(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. 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.

(Funded by the National Institutes of Health and the U.S. National Science Foundation)
Researchers from Carnegie Mellon University and the University of Southern California have devised a method to create large amounts of a material that can be used to make two-dimensional (2D) semiconductors with record high performance. That material, tellurium, has a fast conducting speed and is stable in the air, so it does not easily degrade. The researchers used 2D tellurium to create an ultralight-weight photodetector – a device that can detect light – which is highly tunable, allowing its parameters to be changed so it can be used in a variety of applications, a property that is not true of other photodetectors.

(Funded by the National Institutes of Health and the U.S. National Science Foundation)
Researchers from the University of Rhode Island and Brown University have shown that carbon nanotubes could be combined with machine learning to detect subtle differences between closely related immune cells. The researchers used an in vitro experiment that involved placing live cells into a culture dish, adding carbon nanotubes, and then using a specialized microscope with an infrared camera to observe the emitted light from each cell. The camera generated millions of data points, each of which reflected cellular activity. Healthy cells emitted one type of light, while potentially unhealthy or changing cells emitted different light patterns.