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A new study in Physical Review Letters illuminates the intricacies of energy exchanges within bipartite quantum systems, offering profound insights into quantum coherence, pure dephasing effects, and the potential impact on future quantum technologies.

In quantum systems, the behavior of particles and energy transfer are governed by probability distributions and wave functions, adding layers of complexity to the understanding of energy exchanges.

The exploration of energy exchanges in quantum systems inherently involves tackling the complexities arising from quantum decoherence and the scales at which quantum systems operate, introducing sensitivity.

For the first time, researchers have demonstrated the remarkable ability to perturb pairs of spatially separated yet interconnected quantum entangled particles without altering their shared properties.

The team includes researchers from the Structured Light Laboratory (School of Physics) at the University of the Witwatersrand in South Africa, led by Professor Andrew Forbes, in collaboration with string theorist Robert de Mello Koch from Huzhou University in China (previously from Wits University).

“We achieved this experimental milestone by entangling two identical photons and customizing their shared wave-function in such a way that their topology or structure becomes apparent only when the photons are treated as a unified entity,” explains lead author, Pedro Ornelas, an MSc student in the structured light laboratory.

Darwin applied the theory of evolution to life on earth, but not to other massively complex systems like planets, stars, atoms and minerals. Now, an interdisciplinary group of researchers has identified a missing aspect of that theory that applies to essentially everything.

Their paper, “On the roles of function and selection in evolving systems,” published Oct. 16 in the Proceedings of the National Academy of Sciences, describes “a missing law of nature” that recognizes for the first time an important norm within the natural world’s workings. The new law states that complex natural systems evolve to states of greater patterning, diversity and complexity.

“This was a true collaboration between scientists and philosophers to address one of the most profound mysteries of the cosmos: why do complex systems, including life, evolve toward greater functional information over time?” said co-author Jonathan Lunine, the David C. Duncan Professor in the Physical Sciences and chair of astronomy in the College of Arts and Sciences.

The work demonstrates control over key properties leading to better performance.

MIT researchers and colleagues have demonstrated a way to precisely control the size, composition, and other properties of nanoparticles key to the reactions involved in a variety of clean energy and environmental technologies. They did so by leveraging ion irradiation, a technique in which beams of charged particles bombard a material.

They went on to show that nanoparticles created this way have superior performance over their conventionally made counterparts.

Quantum computing is becoming more accessible for performing calculations. However, research indicates that there are inherent limitations, particularly related to the quality of the clock utilized.

There are different ideas about how quantum computers could be built. But they all have one thing in common: you use a quantum physical system – for example, individual atoms – and change their state by exposing them to very specific forces for a specific time. However, this means that in order to be able to rely on the quantum computing operation delivering the correct result, you need a clock that is as precise as possible.

But here you run into problems: perfect time measurement is impossible. Every clock has two fundamental properties: a certain precision and a certain time resolution. The time resolution indicates how small the time intervals are that can be measured – i.e. how quickly the clock ticks. Precision tells you how much inaccuracy you have to expect with every single tick.

First, we halved the deep methane abundance (model A), since we know the polar regions are methane-depleted, but found that although such a change produces changes in (I/F)₀ and k that reasonably approximate the shape of observed differences between the polar and equatorial regions in Fig. 12, the amplitude is not sufficiently large and is close to zero at blue wavelengths. Secondly, we tried halving the methane abundance and increasing the opacity of the Aerosol-2 layer, τ₂, by 1.0 (model B), from 4.6 to 5.6. Note that all opacities quoted here are at a reference wavelength of 800 nm. Here, we see an increase in the (I/F)₀ and k difference at green wavelengths, but a decrease at blue wavelengths. The reason for this is that the Aerosol-2 particles are retrieved to have increased imaginary refractive index at blue wavelengths (Irwin et al. 2022), which lowers the single-scattering albedo here. Hence, increasing the Aerosol-2 opacity reduces the reflectivity at blue wavelengths, rather than increasing it. How then can we match the observed differences between the polar and equatorial spectra of the 2002 HST/STIS data? In the study of James et al. (2023), noted earlier, it was found that the optimal solution was to not only increase the opacity of the particles in the Aerosol-2 layer, but also make them more reflective at wavelengths longer than 500 nm. We could have similarly adjusted the imaginary refractive index spectra, n_imag, of the Aerosol-2 particles (lower n_imag values increase the single-scattering albedo), but in a parallel analysis of VLT/MUSE observations of Neptune, Irwin et al. (2023b) found that the observed spectra of deep bright spots could be well approximated by adding a component of bright particles to the existing Aerosol-1 layer at ∼5 bar. We wondered whether a similar approach might be applicable here. Changes in the Aerosol-1 layer cannot account for the observed HST/STIS pole–equator differences, since this layer is only detectable in narrow wavelength bands of very low methane absorption, but in Fig. 12 it can be seen that if we add a unit opacity of conservatively scattering particles to the Aerosol-2 layer at 1–2 bar (with the same Gamma size distribution as the Aerosol-2 particles, with mean radius 0.6 μm and variance σ = 0.3) the (I/F)₀ and k difference increases at all wavelengths longer than ∼ 480 nm (model X), although not as much as the difference between polar and equatorial latitudes. However, if we add this additional opacity and simultaneously halve the methane abundance (Model C1) we find that the differences in the (I/F)₀ and k spectra agree moderately well with the observed pole–equator difference spectra at most wavelengths. What might be responsible for this extra component of bright particles in the Aerosol-2 layer will be discussed further, but it could indicate that more methane ice particles are present in the haze/methane-ice layer, or that more methane ice is condensed onto the haze Cloud Condensation Nuclei (CCN). Whatever the cause, it is clear that the spectral difference between the polar and equatorial regions seen by HST/STIS in 2002 is consistent with a reduction in methane abundance coupled with an increase in the reflectivity of the particles in the Aerosol-2 layer that could be caused by the addition of a conservatively scattering component.

Having surveyed the possible interpretations of the HST/STIS polar and equatorial spectra, we then tested these models against the seasonal photometric magnitude data. While the Lowell Observatory magnitude data accurately preserve the quantities that were measured, they are a less intuitive measure for interpreting the changes in Uranus’s reflectivity spectrum with atmospheric models. Hence, we converted the magnitudes to the mean disc-averaged reflectivities of Uranus, which also corrects out the solid-angle variations of Uranus’s disc size, noted earlier. This conversion was done using the procedures outlined in Appendix B. The resulting seasonal variations in disc-averaged reflectivity at the blue and green wavelengths of the Strömgren b and y filters are shown in Fig. 13. Here, it can be seen that the disc-averaged green reflectivity of Uranus changes from ∼0.47 to ∼0.

Physicists at the National University of Singapore have innovated a concept to induce and directly quantify spin splitting in two-dimensional materials. By using this concept, they have experimentally achieved large tunability and a high degree of spin-polarisation in graphene. This research achievement can potentially advance the field of two-dimensional (2D) spintronics, with applications for low-power electronics.

Joule heating poses a significant challenge in modern electronics, especially in devices such as personal computers and smartphones. This is an effect that occurs when the flow of electrical current passing through a material produces thermal energy, subsequently raising the material’s temperature.

One potential solution involves the use of spin, instead of charge, in logic circuits. These circuits can, in principle, offer low-power consumption and ultrafast speed, owing to the reduction or elimination of Joule heating. This has given rise to the emerging field of spintronics.

To that end, Caplan is part of a crew that posits the dark matter portion of the dark universe could very well be made up of not particles like we imagine, but instead a huge number of atom-size black holes produced during the dawn of the universe, each of which is about as massive as a typical asteroid in our own solar system. “I think all dark matter candidates are just a little bit wild,” Caplan, who is an assistant professor of physics at Illinois State University, told Space.com. “Some guesses are better than others, and primordial black holes are taken seriously. I’ll go so far as to say I think they’re popular.”

But to turn the hypothesis into fact, he says, scientists have to actually find one of these miniscule ancient voids — which brings us to this new black-hole-sun conversation. Potentially, Caplan and his co-authors say in their papers, some of those ultrasmall black holes might’ve gotten caught up in dust clouds in the midst of forming stars. Potentially, they might’ve ended up literally lodged in those eventual sparkling oceans of plasma. Potentially, they might still be there.

So, no, there is probably not a black hole in the center of our star — but there might be other stars gallivanting through space with black holes indeed wedged within their hearts.

Ever think you’d see a single atom without staring down the barrel of a powerful microscope? Oxford University physicist David Nadlinger has won the top prize in the fifth annual Engineering and Physical Sciences Research Council’s (EPSRC) national science photography competition for his image ‘Single Atom in an Ion Trap’, which does something incredible: makes a single atom visible to the human eye.

Click image to zoom. Photo: David Nadlinger/EPSRC

Captured on an ordinary digital camera, the image shows an atom of strontium suspended by electric fields emanating from the metal electrodes of an ion trap—those electrodes are about 2mm apart. Nadlinger shot the photo through the window of the ultra-high vacuum chamber that houses the ion trap, which is used to explore the potential of laser-cooled atomic ions in new applications such as highly accurate atomic clocks and sensors, and quantum computing.