The 2025 Physics Nobel Prize: Quite A Surprise

The 2025 Nobel Prize in Physics was awarded for macroscopic quantum tunneling—an effect that lets a system behave quantum mechanically even when it involves an enormous number of particles. That leap matters because it turned quantum physics from an abstract, hard-to-test framework into something engineers could eventually build with, helping seed the modern era of quantum technology.

The prize went to John Clark, Michel Devoret, and John Martinis. Much of the work traces back to a landmark 1985 paper demonstrating that macroscopic quantum tunneling is real. The underlying idea is familiar from quantum tunneling: a particle can pass through an energy barrier even when it lacks the classical energy to do so. Without quantum behavior, the particle would remain trapped. With quantum properties, it can “leak” through the barrier.

A well-known example of tunneling is electron tunneling microscopy, where electrons tunnel into a microscope tip to probe surfaces atom by atom. But that effect is tiny for single electrons. Clark, Devoret, and Martinis showed that tunneling can also occur for large collections of particles—specifically, for currents in superconducting wires. While “macroscopic” sounds like something as large as everyday objects, a current in a superconducting circuit still represents millions of electrons acting collectively. In their experiments, the collective current could tunnel across a literal gap in the circuit’s energy landscape.

Superconductivity is essential. The electrons must behave as one coherent quantum state; otherwise the effect disappears. That requirement forces experiments to run at temperatures near absolute zero, where thermal noise cannot wash out the quantum behavior. As the wires are cooled, the current’s behavior becomes impossible to reproduce without quantum effects—evidence that the tunneling is genuinely quantum rather than a classical artifact.

The downstream impact is the real reason the Nobel committee’s choice resonates. Over the following decades, the ability to engineer and control quantum behavior in superconducting circuits helped move quantum physics into the “microchip range.” That shift underpins today’s superconducting-circuit quantum computing, where a controllable current can represent states needed for qubits. The transcript notes that current quantum computers used by major industry players build on the conceptual lineage of the 1980s experiments, even if the exact hardware differs.

The work also feeds other research directions, including experiments that look for dark matter particles that might disrupt superconducting currents. Even so, the most significant legacy described here is cultural and practical: quantum mechanics became experimentally tangible, changing how physicists think about what quantum theory can deliver.

The discussion ends with a note of disappointment from a theoretical-leaning perspective: many expected a Nobel for theoretical quantum computing. The transcript also highlights that Nobel decisions are made by the Royal Swedish Academy of Sciences, meaning individual committee influence can shape scientific recognition. In the meantime, science communication is promoted via Nautilus, framed as a trusted source for broad, contextual coverage across disciplines.