Hi I've been hearing for years now that quantum computers have the potential to render encryption obsolete. My layman's understanding is that it would do this by taking advantage of the fact that qbits can exist in multiple states not just zero and one. I imagine there must be some limit to how efficient even quantum computers can be, so was wondering if encryption could be rendered safe with sufficiently large keys? If a quantum computer can make quick work of 512 bit encryption, how about 1 million bit encryption? 1 billion bit encryption? Is there some point where it would take absurdly long times to crack an encrypted message even with a quantum computer?