Quantum Computing near a Tipping Point?

Written by: Stephen Hsu

Primary Source: Information Processing

I received an email from a physicist colleague suggesting that we might be near a “tipping point” in quantum computation. I’ve sort of followed quantum computation and quantum information as an outsider for about 20 years now, but haven’t been paying close attention recently because it seems that practical general purpose quantum computers are still quite distant. Furthermore, I am turned off by the constant hype in the technology press…

But perhaps my opinion is due for an update? I know some real quantum computing people read this blog, so I welcome comments.

Here’s part of what I wrote back:

I’m not sure what is meant by “tipping point” — I don’t think we know yet what qubit technology can be scaled to the point of making Shor’s Algorithm feasible. The threat to classical cryptography is still very far off — you need millions* of qubits and the adversary can always just increase the key length; the tradeoffs are likely to be in favor of the classical method for a long time.

Noisy quantum simulators of the type Preskill talks about might be almost possible (first envisioned by Feynman in the Caltech class he gave in the 1980s: Limits to Computation). These are scientifically very interesting but I am not sure that there will be practical applications for some time.

* This is from distant memory so might not be quite right. The number of ideal qubits needed would be a lot less, but with imperfect qubits/gates and quantum error-correction, etc., I seem to remember a result like this. Perhaps millions is the number of gates, not qubits? (See here.)

These are the Preskill slides I mentioned — highly recommended. John Preskill is the Feynman Professor of Theoretical Physics at Caltech :-)

Here’s a summary of current and near-term hardware capability:

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Stephen Hsu
Stephen Hsu is vice president for Research and Graduate Studies at Michigan State University. He also serves as scientific adviser to BGI (formerly Beijing Genomics Institute) and as a member of its Cognitive Genomics Lab. Hsu’s primary work has been in applications of quantum field theory, particularly to problems in quantum chromodynamics, dark energy, black holes, entropy bounds, and particle physics beyond the standard model. He has also made contributions to genomics and bioinformatics, the theory of modern finance, and in encryption and information security. Founder of two Silicon Valley companies—SafeWeb, a pioneer in SSL VPN (Secure Sockets Layer Virtual Private Networks) appliances, which was acquired by Symantec in 2003, and Robot Genius Inc., which developed anti-malware technologies—Hsu has given invited research seminars and colloquia at leading research universities and laboratories around the world.
Stephen Hsu

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