Turing Award Goes to Quantum Science for the First Time as Bennett and Brassard Win Computing's Highest Honor

The ACM announced on March 18 that Charles H. Bennett and Gilles Brassard are the recipients of the 2025 A.M. Turing Award, recognizing their foundational contributions to quantum information science. The award, which carries a $1 million prize funded by Google, marks the first time computing’s most prestigious honor has been given for work rooted in quantum physics.

Bennett, an IBM Fellow and research scientist at the IBM Thomas J. Watson Research Center in Yorktown Heights, New York, has spent more than five decades at the company. Brassard is a professor at the Université de Montréal. According to IBM’s announcement, the ACM cited the pair “for their essential role in establishing the foundations of quantum information science and transforming secure communication and computing.”

A Meeting at the Beach

The collaboration began at a conference in Puerto Rico in October 1979. As recounted in Quanta Magazine, Bennett approached Brassard while swimming at a beachfront hotel and described an unpublished idea by their late colleague Stephen Wiesner: quantum money, a scheme that would exploit quantum mechanics to make currency physically impossible to counterfeit. Brassard recalled: “I was trapped, so I listened politely.” Within ten minutes, they had outlined ideas for their first collaborative paper.

Wiesner’s insight was that measuring a quantum state inevitably disturbs it, making perfect copying impossible. Bennett and Brassard recognized that this property could be harnessed not just for unforgeable banknotes but for an entirely new approach to secure communication.

BB84 and the Birth of Quantum Cryptography

In 1984, Bennett and Brassard introduced what is now known as the BB84 protocol, the first practical scheme for quantum key distribution. The protocol allows two parties to establish a shared secret encryption key using the polarization states of individual photons. Its security rests not on mathematical assumptions that a future computer might break, but on the laws of physics themselves: any eavesdropper who intercepts the photons inevitably disturbs their quantum states, alerting the legitimate parties to the intrusion.

According to IBM’s announcement, the team built and demonstrated the first working BB84 apparatus in 1989 using custom equipment assembled from mirrors, polarizers, and photon detectors. That proof-of-concept transmitted a quantum key across 30 centimeters of open air. As Quanta Magazine reports, that demonstration has since inspired satellite-based quantum key distribution systems operating over distances exceeding 1,000 kilometers.

Quantum Teleportation

In 1993, Bennett and Brassard, together with four collaborators, introduced quantum teleportation: a protocol demonstrating that an unknown quantum state can be transmitted between distant parties using quantum entanglement and classical communication. The technique does not transmit matter or information faster than light, but it showed that entanglement — a phenomenon Einstein famously dismissed as “spooky action at a distance” — could serve as a practical computational resource.

Quantum teleportation has since become a fundamental building block in quantum computing and quantum networking architectures, underpinning proposals for distributed quantum computation and long-distance quantum communication.

From the Margins to the Mainstream

Bennett and Brassard’s early work unfolded largely outside the mainstream of both physics and computer science. Bennett reflected on the period in Quanta Magazine: “In those days, it was nobody’s day job.” John Preskill, a physicist at Caltech, observed that the pair “helped to set the culture for this group, which was kind of on the fringes of both physics and computer science at the time.”

The field’s trajectory changed sharply in 1994 when Peter Shor published his quantum factoring algorithm, demonstrating that a sufficiently powerful quantum computer could break the public-key cryptographic systems underpinning internet security. Brassard noted the impact: “Shor’s algorithm made our idea unavoidable.”

That result catalyzed decades of investment in quantum computing hardware, post-quantum cryptography, and quantum networking. Bennett, reflecting on the broader arc of their work in Quanta Magazine, suggested that quantum techniques may ultimately offer defenses against the very threats quantum computers pose: “It might be a way where there’s a quantum rescue from the quantum disaster of Shor’s algorithm.”

IBM’s Seventh Turing Laureate

Bennett’s recognition makes him IBM’s seventh Turing Award recipient. Jay Gambetta, IBM’s Research Director, said in the company’s statement: “Charlie is an inspiration to all of us. That insight, and the decades of work that followed, helped lay the intellectual foundation for one of the most important scientific frontiers of our time.”

Bennett credited IBM’s research environment for enabling the kind of cross-disciplinary exploration that the work required. “IBM was an ideal place to do this kind of research because you had people working on the fundamental physics of computing,” he said, according to IBM’s announcement. “I could wander down the hall and talk to many people about fundamental ideas.”

The Turing Award, often described as the Nobel Prize of computing, has previously recognized achievements in areas including cryptography, artificial intelligence, and programming language design. The extension of the prize to quantum information science reflects the field’s evolution from a theoretical curiosity into an active area of engineering and commercial investment, with governments and corporations worldwide committing billions of dollars to quantum computing, quantum networking, and post-quantum security infrastructure.