I am the lead co-author behind ACM’s TechBrief on Quantum Computing and Simulation. Ask me anything!

What questions do you wish people would ask about you quantum computing (and what's your answer)?

Great question! Almost everyone asks about cryptanalysis. But we (Simson Garfinkel) and I think the real action is in quantum sensing and simulation and wish more questions were raised about those categories of quantum technologies (QTs). Sensing and simulation are both more difficult to understand, but plumbing them reveals all sorts of interesting implications. The more prosaic implications surround civil liberties: what will it mean when sensing only available to militaries, intelligence agencies, and sophisticated companies (like extraction industry) devolve to law enforcement uses? This could trigger a fundamental rethink of observation in "public."

The implications of simulation are far more exciting than codebreaking. There's a nice consensus statement about the field here: https://arxiv.org/abs/1912.06938 I suspect the general excitement and familiarity about computing causes us not to see wet-sciences innovations that could change our lives.

What are my legal liabilities if my quantum computer inadvertently summonses Cthulhu from the nightmare corpse-city of R'lyeh, sunk beneath the sea? I'm asking for a friend.

Just how inadvertent is this summons? Is this an intentional act, or an accident? How foreseeable is the link between your QC use and Cthulhu's rise?

I suspect that you will not be held responsible because you have several good defenses: a lack of foreseeability, you shouldn't be responsible for the intentional wrongs of a monster, and because this sounds like an act of god :)

Are you a fan of RTL? I wish I could have afforded to go to this: https://www.youtube.com/watch?v=MOvA1MtOKFg

My first question would be: Why is an attorney / law professor conducting an AMA on quantum simulation and not someone with a background in mathematics and/or physics? Do you have any other education or experience that is relevant to quantum computing?

Edit: oh this is just an AMA announcement. You should make that clear in the title of the post.

As a physicist working in quantum computing, I deeply hope he is only going to talk about legal implications of the technology. One of my biggest frustrations is the number of people that don't know quantum anything, talking about QC.

What do you think policymakers should know about QC?

It's a tricky question because in a sense, policymakers have to think ahead of science. But (in my biased political view) at least be aware of when/where a certain technology will be a threat to people/environment and/or increase the unbalance in power heavily. In case of quantum computing, probably know the most imminent user cases and how it might impact economic and socially people and organizations.

FWIW, President Biden's OSTP has excellent, serious experts. But much of the policy consideration is about staying ahead of China. The most frequent question I get is "what can we export control?"

At Berkeley, I am one of the bridges between pure social science like law and the computing world. I'm dually appointed in the law and information schools and teach python programming to lawyers. Technology is just a skill that people pick up, like everything else, tech literacy requires experimentation and some faking it.

Writing this book was a tremendous challenge because I do not have a STEM background and Simson Garfinkel's PhD is in computer science (MIT).

Interestingly, the initial reviewers hated the pure science portions of the book, said it was in essence a physics textbook, and so we moved that material to the appendixes. Almost everyone who read it wanted a functional explanation of the technology instead of a scientific one.

I do think one public service we performed was to surface high quality translation pieces. This one on quantum simulation is great: https://arxiv.org/abs/1912.06938 And on quantum computing, the Academies report from 2019 is objective and a nice alternative to the hype: https://nap.nationalacademies.org/catalog/25196/quantum-computing-progress-and-prospects

Is quantum computing being miniaturized, and might it someday have applications for home use? Or will this always be an industrial technology, and potentially only of marginal use aside from some very specialized cases?

We use the analogy of the GPU to explain quantum computing (QC)---QCs will be special purpose devices for special computations. Our regular computers will do most of what we need to do nicely :) From a TRL perspective, QC looks like an industrial technology.

Miniaturization depends on QC having a breakthrough similar to the development of the transistor. Right now, QC is in a pre-transistor phase where different competitors are using different substrates to achieve quantum effects. It's something like the relay/tube era.

Miniaturization is one reason why we argue the real near-term promise is in quantum sensing. There are room-temperature quantum sensors out there, and just removing the cooling requirements makes the technology smaller and easier to use close to people.

Law and Policy for the Quantum Age (Cambridge University Press 2022), is free and open access here: https://cup.org/3kX4JlI or you can buy a print copy for just $30 here: https://www.amazon.com/Law-Policy-Quantum-Chris-Hoofnagle/dp/1108793177

Audiobook forthcoming---we're in the proof stages now :)

If you want to learn more, I really like Doug Finke's Quantum Computing Report: https://quantumcomputingreport.com/

Many people gave us advice and helped us refine the book. In particular, IBM's team was super helpful, and IBM has some of the best educational materials and even computers you can tinker with: https://medium.com/qiskit/how-to-turn-on-your-quantum-computer-fba0a4152d92

The smaller company I have my eye on is ColdQuanta. The book explains in more detail why this company is important in the field: https://coldquanta.com/

What's our progress in quantum cryptography?

Believe it or not, Raytheon/BBN implemented a QKD network for DARPA at Harvard and Boston University back in 2003! They operated it for a few years and shut it down. https://apps.dtic.mil/sti/pdfs/ADA471450.pdf

But the more recent demonstrations out of Jian-Wei Pan's group (see https://www.science.org/doi/10.1126/science.aan3211) has kicked off reinvestment in the US and calls for new implementations (see e.g. https://chicagoquantum.org/news/toshiba-chicago-quantum-exchange-partner-new-project-economy )

It's important to know that this isn't just a US and China race! The Dutch are fantastic ( see https://www.nature.com/articles/s41586-022-04697-y ), and there are satellite QKD programs in Japan, Singapore, and Canada.

What’s currently the largest number factored by QC?

Last I checked this was February 2022 and the largest was a 13-digit number: 1,099,551,473,989. See https://www.nature.com/articles/s41534-021-00478-z

Keep in mind that these devices will have to factor a 1,300-digit number to crack modern keys! Simson and I write about this here: https://www.lawfareblog.com/quantum-cryptanalysis-hype-and-reality