I don't want to take anything away from Bennett and Brassard, but I'd like someone to spare a word for poor Stephen Wiesner, who invented the earliest quantum information-distribution protocols as far back as the 1960s and published them before Bennett and Brassard. He also invented Oblivious Transfer (OT) which is required for multi-party computation -- although his was a quantum protocol that demonstrated some of the ideas behind QKD, not the classical protocol we call OT today [1].* Weisner was an inspiration for Bennett and Brassard, who then realized more useful systems.

While obviously this takes nothing away from BB's many later contributions (and they have extensively credited him), it's just a reminder of the randomness that goes with scientific credit. Since my PhD thesis was on OT, I like to remind people of Wiesner. He deserves a lot more credit than he gets!

* I suppose if you're a real theoretician, since OT implies MPC and MPC implies all cryptography, then perhaps Wiesner's OT implies everything that BB did subsequently. I'm not sure any of that is true (and I've since checked with an LLM and there are some no-go theorems from the 1990s that block it, so that's super interesting.)

[1] https://dl.acm.org/doi/10.1145/1008908.1008920

As a young grad student, I remember going to a talk by Bennett where he explained how a Quantum Computer allows manipulation in a 2^N dimensional hilbert space, while the outputs measurements give you only N bits of information. The trick is to somehow encode the result in the final N bits.

I felt this was a much better layman explanation of what a quantum computer does than simply saying a quantum computer runs all possible paths in parallel.

* From the announcement [0]:

ACM has named Charles H. Bennett and Gilles Brassard as the recipients of the 2025 ACM A.M. Turing Award for their essential role in establishing the foundations of quantum information science and transforming secure communication and computing.

* An accessible news excerpt via CNN science [1]

Years before emails, internet banking, cloud servers and cryptocurrency wallets, two scientists devised a way to keep secrets perfectly safe and indecipherable to eavesdropping outsiders.

Their 1984 work depended on the hidden, counterintuitive world of quantum physics, which governs the way the world works at the smallest, subatomic scale, rather than complex but theoretically breakable mathematical codes to secure data.

The insights of Charles Bennett, an American physicist who is a fellow at IBM Research, and Gilles Brassard, a Canadian computer scientist and professor at the University of Montreal, have since transformed cryptography and computing. The pair received the A.M. Turing Award on Wednesday for their groundbreaking work on quantum key cryptography.

[0] https://www.acm.org/media-center/2026/march/turing-award-202...

[1] https://edition.cnn.com/2026/03/18/science/quantum-key-crypt...

> Bennett and Brassard, with Ethan Bernstein and Umesh Vazirani, showed that in black-box setting, quantum computers would require big-omega(sqrt(n)) queries to search n entries, matching Grover's algorithm. For some reason, the popular press rarely covers these results that limit the power of quantum computing.

This is mentioned almost as a footnote, but to (layman) me seems much more important than QKD, especially from a comp sci perspective instead of a physics perspective.

The math might be beautiful, but I'm very skeptical - practical - quantum computers will ever deliver their promise.

That's 2 Turing award for the Université de Montréal in 6 years. Sadly, I never had those 2 teachers during my years there!

I did see Gilles' lunch talks though, it was really insightful!

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Really curious, not a critique: apart from the idea of the possibility of intrusion detection due to the quantum nature of the communication link, what is special about the protocol that is mentioned?

Coincidentally, the same people also recently received the Science Fiction Award 2025!

Well deserved and much needed recognition in quantum key cryptography, for once not a single mention of "AI" anywhere.

Congratulations to Charles Bennett and Gilles Brassard.

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