Shor's algorithm shows how a quantum computer (with sufficiently many qubits) can solve the factorization problem efficiently. Also the discrete logarithm problem can be solved efficiently with such a quantum computer.
Both boil down into finding the period of a certain function.
Can quantum computer find the period of any given function efficiently? Are there any requirements towards the function?
Closely related, the discussed post-quantum schemes (e.g. the ones submitted to NIST) do not provide a function whose period could be exploited to break the scheme?