ADVANCED MATERIALS & PROCESSES | JULY 2026 5 RESEARCH TRACKS ULTRAFAST MICROSCOPY FOR OPTICAL PROCESSES Researchers at Heidelberg University, the Polytechnic University of Milan, and the Institute for Photonics and Nanotechnologies in Milan, developed an extremely fast microscopy method to research the interaction of light and matter—enabling the study of optical processes on very short timescales. At the center of the research is a pumpprobe microscope, which is used to conduct excitation and detection experiments. In this process, the material under investigation is first excited by a short light pulse, while a second pulse records the time-dependent response. By comparing measurements taken with the excitation on and off, these processes can be accurately reconstructed. “Combining holographic imaging with ultrafast spectroscopy allows us to spatially resolve electronic and magnetic dynamics and track them on timescales ranging from femtoseconds to picoseconds,” says researcher Julia Anthea Gessner of Heidelberg. The new method makes it possible to simultaneously image ultrafast electromagnetic phenomena across large fields of view. Unlike other microscopy techniques, this enables the imaging of areas on the micrometer scale and generating time-resolved films of the charge and spin dynamics of electrons. In addition, light- induced changes in the optical properties of materials can be made visible in this way. This high-resolution ultrafast imaging technique is primarily intended for energy materials used in solar cells, LEDs, spin-LEDs, and next-generation electronic components. www.uni-heidelberg.de. NEW NANOPARTICLE SUPERLATTICE Researchers from Brown University and the University of Michigan (U-M) used finely tuned nanoscale building blocks to stabilize a fleeting structural phase of matter that had been predicted theoretically but never stabilized in a physical material. The new nanoparticle superlattice (SL) freezes an elusive intermediate state between two of the most common crystal metallic arrangements, face-centered cubic (fcc) and body-centered cubic (bcc). Beyond describing new details about how this transition works, the novel structure exhibits extraordinary optical properties that could be useful in quantum computing or other quantum information systems. The research also provides a new recipe for using custom-shaped nanoparticles to engineer entirely new classes of materials with tailored properties. “Materials scientists have cared about how to control the amount of fcc and bcc in their metals for a long time, but the transitions between these phases have been hard to study because they are so unstable,” says researcher Tim Moore of U-M. “Being able to observe these structures is a fundamental breakthrough in materials science, and it gives us greater control over nanomaterial engineering.” Through light illumination, these silver nano- particle SLs exhibit hallmarks of deepstrong light-matter coupling, when electrons in the silver particles vibrate with light waves in perfect unison and become quantum mechanically entangled. These types of quantum optical interactions are often observed at very low temperatures, but this new structure appears to exhibit the behavior at room temperature. The researchers say this could provide a blueprint for making new materials for use in quantum computing or sensing. brown.edu. Optical setup for performing ultrafast holographic microscopy. Courtesy of Heidelberg University/Tobias Schwerdt. Fcc superlattices from spherical Ag-NCs from simulation of various patterns. Courtesy of Science, 2026, doi.org/ 10.1126/science.ady6472. (a) (b) (c) (d)
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