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

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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.