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Researchers at Rice University have made a meaningful advance in the simulation of molecular electron transfer—a fundamental process underpinning countless physical, chemical and biological processes. The study, published in Science Advances, details the use of a trapped-ion quantum simulator to model electron transfer dynamics with unprecedented tunability, unlocking new opportunities for scientific exploration in fields ranging from molecular electronics to photosynthesis.

Electron transfer, critical to processes such as cellular respiration and energy harvesting in plants, has long posed challenges to scientists due to the complex quantum interactions involved. Current computational techniques often fall short of capturing the full scope of these processes. The multidisciplinary team at Rice, including physicists, chemists and biologists, addressed these challenges by creating a programmable quantum system capable of independently controlling the key factors in electron transfer: donor-acceptor energy gaps, electronic and vibronic couplings and environmental dissipation.

Using an ion crystal trapped in a vacuum system and manipulated by laser light, the researchers demonstrated the ability to simulate real-time spin dynamics and measure transfer rates across a range of conditions. The findings not only validate key theories of quantum mechanics but also pave the way for novel insights into light-harvesting systems and molecular devices.

Reliably measuring the polarization state of light is crucial for various technological applications, ranging from optical communication to biomedical imaging. Yet conventional polarimeters are made of bulky components, which makes them difficult to reduce in size and limits their widespread adoption.

Researchers at the Shanghai Institute of Technical Physics (SITP) of the Chinese Academy of Sciences and other institutes recently developed an on-chip full-Stokes polarimeter that could be easier to deploy on a large scale. Their device, presented in a paper in Nature Electronics, is based on optoelectronic polarization eigenvectors, mathematical equations that represent the linear relationship between the incident Stokes vector and a detector’s photocurrent.

“This work was driven by the growing demand for compact, high-performance polarization analysis devices in optoelectronics,” Jing Zhou, corresponding author of the paper, told Phys.org. “Traditional polarimeters, which rely on discrete bulky optical components, present significant challenges to miniaturization and limit their broader applicability. Our main goal is to develop an on-chip solution capable of direct electrical readout to reconstruct full-Stokes polarization states.”

Colloidal gels are complex systems made up of microscopic particles dispersed in a liquid, ultimately producing a semi-solid network. These materials have unique and advantageous properties that can be tuned using external forces, which have been the focus of various physics studies.

Researchers at University of Copenhagen in Denmark and the UGC-DAE Consortium for Scientific Research in India recently ran simulations and performed analyses aimed at understanding how the injection of active particles, such as swimming bacteria, would influence colloidal gels.

Their paper, published in Physical Review Letters, shows that active particles can influence the structure of 3D colloidal gels, kneading them into porous and denser structures.

Northwestern University engineers are the first to successfully demonstrate quantum teleportation over a fiberoptic cable already carrying internet traffic.

The discovery introduces the new possibility of combining quantum communication with existing internet cables—greatly simplifying the infrastructure required for distributed quantum sensing or computing applications.

The study is published on the arXiv preprint server and is due to appear in the journal Optica.

Solid-state lithium batteries are promising energy storage solutions that utilize solid electrolytes as opposed to the liquid or gel electrolytes found in traditional lithium-ion batteries (LiBs). Compared to LiBs and other batteries that are used worldwide, these batteries could attain significantly higher energy densities of more than 500 Wh/kg⁻¹ and 1,000 Wh/l⁻¹, which could be advantageous for powering electric vehicles and other electronics for longer periods of time.

Despite their possible advantages, existing solid-state lithium batteries exhibit significant limitations that have so far prevented their large-scale deployment. These include the active lithium loss that can occur while the batteries are charged and discharged, which can reduce their efficiency and overall performance.

This loss of lithium is caused by an inhomogeneous lithium plating. Devising effective strategies and thin lithium metal foils that could limit the loss of lithium in solid-state batteries is thus a key goal for the energy research community.

Quantum walks are a powerful theoretical model using quantum effects such as superposition, interference and entanglement to achieve computing power beyond classical methods.

A research team at the National Innovation Institute of Defense Technology from the Academy of Military Sciences (China) recently published a review article that thoroughly summarizes the theories and characteristics, physical implementations, applications and challenges of quantum walks and quantum walk computing. The review was published Nov. 13 in Intelligent Computing in an article titled “Quantum Walk Computing: Theory, Implementation, and Application.”

As quantum mechanical equivalents of classical random walks, quantum walks use quantum phenomena to design advanced algorithms for applications such as database search, network analysis and navigation, and quantum simulations. Different types of quantum walks include discrete-time quantum walks, continuous-time quantum walks, discontinuous quantum walks, and nonunitary quantum walks. Each model presents unique features and computational advantages.

A method for imaging spin waves in magnetic materials uses flash-like intensity variations in a laser beam to capture the wave motion at specific moments in time.

The magnetic moments, or spins, in certain materials can twirl in a coordinated wave pattern that might one day be used to transmit information in so-called spintronic devices. Researchers have developed a new way to image these spin waves using an infrared laser that essentially flashes on and off at a frequency that matches that of the spin waves [1]. Unlike other spin-wave probes, this strobe method can directly capture phase information that is relevant to certain applications, such as hybrid devices that combine spin waves with other types of waves.

A spin wave can be triggered in a magnetic material when some perturbation causes a spin to oscillate, which can then generate a wave of oscillations that ripple through neighboring spins. Spin waves have several properties that make them good candidates for information carriers. For one, they have relatively small wavelengths—a few hundred nanometers at a frequency of 1 GHz, whereas a 1-GHz photon has a wavelength of about 30 cm. This compactness could conceivably allow researchers to build spintronic components, such as waveguides and logic gates, at the nanoscale. Another advantage of these waves is that the spins remain in place, and only their orientation changes. So the heat losses that affect the moving charges in traditional electronics don’t exist.

The search for superconductivity in hydrogen-rich compounds known as hydrides has been an emotional rollercoaster ride for the scientific community. Excitement mounted a few years ago, as hydride experiments had physicists imagining that a Holy Grail, room-temperature superconductivity, might be within reach. But the field was shocked in 2023 by allegations of malpractice and fraud. Now a group of physicists—leading superconductivity experts who aren’t involved in hydride research—has offered an independent assessment of the available body of work on these materials [1]. They conclude that there is overwhelming evidence for superconductivity in hydrides.

“The more I read the foundational literature, and the more I learned about the way that results were being repeated, the more it became clear to me that hydride superconductivity is completely genuine,” says Andrew Mackenzie of the Max Planck Institute for Chemical Physics of Solids in Germany and the University of St Andrews in the UK.

Mackenzie was one of the initiators of the group’s work. “At conferences last spring, guys my age were having lots of young people coming up to ask: What’s going on in hydrides?” he says. After a communal discussion at a superconductivity meeting in Berlin in August, he and other researchers thought that something needed to be done to address young researchers’ concerns. They organized a group that would review available data with the goal of delivering an objective evaluation of hydride superconductivity claims, says Jörg Schmalian of the Karlsruhe Institute of Technology in Germany, who is one of the article’s cosigners.

In 2011 physicists made a surprising observation: A cuprate material exposed to intense pulses of light appeared to superconduct fleetingly at a temperature above its critical temperature. Could this be a clue to finding higher-temperature superconductors? The answer remains unclear. “There are still continuing debates about whether the light-induced state is really superconducting,” says Morihiko Nishida from the University of Tokyo. Now he and his colleagues have provided new hints concerning the nature of the light-induced state and its connection to electronic wave patterns called charge-density waves (CDWs) [1].

The researchers studied two cuprates, called LNSCO and LSCO, that both contain the element lanthanum. These materials superconduct at temperatures below 10 K, but at slightly higher temperatures, they transition to one of several low-conductivity states in which a wave pattern is imprinted onto the electron distribution. Previous work by this group suggested that these CDWs play a role in light-induced superconductivity [2], but it was unclear whether the wavelength—short or long—of the CDWs had any effect.

In their new experiments, Nishida and colleagues fired near-infrared pulses at their cuprate samples and recorded the electron response with a terahertz probe beam. In the CDW region of parameter space, they observed a light-induced conducting state whose frequency matched that of a superconducting resonance effect. The implication that the light-induced state is superconducting needs to be confirmed with other experiments, but the team’s work has revealed that both short-and long-wavelength CDWs play a role. The results have a bearing on models that suggest that the pairing of electrons—a key feature of superconductivity—occurs in CDW states at temperatures above the normal onset of superconductivity (see Synopsis: Picking out Waves in a Material’s Charge Distribution).