciting and entertaining science news as well as asking the big-picture questions about life, the universe, and what it means to be human.
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Correction to the screen text at 05:04: It’s in the range of microgram. What I say is correct, the text isn’t. Sorry about that.
This video comes with a quiz which you can take here: https://quizwithit.com/start_thequiz/.… are one of the most sought-after particles in physics. They could help physicists combine quantum physics with gravity to create a theory of “quantum gravity.” We thought until recently they were for all practical purposes impossible to detect, but now scientists are coming up with some ideas for how graviton-detecting experiments could work for real. Let’s take a look. 🤓 Check out my new quiz app ➜ http://quizwithit.com/ 💌 Support me on Donorbox ➜ https://donorbox.org/swtg 📝 Transcripts and written news on Substack ➜ https://sciencewtg.substack.com/ 👉 Transcript with links to references on Patreon ➜ / sabine 📩 Free weekly science newsletter ➜ https://sabinehossenfelder.com/newsle… 👂 Audio only podcast ➜ https://open.spotify.com/show/0MkNfXl… 🔗 Join this channel to get access to perks ➜ / @sabinehossenfelder 🖼️ On instagram ➜ / sciencewtg #science #sciencenews #physics #gravity.
Gravitons are one of the most sought-after particles in physics. They could help physicists combine quantum physics with gravity to create a theory of \.
