Technical / Research

Researchers from Peking University and Beijing Normal University have reported orbital hybridization in graphene-based quantum dots, revealing how anisotropic confinement influences electronic states at the atomic scale. This represents a significant milestone in quantum physics and materials science, bridging the conceptual and experimental gap between artificial systems and the behaviors of real atoms.

Quantum dots, often described as artificial atoms, have been known to mimic certain characteristics of atomic orbitals. These nanostructures can recreate discrete energy levels and have successfully demonstrated artificial bonding and antibonding states. However, until now, they had not been used to simulate orbital hybridization—a fundamental process in real atoms where orbitals of different shapes and symmetries mix to form new, hybrid orbitals. This omission has limited the ability of artificial atoms to fully emulate the complexities of atomic structure. Moreover, a basic understanding of how anisotropic confinement—the directional variation in the spatial boundaries of a quantum dot—affects the potential for hybridization had been lacking.

Researchers from Yale University, California Institute of Technology, City University of New York, Kansas State University and ETH Zurich have reported a new way of generating long-wave infrared and terahertz waves. The work could pave the way towards cheaper, smaller long-wave infrared light sources and more efficient device cooling.

Phonon-polaritons are a unique type of electromagnetic wave that occurs when light interacts with vibrations in a material's crystal lattice structure. These phonon-polariton waves exhibit several unique characteristics. For example, they can concentrate the energy of long-wavelength infrared light into extremely small volumes, even down to tens of nanometers, as well as effectively move heat away from the source. This makes phonon-polaritons ideal for high-tech applications like sub-wavelength imaging, molecular sensors, and heat management within electronics. However, research on phonon-polariton waves has thus far mainly focused on fundamental studies in laboratory settings, with practical device applications remaining largely unexplored.

Researchers from Lithuania's Center for Physical Sciences and Technology and Kaunas University of Technology have reported a novel hybrid magnetic sensor that combines the unique properties of manganite and graphene to measure both the magnitude and direction of a magnetic field. 

The schematic drawing of the hybrid sensor. Image from: Scientific Reports

The sensor consists of a nanostructured manganite film to detect the magnetic field strength and a graphene layer to determine the angle between the magnetic field and the sensor plane. This dual sensor approach increases sensitivity over a wide range of magnetic field strengths and provides directional information, making it ideal for applications such as object positioning and navigation. 

Researchers from the University of Cambridge, CNRS and Imperial College London have used machine learning-driven molecular dynamics simulations to explore how defects in the surface of two-dimensional sheets alter ripple effects. 

They found that above a critical concentration of defects, free-standing graphene sheets undergo a dynamic transition from freely propagating to static ripples. The team's computational approach captures the dynamics with atomic resolution, and reveals that the transition is driven by elastic interactions between defects. The strength of these interactions is found to vary across defect types and a unifying set of principles was identified, driving the dynamic-to-static transition in 2D materials.

Researchers from Graz University of Technology, University of Florence,  Istituto Italiano di Tecnologia and Scuola Superiore Sant'Anna have demonstrated an innovative process that enables certain common dyes - found in standard marker pens - to be converted into laser-induced graphene (LIG).

The study focused on Eosin Y, a widely used xanthene dye, which exhibited excellent stability and structural properties ideal for laser conversion. While most existing LIG production relies on polymer precursors such as polyimide, this research shows that non-polymeric materials like dyes and inks can also serve as effective precursors. 

Researchers from MIT, Princeton University, SLAC National Accelerator Laboratory and Japan's National Institute for Materials Science have created a new ultrathin 2D material with unusual magnetic properties that initially surprised the researchers before they went on to solve the complicated puzzle behind those properties’ emergence. As a result, the work introduces a new platform for studying how materials behave at the most fundamental level — the world of quantum physics.

The scientists, led by MIT's Pablo Jarillo-Herrero, worked with three layers of graphene. Each layer was twisted on top of the next at the same angle, creating a helical structure reminiscent of a DNA helix.

Researchers from the University of British Columbia, the University of Washington, Johns Hopkins University and Japan's National Institute for Materials Science have identified a new class of quantum states in a custom-engineered graphene structure. Their new study reports the discovery of topological electronic crystals in twisted bilayer–trilayer graphene, a system created by introducing a precise rotational twist between stacked two-dimensional materials.

“The starting point for this work is two flakes of graphene, which are made up of carbon atoms arranged in a honeycomb structure. The way electrons hop between the carbon atoms determines the electrical properties of the graphene, which ends up being superficially similar to more common conductors like copper,” said Prof. Joshua Folk, a member of UBC’s Physics and Astronomy Department and the Blusson Quantum Matter Institute (UBC Blusson QMI).

Researchers from Penn State recently developed a portable and wireless device to simultaneously detect SARS-CoV-2, the virus that causes COVID-19, and vitamin C, a critical nutrient that helps bolster infection resistance, by integrating commercial transistors with printed laser-induced graphene.  

By simultaneously detecting the virus and vitamin C levels, the test could help individuals and their health care providers decide on more effective treatment options, the researchers said. For example, someone with low vitamin C levels may benefit from a supplemental boost, while someone with normal or high vitamin C levels may need to consider other options.  

Researchers from Canada's University of Ottawa, Iridian Spectral Technologies and University of Bayreuth in Germany have developed combined methods to enhance THz nonlinearities in graphene-based structures. The team's innovative methods aim to enhance frequency conversion of terahertz (THz) waves in graphene-based structures, unlocking new potential for faster, more efficient technologies in wireless communication and signal processing.

Schematic of the experimental configuration at the sample position to generate and detect THz third harmonic generation. Image from:  Light: Science & Applications 

THz waves, located in the far-infrared region of the electromagnetic spectrum, can be used to perform non-invasive imaging through opaque materials for security and quality control applications. Additionally, these waves hold promise for wireless communication. Advances in THz nonlinear optics, which can be used to change the frequency of electromagnetic waves, are essential for the development of high-speed wireless communication and signal processing systems for 6G technologies and beyond.

Researchers from Korea's Daegu Gyeongbuk Institute of Science and Technology (DGIST), Pohang University of Science and Technology, Institute for Basic Science, KAIST, Japan's National Institute for Materials Science and Max Planck Institute for Solid State Research in Germany have observed a unique quantum state in twisted bi-layer graphene.

This research provides insights into a quantum state that challenges the limitations of conventional semiconductor technology, broadening the horizon for quantum advancements and offering new avenues for technological innovation.