Can you also explain quantum advantage for me?

I haven’t delved too much into the theory side of this, but so far “quantum advantage” has meant that researchers found a particular algorithm (doesn’t need to be practically useful) that their quantum processor can execute, but a “classical” computer cannot feasibly do (it would cost too much memory or too much time). Different research groups put different nuances on the term “quantum advantage” so it’s hard to give a straightforward answer.

And share your thoughts on what you think the timeline will look like for the development of quantum computing?

Difficult to say. There was a paper by Microsoft that showed what it would take to realize one of the first real practical applications (simulating chemical reactions for nitrogen fixation in fertilizers). On page 22 there is a table. When it comes to “clifford error rate”, the best qubits today can reach 10^-5 or so, and our control electronics are actually too noisy to get below ~10^-7 - 10^-8 if everything else were perfect. The best we can do on “required code distance” in practice up to now is 5.

TL;DR, 3 decades to get there would be a very optimistic estimate if we continue improving our current technology.

But, the “current technology” (the ones that all these papers by IBM, Google, etc. are about) is superconducting qubits. Many other platforms are being researched and show promise to be higher quality, but are simply not scalable yet. Microsoft is betting on the most stable, high-quality qubits we can think of (“Majorana qubits”), but they are so early in the research stage they haven’t even proven that you can actually make qubits that way.

Obviously there’s concerns that current cyphers will be obsolete, but I’ve always wondered is this not a problem that we could easily solve by just drastically ramping up entropy?

Quantum computers will be able to break asymmetric encryption that rely on prime factorization, like RSA, which happens to be by far the most widely used encryption algorithm today. Increasing the cipher length is not going to help you much since the quantum computer can scale much faster. Action should be taken now for critical environments (e.g. government, military) because of store now, decrypt later attacks.

Luckily there are encryption algorithms (like elliptic curve encryption, e.g. ECDSA) that have no known quantum algorithm to crack them. And if you’re paranoid that one day we will crack those algorithms too, quantum comes to the rescue with quantum encryption, which makes the encryption key generation fundamentally secure (as in, proven by physics that no third party could possibly listen in on the key generation). Quantum encryption is luckily much more easy to realize than quantum computing and it’s starting to become commercially available already (if you have a couple 10k dollars per link you want to secure).