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Dark states are quantum states in which a system does not interact with external fields, such as light (i.e., photons) or electromagnetic fields. These states, which generally occur due to interferences between the pathways through which a system interacts with an external field, are undetectable using spectroscopic techniques.

Integrated photonic circuits operating at room temperature combined with optical nonlinear effects could revolutionize both classical and quantum signal processing. Scientists from the Faculty of Physics at the University of Warsaw, in collaboration with other institutions from Poland as well as Italy, Iceland, and Australia, have demonstrated the creation of perovskite crystals with predefined shapes that can serve in nonlinear photonics as waveguides, couplers, splitters, and modulators.

Just a few years ago, researchers discovered that changing the angle between two layers of graphene, an atom-thick sheet of carbon, also changed the material’s electronic and optical properties. They then learned that a “twist” of 1.1 degrees—dubbed the “magic” angle—could transform this metallic material into an insulator or a superconductor, a finding that ignited excitement about a possible pathway to new quantum technologies.

Lithium iron phosphate is one of the most important materials for batteries in electric cars, stationary energy storage systems and tools. It has a long service life, is comparatively inexpensive and does not tend to spontaneously combust. Energy density is also making progress. However, experts are still puzzled as to why lithium iron phosphate batteries undercut their theoretical electricity storage capacity by up to 25% in practice.

In order to utilize this dormant capacity reserve, it would be crucial to know exactly where and how lithium ions are stored in and released from the during the charging and discharging cycles.

Researchers at Graz University of Technology (TU Graz) have now taken a significant step in this direction. Using transmission electron microscopes, they were able to systematically track the lithium ions as they traveled through the battery material, map their arrangement in the crystal lattice of an iron phosphate cathode with unprecedented resolution and precisely quantify their distribution in the crystal.