US takes first step toward a quantum computing workforce

there already is one for Visual Studio!

https://www.microsoft.com/en-us/quantum/development-kit

It's actually a reasonable way to play around with simulations of quantum algorithms, much nicer than multiplying huge matrices which is typically what you'd otherwise do when learning. But it is a little silly that we have a quantum IDE before a usable quantum computer has been built.

The problem is that you will never know precisely where the plugin is installed.

We have demonstrated systems with a handful of quantum bits that worked as expected. There is a tremendous amount of work left before anything practical can be build, afaik.

We're really close. Actually Intel announced a 49-qubit quantum computer which would have beaten existing classical platforms, but just after that, another team at IBM [edit: not Intel] made an algorithmic breakthrough and simulated 56 qubits on a classical supercomputer. https://en.wikipedia.org/wiki/Quantum_supremacy

To your point, we invested billions in rockets before we knew we would go to the moon! Of course rockets were useful for moving bombs quickly in the meantime.

Quantum computers won't be faster at solving conventional problems, but they will be useful for simulating quantum behaviors related to chemistry and cosmology. Maybe we'll make sense of dark matter, who knows? I'm in the camp that we'll develop totally new problems to solve that didn't fit the domain of digital computers.

From a singular technology perspective, indeed it seems like investing a lot of money into a hypothetical device. However, there are many other factors you have to consider.

1. Quantum computing is a cryptographic arms race at the moment. One country can choose not the invest in it, but assuming QCs work, whichever country makes one first, is going to win big time. In a way, its a national security issue. Nobody wants to be left behind. Funding levels have to reflect this.

2. Many different architectures for QCs are being researched on, and in each area we have made tremendous advancements in new techniques of quantum-level-system control and new ways of nano scale manufacturing etc. The feedback alone from these advancements will enrich and enable many other areas of science and technology. For instance, the development of photonic quantum computation also advances the development of optical classical computer as the basic architecture is very similar.

3. Many physicists like myself don't care too much about actually building quantum computers, though it would be nice. Whether or not QCs are possible, just forcing ourselves to think about physical reality from a computational and information theoretic perspective has resulted in massive advancements in physics, a field which had pretty much stagnated since the 80s. The ideas generated from studying quantum information and computation have percolated into other areas of physics such as gravitation and the structure of spacetime. And its not sufficient to just think about QCs in the abstract. New ideas such as novel error correction codes are generated when physicists are forced to think about specific architectures and their limitations and/or real problems faced in the lab.

This is a very good point. Before seeing this point, my initial reaction was, "Nope, it's way too early to worry about quantum computing." But, the security cost / risk of being few years late can be so high for nations that they don't have a choice. They have to invest in it early.

I'd love to hear from crypto expert HNers about what the industry is doing to prepare for the possibility of quantum computing disrupting current crypto solutions and if there are any interesting (long-term) startup opportunities.

Cryptography is not that big of a deal imho. Post quantum cryptography is already a hot research area https://en.wikipedia.org/wiki/Post-quantum_cryptography so we'd probably figure something out to keep the very important secrets secret. More important is the tremendous advantage quantum computers will give is in materials science, chemistry, and biology. Suddenly we'll be able to efficiently simulate large molecules and their interactions. This will speed up research in those areas a lot because you need fewer difficult experiments. As I see it, scalable quantum computers are the key to Drexler type nanotechnology based on proteins.

A _cheap_ fast large quantum computer lets you break modern hybrid cryptography in real time. That is, you can choose to eavesdrop conversations or you can MITM them seamlessly. You also break forward secrecy (you can read conversations recorded today even though their participants can no longer read them by that point).

If, as seems rather more likely, your quantum computer is expensive you can't afford this. You have to pick what to see. If it isn't fast you can't MITM (imagine you're trying to connect to Hacker News and the browser mysteriously stalls for ten minutes, you're going to retry, and either it stalls again or this time they don't MITM you) and you have to pick what to see now versus later. And of course if it isn't large it's altogether useless against modern cryptography.

The chance a foreign adversary goes from zero to fast, cheap and large overnight is tiny. Its like going from the electric lightbulb straight to the integrated circuit before anybody else even had the electronic valve.

There's some caveats to mention here:

First, quantum computers don't scale as well as classical computers. You can take two 64-bit computers, connect them together and emulate a 128-bit computer, in classical computers. Or you could take one 64-bit computer and emulate 128-bits taking twice as long to compute it. But in classical computers, if you need 128 qubits for a computation, having even a 127-bit qubit computer leaves you dead in the water. In practical terms, Shor's algorithm requires O(n lg n) qubits, so you need thousands of qubits to try to break computer. You also can't parallelize Grover's algorithm by farming it out to N quantum computers.

Second, only a relatively small (but important) set of cryptography is actually affected by quantum computers. Symmetric ciphers generally only admit the quadratic speedup by Grover's algorithm, so breaking AES-128 requires 2^64 time on a quantum computer instead of 2^128 (and as mentioned above, having more computers doesn't help speed up the search). Where exponential speedup is available is mostly in public-key cryptography and key-exchange protocols. Forward secrecy (which is increasingly the norm in TLS connections) essentially means you have to crack each individual key exchange to read past conversations, not just the private keys.

Third, as others have mentioned, people are working on post-quantum cryptography. By the time that practical quantum computers for breaking RSA/ECC crypto come around, it's likely that the most useful things to break won't be breakable.

The citation for that line[0] says they are still testing it. From my reading it sounds like they built some hardware, but it doesn't work yet :-)

[0]: https://www.sciencenews.org/article/google-moves-toward-quan...

In the quote, "few hundred qubits", qubits are logical qubits. Google's 72-qubits are physical qubits. You implement error correction on the physical qubits, after which you are left with a lot fewer logical qubits, to do your actual computation with.

> Does the power of a quantum computer scale linearly with number of qubits?

It scales linearly with the number of logical qubits, in the same sense the power of a turing machine scales linearly with the size of the tape. Also, for a realistic system of hundreds of qubits, you will need tens of thousands of physical qubits.

> Does the difficulty in manufacturing scale linearly with number of qubits?

If you want the ability to do entangling operations on any two qubits, however far apart they are physically, the manufacturing difficulty scales quadratically with the number of qubits at least. However, you can choose to only have the ability to do entangling operations on near by qubits, and use swap operations to move the state of the qubits around. This will reduce manufacturing difficulty scaling, but will increase the time of any computation you perform.

On the contrary, there is a lot of engineering work to be done before we get a working quantum computer.

Mr. President, we must not allow... a mine shaft gap!

In my opinion, browse youtube for "microsoft q#" and check out their quantum development kit.

There will be the quantum mechanic quants that build new algorithms, but I think the Q# kit will be the SciKit of quantum and getting familiar with the classes and methods they provide will be a good step towards future-employability.

Seconded, how do you get started with quantum algorithms, architecture, etc...

Either learn the mathematics if you're interested in the software side, or learn the physics if you're interested in the hardware side.

You start as a quantum mechanic, and once you're confidently wielding your quantum wrench, you start attending classes at quantum night school.