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Two-color light steers electrons through graphene’s transient topological state

The electronic properties of materials are typically determined by their structure under normal, undisturbed conditions, when they are in a state known as equilibrium. Intense light beams, however, can temporarily reshape a material’s electronic band structure (i.e., the range of energy states available to electrons), potentially giving rise to new electronic behaviors.

Researchers at Friedrich-Alexander University Erlangen-Nürnberg, Ludwig Maximilian University of Munich, the Technion—Israel Institute of Technology, and the University of Central Florida recently demonstrated that illuminating graphene with a specific type of light temporarily modifies its electron states, prompting the emergence of a so-called Floquet topological insulator.

This is a transient, out-of-equilibrium state created when a periodically oscillating field reshapes a material’s electronic structure, resulting in topological properties that are absent at equilibrium.

Quantum communication protocol enables three users to establish a shared secure key

Quantum key distribution allows two users to establish secret keys whose security is grounded in the laws of quantum mechanics. Extending this capability to multiple users is an essential step toward quantum networks that support secure communication among many participants. Quantum cryptographic conferencing addresses this need by enabling multiple users to share the same secure key, which they can then use to protect group communications.

In an article published in Physical Review Letters, a team led by professor Xiao-Song Ma at Nanjing University reports the experimental realization of asynchronous measurement-device-independent quantum cryptographic conferencing, or AMDI QCC. The demonstration addresses two major challenges in developing practical quantum networks: maintaining useful key-generation rates as networks grow and reducing the complexity of controlling optical phases.

As illustrated above, three users independently send optical pulses to a shared GHZ measurement station, where a fiber-based multipath interferometer enables interference between signals from different users and single-photon detection.

X-ray light is like guitar music, with frequencies sliding continuously between harmonics

Ultrashort laser pulses can be used to generate X-rays. Normally, however, only certain specific frequencies are produced. A team from TU Wien and the University of California San Diego has developed a method that makes it possible to tune the frequency continuously.

Using a six-meter-long gas-filled waveguide (20 feet long) containing the appropriate gas, the researchers can “detune” the light frequencies so that, in the end, exactly the required X-ray frequency is produced. The results have been published in the journal Communications Physics.

Photonic Legos of functional 3D thin-films unlock high-performance heterogeneous photonic integration

Photonic integrated circuits route information with optical signals instead of relying only on electrical currents. Silicon (Si) and silicon nitride (SiNx) are excellent photonic platforms for waveguides, but they cannot efficiently perform the ever-increasing tasks required for fully integrated optical systems. A heterogeneous photonic integration platform capable of interfacing different optical materials with high performance is thus an ongoing challenge for both academia and industry.

Conventional approaches use heteroepitaxy to realize thin-film functional materials on target optical substrates. However, this method confronts fundamental challenges in lattice matching and process compatibility, and substantially deteriorated epilayer material quality is often observed in mismatched photonic chips.

In our recent work published in Nature, a group of researchers from Washington University in St. Louis (WUSTL), the Swiss Federal Institute of Technology Lausanne (EPFL), and the Massachusetts Institute of Technology (MIT) demonstrated a different strategy: preparing desired thin-film materials on their most suitable parent substrates, then delaminating them into freestanding single-crystalline nanomembranes for unbridled heterogeneous photonic integration on arbitrary photonic templates.

Cooling liquids reveal self-limiting particle clusters behind glass transition

Before diving into the mystery of glass, theoretical physicist Corentin Laudicina takes us back to high school physics for a moment. Although he has spent years studying exactly what happens in a material during the glass transition, he also understands that his research is not the easiest thing to explain off the cuff at the cafeteria table.

According to school textbooks, matter can exist in three different states: gas, liquid and solid. Think of water vapor, liquid water and ice. The molecules that make up the material are the same, but the way they can move differs greatly, Laudicina explains.

He pulls out his dissertation and shows a figure from the introductory chapter. “The higher the temperature, the more freely the molecules can move. In a solid, they are arranged in a crystal lattice—in a fixed position, at a fixed distance from one another—but in a liquid, they can move without having a fixed position relative to each other. In the gas phase, those movements are even freer.”

Circular mRNA helps cell factories make up to six times as much protein

A synthetic biology technology has been developed that converts easily degraded messenger RNA (mRNA) into a ring-shaped form inside microbial cells, increasing protein production.

A research team led by Professor Sang Woo Seo of the Department of Chemical and Biological Engineering at Seoul National University College of Engineering has developed a synthetic biology technology that converts linear mRNA into a circular form inside microbial cells, simultaneously increasing mRNA stability and protein production efficiency. The team named the technology CRESEnT (Circular RNA Expression for Stable and Enhanced Translation).

Compared with a control in which circularization did not occur, CRESEnT increased fluorescent protein production by up to 5.95-fold and intracellular mRNA levels by 3.95-fold. The amount of protein produced per mRNA molecule also increased by 1.51-fold. The researchers confirmed the technology’s effectiveness not only in Escherichia coli but also in Bacillus subtilis and Corynebacterium glutamicum, and applied it to the production of valuable compounds including flaviolin, itaconic acid, lycopene and violacein.

Scientists teleport quantum states across 100 parallel optical channels

Quantum communication networks consist of several connected nodes that exchange information encoded in quantum states. These networks could potentially enable more secure communications between quantum devices in different locations.

One proposed approach for enabling quantum communication is known as quantum teleportation. This is a technique for transferring a quantum state carrying information between two systems by leveraging quantum entanglement, a phenomenon that links two or more quantum systems so that their properties remain correlated even when they are separated.

Researchers at East China Normal University recently demonstrated the teleportation of quantum information across 100 spatially distinct optical channels simultaneously in an experimental setting. Their paper, published in Physical Review Letters, introduces a new architecture for realizing quantum teleportation that could potentially be scaled up to larger networks.

Plasma technology could help plant-based packaging replace plastic

A new study has found a sustainable and scalable way to improve the durability of plant-based packaging; it’s a discovery that researchers say could help curb the environmental footprint of plastic. Researchers used advanced plasma technology to apply layered, protective coatings to the surface of cellulosic nanofibril (CNF) films, with the goal of reducing water absorption and improving moisture resistance.

They found that one of the plasma-treated coatings reduced liquid water absorption in CNF films to less than 1%, while another weakened the film’s moisture barrier and allowed more water vapor to pass through.

According to the researchers, the results show that the plasma technology—dielectric barrier discharge (DBD) plasma—can be used to precisely control how CNF films interact with moisture, opening new possibilities for plant-based packaging. The work is published in the journal Applied Surface Science.

Scientists reveal how our cells conduct emergency repairs for DNA

Two new studies from Johns Hopkins University are providing scientists with an unprecedented view of how human cells repair one of the most dangerous forms of genetic damage: a break that severs both strands of the DNA double helix.

Published back-to-back in Nature Communications, the studies examine different stages of a repair process called “non-homologous end joining,” or NHEJ. Together, the findings show how cells gain access to damaged DNA packaged inside chromatin and assemble a versatile collection of molecular tools to prepare and reconnect its broken ends.

The research could ultimately contribute to better cancer treatments and more predictable gene-editing techniques. Its immediate importance, however, lies in improving scientists’ fundamental understanding of a repair system that protects the human genome every day.

Jupiter uses a surprisingly complex system to fend off particles from the sun

A University of Iowa-led research team has reported in a new study the most detailed observations to date of the bow shock at Jupiter, our solar system’s gas giant. The findings from NASA’s Juno mission reveal key differences between Jupiter’s bow shock and Earth’s. They also may lead to a better understanding of the physics of how shocks function in even more powerful energy releases, such as those from dying stars. The research is published in Nature Communications.

The bow shock is an invisible boundary between the sun and a planet’s magnetic field. It is the first line of defense against the supersonic burst of energetic particles from the sun known as the solar wind.

On Earth, the bow shock is important because it marks the point where the solar wind is slowed, heated and then deflected around Earth. If that didn’t happen, our planet would be bombarded by the solar wind, and those harmful particles could reach our atmosphere and make Earth less safe for life.

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