2025 Nobel Prize in Physics goes to quantum mechanical tunneling discovery

Back in 1984 and 1985, Professor John Clarke (UC Berkeley), Professor Michael H. Devoret (Yale and UC Santa Barbara), and Professor John M. Martinis (UC Santa Barbara) ran a series of experiments with an electronic circuit built of superconductors—components that conduct a current without electrical resistance. Within the circuit, they kept the superconducting components separated by a thin layer of nonconductive material, a.k.a. a Josephson junction.

After refining and measuring all various properties of their circuit, the researchers controlled and explored the phenomena they encountered while passing a current through it. They observed that charged particles moving through the superconductor behaved as if they were a single particle filling the entire circuit.

Their system was initially in a state in which current flows without any voltage—and trapped within this state. It showed its quirky quantum character by managing to escape the zero-voltage state through tunneling, which was detected by the appearance of a voltage.

This system also behaved as predicted by quantum mechanics, which enables a particle to move straight through a barrier via tunneling—it’s quantized (only absorbs/emits a certain amount of energy).

“It is wonderful to be able to celebrate the way that century-old quantum mechanics continually offers new surprises,” says Olle Ericksson, chair of the Nobel Committee for Physics.

This work recognized by the 2025 Nobel Prize in Physics laid the foundation for developing the next generation of quantum technology, such as quantum cryptography, quantum communications, quantum computers, and quantum sensors.