[aparent]

You are mostly correct. In fact the key strength of something like AES is realistically not even going to be reduced by half. In terms of the query complexity (the number of calls to AES that are needed) using Grover's algorithm the key strength is half what it would be with classical brute force. In practice though these queries must be implemented as quantum circuits and run a on quantum computer which adds a pretty large overhead.

This article is about the implementation of an asymmetric protocol based on the RLWE (https://en.wikipedia.org/wiki/Ring_Learning_with_Errors) problem.