Discoveries that enabled quantum computers win the Nobel Prize in physics

For bringing quantum effects to a scale once thought impossible, three physicists have won the 2025 Nobel Prize in physics.

In the 1980s, John Clarke, Michel Devoret and John Martinis demonstrated the effects of quantum tunneling and energy quantization in an electric circuit. That phenomenon involved billions of electrons, and took place on a chip big enough to hold in one’s hand, running counter to the expectation that quantum effects are constrained to the realm of individual atoms.

“The basis of quantum computing relies to quite an extent on our discovery,” said Clarke, of the University of California, Berkeley during the Oct. 7 announcement by the Royal Swedish Academy of Sciences. He splits the 11 million Swedish krona (over $1.1 million) prize with Martinis, of UC Santa Barbara, and Devoret, of Yale University and UC Santa Barbara.

Since the discovery, tech companies and researchers around the world have used similar circuits as the quantum bits, or qubits, that make up quantum computers.

Quantum tunneling is a counterintuitive process by which a quantum system passes through a seemingly impenetrable barrier, like a ball rolled partway up a hill somehow appearing on the other side. The researchers demonstrated this effect in a device called a Josephson junction. It consists of a superconductor, a material that conducts electricity without resistance, sandwiching an insulator.

In a 1985 paper in Physical Review Letters, the three reported that, when chilled to very cold temperatures, the circuit could tunnel between a state in which there is no voltage across the junction and one in which there is a voltage. And in another paper that same year, they showed that the circuit absorbed energy in discrete chunks, what’s known as quantization.

“It’s the foundation for why superconducting qubits work,” says physicist Andreas Wallraff of ETH Zurich, who works in the field. “The thing that was special is that they not only did this early experiment but continued to push the field forward throughout the years in different ways.”

For example, Martinis was a central figure in the quest to demonstrate that a quantum computer could perform a calculation that would be out of reach for a traditional computer. In 2019, when he was the leader of Google’s quantum computing effort, his team claimed, controversially, to have hit that benchmark. Jockeying for the milestone has continued since.

Quantum computers’ power rests in the rules of quantum mechanics, which differ from those that apply to everyday objects. That gives the computers the potential to perform feats such as breaking the standard type of encryption used to secure internet communications. The prize comes during a yearlong celebration of quantum mechanics, in honor of its 100th anniversary.