- Clarke, Devoret, and Martinis proved quantum tunneling works at macroscopic scale.
- Their 1984-1985 experiments used superconducting Josephson junctions at UC Berkeley.
- The discovery laid the foundation for modern superconducting quantum computers.
John Clarke had spent years exploring quantum tunneling in superconductors when two young researchers joined his Berkeley lab in the early 1980s.
Michel Devoret arrived from Paris as a postdoctoral fellow. John Martinis was working toward his doctorate. Together, the three set out to answer a question most physicists considered settled.
When Quantum Tunneling Was Just Theory
In the 1980s, quantum mechanics described a microscopic world with almost no practical applications. Particles could tunnel through barriers they lacked the energy to cross, but only at the atomic scale. The idea that billions of particles might tunnel together seemed absurd.
Clarke's group built a superconducting circuit incorporating a Josephson junction. They were working from theoretical predictions by Anthony Leggett, who would later win his own Nobel Prize for explaining superfluid helium.
The challenge was eliminating enough environmental noise to see the quantum signal clearly.
Previous experiments had shown hints. Clarke, Devoret, and Martinis wanted certainty.
What is a Josephson junction?
A Josephson junction places a thin insulating layer between two superconductors. At temperatures near absolute zero, electron pairs called Cooper pairs move through the superconductor in lockstep. Under the right conditions, these pairs can tunnel collectively through the insulating barrier as if it were not there.
A Current That Passes Through Walls
Their 1984 and 1985 experiments at UC Berkeley produced results that left no room for doubt. By measuring every classical parameter of their circuit independently, they could compare observed tunneling rates directly against theoretical predictions, with no adjustable parameters.
The Cooper pairs in their superconductor behaved as a single quantum object filling the entire circuit.
That object tunneled through a barrier, and it absorbed and emitted energy in discrete packets, just as quantum mechanics predicted.
The chip was small enough to hold in one hand.
The implications were not.
To put it mildly, it was the surprise of my life.
John Clarke, at the Nobel Prize announcement
From Berkeley Lab to Quantum Computers
The discovery moved quantum physics from abstraction into engineering. A current that can tunnel can also exist in two states simultaneously, which is precisely what a qubit needs.
Four decades later, superconducting qubits built on Josephson junctions form the core of quantum computers at Google, IBM, and other technology companies. The same principles appear in experiments searching for dark matter particles.
More On Quantum Computing
Advanced Quantum Simulation Could Reveal Cosmic Mysteries
We've entered an era where quantum simulations outrun what we can verify. Physicists just have to trust the process.
→Science communicator Sabine Hossenfelder, reviewing the prize on her YouTube channel, noted the Nobel committee chose to honor the foundational technology rather than quantum computing itself. Theoretical physicist David Deutsch, widely regarded as a pioneer of quantum computing theory, was passed over.
The 2025 Nobel Prize recognized a professor, a postdoc, and a graduate student who proved that quantum mechanics does not stop at the atomic scale.
They shared the 11 million Swedish kronor equally.
Clarke is now professor emeritus at Berkeley. Devoret holds positions at Yale and as chief scientist for quantum hardware at Google. Martinis serves as chief technology officer at Qolab in Los Angeles.
Back in the 1980s, physicists argued all night over the interpretation of quantum mechanics. They still do, Hossenfelder observed.
Only now they do it in a clean room.
Sources
- Primary Source: Nobel Prize in Physics 2025 Press Release (NobelPrize.org)
- Additional Context:
- The 2025 Physics Nobel Prize: Macroscopic Quantum Tunneling (Sabine Hossenfelder, YouTube)
- John Clarke awarded 2025 Nobel Prize in Physics (Berkeley News)
- The prize at the end of the quantum tunnel (Nature Physics)
Fact Check: Claim-by-Claim Verification Verified
The article accurately reports the 2025 Nobel Prize in Physics awarded to John Clarke, Michel Devoret, and John Martinis for demonstrating macroscopic quantum tunneling in superconducting circuits using Josephson junctions, with all key facts matching official sources.
Commentary
- Article appropriately simplifies complex physics for popular audience without factual errors; mentions theoretical groundwork by Anthony Leggett (2003 Nobel) correctly.
- Sabine Hossenfelder's observation on prize focus is contextual commentary, not a verifiable claim requiring fact-check.
Sources used for verification
Academic/Peer-reviewed:
- Nobel Prize in Physics 2025 Press Release - NobelPrize.org
- John Clarke awarded 2025 Nobel Prize - Berkeley.edu
- Yale's Michel H. Devoret wins 2025 Nobel Prize - Yale.edu
- John Clarke Wins 2025 Nobel Prize - LBL.gov
Other reliable sources:
- John Clarke, Michel Devoret and John Martinis win 2025 Nobel - PhysicsWorld.com
- Nobel Prize: Quantum Tunneling on a Large Scale - APS.org
Fact-checked by Perplexity Sonar Pro on 2026-03-11
