Kavli Institute Nanoscience Highlights

Kavli Institute researchers have spent an active summer, publishing advances in everything from quantum and superconducting materials to bionanoscience, quantum optics, and the development of new devices capable of storing quantum information as vibrations for prolonged periods of time.

Materials

As researchers achieve ever more precise control over materials and nanostructures, their ability to manipulate quantum phenomena grows. This starts with a more detailed understanding of material behavior.

• At the Kavli Institute at Cornell, J.C. Séamus Davis and colleagues created an unusual topological superconductor, whose electron pairing had previously been seen only in highly condensed helium. Also unique, the electrons in his uranium ditelluride system form periodic crystalline patterns in space.
• Katja Nowack found a new way to measure the flow of electrons in a quantum anomalous Hall insulator. For 40 years, scientists believed current flowed only on the surface of these materials, but Nowack’s findings revaled current moving inside as well—turning current theory on its head.
• Debanjan Chowdhury has been comparing similar crystals to understand why superconductors lose their resistance-free conductivity as they get warmer. Researchers believe this is due to changes in magnetic moment within the material, but Chowdhury finds the interaction of electrons with the vibration of the crystal and localized magnetic spins also play a role.
• Meanwhile, Kobus Kuipers, co-director of the Kavli Institute of Nanoscience Delft, and colleagues received a 21.5 million grant to develop new materials for quantum and classical computing.

Bio-inspired nanoscience

While nanoscience tools have led to many advances in biology and medicine, they are also enabling new ways to think about information processing.

• A case in point is the work of Alireza Marandi at the Kavli Nanoscience Institute at Caltech, who explores using light instead of electrons for computing. Instead of trying to replicate the devices used in digital computing, he is drawing inspiration from ants and termites, who build large, ventilated nests using simple structural rules. His goal is to create self-assembling cells that can process information without the auxiliary devices typically required for moving and storing light-based information.
• At the Kavli Institute of Nanoscience Discovery at Oxford, George Tofaris is unraveling the mysteries of Parkinson’s disease. We already know that when the brain fails to eliminate a protein that helps neurons communicate, it builds up and kills adjacent neurons. Tofaris has developed a new tool that enabled his team to locate three sites that destroy this protein, giving investigators a new target for potential therapies.

Light

The quantum nature of light—its ability to act as both a particle and a wave—has attracted research attention for generations.

• At the Kavli Energy NanoScience Institute at UC Berkeley, Graham Fleming and Birgitta Whaley have answered an age-old question: just how much light does it take to initiate photosynthesis. The answer is just one photon, and the way the researchers proved this could open the door to studying how individual proteins transfer energy during each step of photosynthesis.
• Meanwhile, at the Kavli Nanoscience Institute at Caltech, Andrei Faraon is using algorithms to "evolve” metamaterials to do unusual things, like split light into its components. Fitted over a lens, these materials could enable cameras to detect the orientation of surfaces, a useful ability for the creation of augmented and virtual reality spaces.
• Also at Caltech, Kavli member Harry Atwater’s team has found a way to get around Kirchholff’s Law, which describes how an object left in the sun will reach an equilibrium point where the heat it emits balances the solar energy it absorbs. This may help the researchers make more efficient solar cells by reducing the potential electrical power lost as heat.

Devices

There are a seemingly unlimited number of ways nanoscale structures can influence quantum interactions.

• This summer, for example, Mohammad Mirhosseini of the Kavli Nanoscience Institute at Caltech demonstrated he could store quantum information as a phonon (a quantum unit of vibration, or sound) for two orders of magnitude longer than other mechanical devices. His secret: most phonon-based systems use piezoelectrics, which turn electricity into motion. Mirhosseini uses flexible nanoscale plates that vibrate at extremely high frequencies.
• At the Kavli Energy NanoScience Institute, co-director Omar Yaghi unveiled a machine learning system that enabled him to double the amount of water his ultraporous metal-organic framework materials could harvest from dry desert air. He also tripled system productivity (water harvested per square meter) with a material that lasts for years without replacement.