Feynman already articulated the one practical application for quantum computing: using it to simulate complex systems (https://www.optica-opn.org/home/articles/

Feynman already articulated the one practical application for quantum computing: using it to simulate complex systems (https://www.optica-opn.org/home/articles/on/volume_11/issue_2/features/quantum_mechanical_computers/ https://www.optica-opn.org/home/articles/on/volume_11/issue_... and https://calteches.library.caltech.edu/1976/ https://calteches.library.caltech.edu/1976/ and https://s2.smu.edu/~mitch/class/5395/papers/feynman-quantum-1981.pdf https://s2.smu.edu/~mitch/class/5395/papers/feynman-quantum-... These approaches are now being explored but I haven't seen any smoking guns showing a QC-based simulation exceeding the accuracy of a classical computer for a reasonable investment. Folks have suggested other areas, such as logistics, where finding small improvements to the best approximations might give a company a small edge, and crypto-breaking, but there has been not that much progress in this area, and the approximate methods have been improving rapidly.