Congrats to Bennett and Brassard on the Turing Award!
I’m on a spring break vacation-plus-lecture-tour with Dana and the kids in Mexico City this week, and wasn’t planning to blog, but I see that I need to make an exception. Charles Bennett and Gilles Brassard have won the Turing Award, for their seminal contributions to quantum computing and information including the BB84 quantum key distribution scheme. This is the first-ever Turing Award specifically for quantum stuff (though previous Turing Award winners, including Andy Yao, Leslie Valiant, and Avi Wigderson, have had quantum among their interests).
As a practical proposal, BB84 is already technologically feasible but has struggled to find an economic niche, in a world where conventional public-key encryption already solves much the same problem using only the standard Internet—and where, even after scalable quantum computers become able to break many of our current encryption schemes, post-quantum encryption (again running on the standard Internet) stands ready to replace those schemes. Nevertheless, as an idea, BB84 has already been transformative, playing a central role in the birth of quantum information science itself. Beyond BB84, Bennett and Brassard have made dozens of other major contributions to quantum information science, with a personal favorite of mine being the 1994 BBBV (Bennett Bernstein Brassard Vazirani) paper, which first established the limitations of quantum computers at solving unstructured search problems (and indeed, proved the optimality of Grover’s algorithm even before Grover’s algorithm had been discovered to exist).
While I take my kids to see Aztec artifacts, you can learn much more from Ben Brubaker’s Quanta article, to which I contributed without even knowing that it would be about Bennett and Brassard winning the Turing Award (info that was strictly embargoed before today). It’s an honor to have known Charlie and Gilles as well as I have for decades, and to have been able to celebrate one of their previous honors, the Wolf Prize, with them in Jerusalem. Huge congrats to two of the founders of our field!
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Comment #1 March 18th, 2026 at 12:39 pm
I actually admire Bennett even more for other work he’s done – about the Maxwell demon/Szilard/Landauer stuff, and for the Bennett Acceptance Ratio (BAR).
Obviously a chart-topper, not a one-hit wonder!
Comment #2 March 18th, 2026 at 1:31 pm
Congratulations to this year’s Turing Award laureates!
According to La Presse, Gilles Brassard will participate via videoconference, explaining: “As long as the little dictator is in power, I’m not going to the United States under any circumstances—not even for that.”
Comment #3 March 18th, 2026 at 3:21 pm
As a relative nobody in the field, I am thrilled to have been able to meet both of them. Bennett was my first professional hero. Both were quite delightful and easily approachable for a lowly student (I met Bennett in college and Brassard in grad school). I remember Gilles saying that the first experimental realization of BB84 made a loud thunk whenever the polarization changed, so it was provably unconditionally secure against any deaf eavesdropper! Congrats to both of them!
Comment #4 March 19th, 2026 at 5:00 pm
Does not BB84 have a problem with authenication?
Comment #5 March 19th, 2026 at 6:40 pm
Have a nice holiday, Scott. When you get back, I recommend that you get into optical computing. I say that because because after nearly 60 years, quantum computing just isn’t going anywhere. Don’t waste your life. Hup hup1
Comment #6 March 19th, 2026 at 7:42 pm
Congrats to Bennett and Brassard! I’ve never met Bennett but I knew Brassard slightly a long time ago (I was a newbie undergrad at the time). I was familiar with big-O notation before I met him, but he had a handout on the topic for a class he was teaching, and it was the first time I saw that it made any mathematical sense, and that CS was an actual mathematical topic rather than an area where one could use mathematical tools. Basically he defined O(f) as the set of functions g such that blah blah, i.e. it was precise rather than handwavy. He similarly had big-Omega and big-Theta. It was an eye opening moment. Lots of people were using O to mean Theta, fwiw.
Meanwhile, something off topic from the Turing award but quantum related. I’ve heard of the Butterfly Effect described as a butterfly flapping its wings in Brazil affecting a thunderstorm in Texas or whatever. I.e. the effect is propagated through collisions of air molecules in chaotic motion, so both endpoints in the story are on Earth. I’m wondering if it’s actually cosmic in scale because of quantum entanglement. Can it be that a butterfly-oid organism flapping its wings on the planet Zaldor-Q23 in the Andromeda Galaxy collapses some quantum states that are entangled with those of air molecules in Texas, affecting the Texas weather in sort of the same way?
Comment #7 March 19th, 2026 at 10:29 pm
John Duffield #5: Not interested in a debate. Only want to know: if fault-tolerant Shor’s algorithm is used to factor large numbers in the relatively near future, will you come back here to admit you were wrong, or will you have some way to explain away even that?