FIU Quantum Distinguished Lecture: Excitonic Topological Quantum States and Route to Realize Charge Neutral Quantum Superfluidity

The excitonic insulator, an insulating phase formed by the spontaneous condensation of bound electron–hole pairs, has been sought for over half a century. Dr. Hossain will present the first unambiguous realization of a topological excitonic insulator in a three-dimensional topological quantum material. Using scanning tunneling microscopy, angle-resolved photoemission spectroscopy, and theoretical modeling, his team shows that Coulomb-driven exciton condensation opens a full bulk gap below ~100 K, and that this gap hosts gapless topological boundary modes. Below 5 K, a second, field-tunable excitonic instability emerges at finite momentum. These phases point to a bulk-crystal route to topologically protected quantum channels, coherent quantum transduction, and field-tunable quantum optoelectronic devices.