Quantum Computer that is large enough would be bad for bitcoin, as it could get private key from your public key. But If you use bitcoin as recommended and you do not re-use your addresses, your public key is not visible, and even a big QC cant get your private key.

So if you use bitcoin as you should, your coins would still be safe.

Creating a bigger QC gets exponentially harder as the size increases. That is why building a QC big enough will take a lot of time, if it can ever even be made.
Googles QC was build for single purpose only and it is tiny  compared to what would be needed for cracking bitcoin. And also the calculation it made was quite different. It "proved" that something can't be done. Did it really prove that or were they a little optimistic at google? It is much easier to prove calculation to be correct, when you get a concrete result form it  

Also. QC would be really really bad at mining because SHA256 algorithm is considered quantum safe. Probably your laptop would be faster at mining than a QC

The real threat a large QC poses to bitcoin is the addresses that have their public keys visible. ALL of the big exchanges  keep their coins in addresses that are re-used, with visible public keys. And those addresses have loads of bitcoins. The 4 biggest ones have more than 100000BTC in each of them. That is more than 400000BTC. And lets not forget the 1M coins in Satoshi's addresses.
If someone steals all of them, that would make havoc to the value of bitcoin