(Funded by the U.S. Department of Defense and the U.S. National Science Foundation)
Researchers from the City University of New York, Yale University, Caltech, Kansas State University, and international collaborators have discovered a new way of generating phonon-polaritons, a unique type of electromagnetic wave that occurs when light interacts with vibrations in a material’s crystal lattice structure. This advance could pave the way for cheaper, smaller long-wave infrared light sources and more efficient device cooling. The researchers made that discovery by using a thin layer of graphene sandwiched between two hexagonal boron nitride slabs. Until now, exciting and detecting phonon-polariton waves has been expensive – typically involving costly mid-infrared or terahertz lasers and near-field scanning probes – but in this study, the researchers used a cheaper alternative: an electrical current generated by applying an electric field to the graphene.

(Funded by the U.S. Department of Defense, the U.S. Department of Energy and the U.S. National Science Foundation)
Researchers at Caltech have developed an on-chip transducer that converts microwave photons to optical photons. The device involves a tiny silicon beam that vibrates at 5 gigahertz and couples to a microwave resonator – essentially a nanoscale box in which photons bounce around, also at 5 GHz. Using a technique called electrostatic actuation, a microwave photon is converted within that box to a mechanical vibration of the beam, and that mechanical oscillation, with the help of laser light, gets converted by the resonator into an optical photon. Such a conversion could enable the construction of large-scale distributed superconducting quantum computers.

(Funded by the U.S. Department of Energy and the National Institutes of Health)
Researchers at Cornell University have, for the first time, identified what happens when bacteria receive electrons from quantum dots. Using fluorescence lifetime imaging microscopy with two-photon excitation on a quantum dot and bacteria, the researchers identified a distinct halo surrounding the bacteria, which suggested the charge transfer was receiving some peripheral assistance. It turned out that an electron could either move directly from the quantum dot to the bacterium or be transferred from the bacterium via shuttle molecules. Photosynthetic biohybrids of this sort could potentially convert carbon dioxide into value-added chemical products, such as bioplastics and biofuels, and control other microbial processes.

(Funded by the U.S. Department of Defense)
By taking two flakes of special materials that are just one atom thick and twisting them at high angles, researchers at the University of Rochester have unlocked unique optical properties that could be used in quantum computers and other quantum technologies. Until now, scientists have explored the optical and electrical properties of 2D materials when layered on top of one another and twisted at very small angles (typically 1.1 degree). In this study, the researchers twisted layers of a 2D material, called molybdenum diselenide, at up to 40 degrees, and found that the resulting structure produced excitons – essentially, artificial atoms – that can act as quantum information bits, or qubits, and can retain information when activated by light. The research was conducted at the University of Rochester’s Integrated Nanosystems Center.

(Funded by the U.S. National Science Foundation)
Researchers from the University of Texas at Dallas, the Massachusetts Institute of Technology, and international collaborators have found that rhombohedral graphene behaves similarly to semiconductors and exhibits novel magnetism and superconductivity, as well as the quantum anomalous Hall effect, at extremely low temperatures. Graphene – a single layer of carbon atoms arranged in a flat honeycomb pattern – can be stacked in two different ways: Hexagonal stacking occurs when even-numbered graphene layers are aligned (with the odd-numbered layers rotated 60 degrees relative to the even layers); in contrast, rhombohedral stacking features a unidirectional 60-degree rotation for each successive layer.