News from the NNI Community - Research Advances Funded by Agencies Participating in the NNI

Researchers from the University of Maryland, the University of Maryland, the University of California, Los Angeles, and the National Institute of Standards and Technology have envisioned a modular system for scaling quantum processors with a flexible way of linking qubits over long distances. While there are many types of qubits, the researchers chose to study quantum dot-based spin qubits that interact through microwave photons in a superconducting cavity. (Quantum dots are semiconductor nanoparticles that have unique size- and shape-dependent optoelectronic properties.) The researchers provided comprehensive guidelines for tailored long-distance entangling links by making multiple frequencies available for each qubit to become linked with microwave cavity photons of a given frequency.

Physicists from Purdue University, Washington University in St. Louis, and the U.S. Department of Energy’s Sandia National Laboratories have levitated a fluorescent nanodiamond and spun it at incredibly high speeds (up to 1.2 billion times per minute). The fluorescent diamond emitted and scattered multicolor lights in different directions as it rotated. When illuminated by a green laser, the nanodiamond emitted red light, which was used to read out its electron spin states. An additional infrared laser was shone at the levitated nanodiamond to monitor its rotation. Like a disco ball, as the nanodiamond rotated, the direction of the scattered infrared light changed, carrying the rotation information of the nanodiamond.

Scientists from Yale University and the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory (BNL) have developed a systematic approach to understanding how energy is lost from the materials that make up qubits. Energy loss inhibits the performance of these quantum computer building blocks, so determining its sources can help bring researchers closer to designing quantum computers. To conduct this work, the scientists used electron microscopes from the Center for Functional Nanomaterials, a DOE-funded user facility at BNL.

Scientists from the U.S. Department of Energy's (DOE) Argonne National Laboratory (ANL) and the University of Chicago have developed a new technique to determine how nanoparticles move and interact with one another in soft matter when subjected to an applied force or temperature change. At the start, three bands of nanoparticles formed: fast moving, slow moving, and static. After 15 seconds, the fast-moving band vanished. About 40 seconds later, the three bands returned. To conduct these studies, the scientists used experimental equipment at the Center for Nanoscale Materials, a DOE-funded user facility at ANL.

Scientists from the Massachusetts Institute of Technology, Arizona State University, the U.S. Department of Energy’s Brookhaven National Laboratory, Sorbonne University in Paris, France, and Utrecht University in the Netherlands have reported new insights into exotic particles that are key to a form of magnetism that originates from ultrathin materials only a few atomic layers thick. The scientists identified the microscopic origin of these particles, known as excitons, and showed how they can be controlled by chemically “tuning” the material, which is primarily composed of nickel. Also, the scientists found that the excitons propagate throughout the bulk material instead of being bound to the nickel atoms.

The U.S. Environmental Protection Agency (EPA) is seeking applications for research to develop and demonstrate nanosensor technology with the potential to detect, monitor, and degrade per- and polyfluoroalkyl substances (PFAS) in groundwater or surface water that may be used as drinking water sources. Using nanotechnology may help to build better environmental sensors by reducing cost, improving efficiency, and increasing selectivity. Nanotechnology may also be used to degrade PFAS in a way that does not create toxic byproducts.

Researchers from Florida State University, the University of California Santa Barbara, Tsinghua University in China, Leipzig University in Germany, and Stuttgart University in Germany have identified, for the first time, the existence of local collective excitations of #electrons, called #plasmons, in a #Kagome metal – a class of materials whose atomic structure follows a hexagonal pattern that looks like a traditional Japanese basket weave – and found that the wavelength of those plasmons depends upon the thickness of the metal. The researchers also found that changing the frequency of a #laser shining at the metal caused the plasmons to spread through the material rather than staying confined to the surface. “[O]ur research reveals how electron interactions can create these unique waves at the nanoscale," said Guangxin Ni, the scientist who led this study. "This breakthrough is key for advancing technologies in nano-optics and nano-photonics."

Putting 50 billion transistors into a microchip the size of a fingernail is a feat that requires manufacturing methods of nanometer-level precision. The process relies heavily on solvents that carry and deposit materials in each layer – solvents that can be difficult to handle and toxic to the environment. Now, researchers from Tufts University and Istituto Italiano di Tecnologia in Milan, Italy, have developed a nanomanufacturing approach that uses water as the primary solvent, making it more environmentally compatible and opening the door to the development of devices that combine inorganic and biological materials.

Researchers from the University of California San Diego have developed an innovative approach to multispectral photodetection by alternating layers of graphene and colloidal quantum dots. By carefully engineering the material stack, the researchers created photodetectors sensitive to different wavelength bands without additional optical components. The key innovation lies in using graphene monolayers as independent charge collectors at different depths within a quantum dot absorber layer.

Researchers from Penn State and the National Institute for Materials Science in Japan have created a switch that turns on and off the presence of “kink states” – electrical conduction pathways at the edge of semiconducting materials. By controlling the formation of the kink states, researchers can regulate the flow of electrons in a quantum system. Kink states exist in a quantum device built with a bilayer graphene, which comprises two layers of atomically thin carbon stacked together, in such a way that the atoms in one layer are misaligned to the atoms in the other. "The amazing thing about our devices is that we can make electrons moving in opposite directions not collide with one another … even though they share the same pathways," said Ke Huang, one of the scientists involved in this study.