" Google announced it has a quantum computer that is 100 million times faster than any classical computer in its lab. "
...except that even Google's classical computers are all hosted in datacenters with stupidly high specs and speeds, a magnitude faster than even enterprise servers I can rent from any old reseller or cloud provider. [I can rent 24-core servers at some places].
Hold that thought there.
Say you have a "classical computer" that's really just an aggregation of a bunch of dedicated systems similar to the ones powering their clouds. Now if you put enough of these together (as they probably did - into a cloud of course - remember that private clouds are also a thing), of course you will be able to make a classical computer that outperforms any other system.
Now considering that Google already has some of the most powerful classical computers, it's a no-brainer that they will also have one of the most powerful quantum computers as well.
Are they going to pass that on to end-users? Of course not. We're talking about internal hardware that powers things like Google Search and Youtube. They would never sell or even lease the hardware to third-parties, because they have no use for all that collective raw power.
Now a dumbed-down version of their QC that's much slower than your 100 million-x fast Google QC (we are talking around 100M x the speed of a
PC) -
that's more viable to be used in commercial settings (and hacker-oafs who attempt to use this to search the full 160-bits of BTC addresses, or the 256-bits of private keys).
Now 100M log 2 is about 26.5.
Assume the best single-PC build can crack 50 bits like a champ (and just for kicks, assume a cluster of 1000 of these can do 60 bits).
That means your rad, spiffy "x100M" commercial QC can only crack 76.5 bits feasibly (86.5 bits in a cluster of 1000). Nice, will solve you a few stubborn puzzles like #64+ and earn you a couple thousand dollars of
BTC, but nowhere near enough to threaten the security of secp256k1 or even HASH160.