Credits: Montage by Nagae Iku (Wikimedia Commons), composed from images credited to: John Martinis (cropped).jpg, John Clarke (physicist) 2025 (4×5).png, Michel H. Devoret 2017 190×180.jpg / Wikimedia Commons — CC BY 4.0.
In Stockholm on October 7, 2025, the Royal Swedish Academy of Sciences honors John Clarke, Michel H. Devoret and John M. Martinis for revealing, in superconducting circuits, quantum tunneling and energy quantization at the macroscopic scale. Their foundational experiments of the 1980s paved the way for transmon and derivative superconducting qubits and applications in computing, sensing and cybersecurity, laying the groundwork for a new industry.
Nobel Prize In Physics 2025: What The Announcement Means
On October 7, 2025, the Royal Swedish Academy of Sciences awarded the Nobel Prize in Physics to John Clarke, Michel H. Devoret and John M. Martinis, awarding the nobel prize physics 2025 to laureates John Clarke, Michel H. Devoret and John M. Martinis. Reason: having shown, using superconducting circuits at the heart of quantronics, that quantum phenomena, quantum tunneling and energy quantization, manifest at a macroscopic scale. In plain terms: electrical setups become genuine “artificial atoms,” observable and controllable in the lab. The Academy cites concrete prospects for the next generation of quantum technologies: computers, sensors and cryptography.
Official affiliations (Nobel press release): John Clarke (University of California, Berkeley); Michel H. Devoret (Yale University, New Haven, United States); John M. Martinis (University of California, Santa Barbara).
“Quantum physics in action”: behind this phrase is the idea that the phase of a Josephson junction behaves quantum mechanically. This key element of superconducting circuits is a macroscopic quantity with energy quantization into discrete levels. Moreover, it allows the possibility to cross a barrier via quantum tunneling.
For the public, the most telling image remains that of a wall being crossed. Indeed, a marble lacks the energy to jump the obstacle. However, in the quantum realm, it appears on the other side with a small probability. The laureates translated this intuition into circuits, creating a lineage leading to transmon and derivative superconducting qubits.
Nobel Prize In Physics 2025 Laureates: What They Demonstrated
In the mid-1980s, two experiments were landmark. In a current-biased Josephson junction, the Martinis–Devoret–Clarke team measured the escape rate from the zero-voltage to the non-zero-voltage regime: a macroscopic quantum tunneling. A few weeks earlier, the same researchers reported the first observation of quantized energy levels for the phase. This phase is a collective variable of a circuit. These results established that a macroscopic degree of freedom follows quantum laws.
Milestones:
- October 7, 1985: demonstration of energy-level quantization in a Josephson junction under microwaves. — Phys. Rev. Lett. 55(15): 1543–1546, published October 7, 1985 (Energy-Level Quantization in the Zero-Voltage State of a Current-Biased Josephson Junction).
- October 28, 1985: measurement of macroscopic quantum tunneling in the underdamped regime. — Phys. Rev. Lett. 55(18): 1908–1911, published October 28, 1985 (Measurements of Macroscopic Quantum Tunneling in a Josephson Junction).
These papers became classics and seeded an entire field: superconducting quantum circuits, nonlinear oscillators and readout methods. Later, they influenced error-correcting codes applied to resonators and so-called “cat” qubits.
How A Circuit Becomes An “Artificial Atom”
The Josephson junction, two superconductors separated by a nanometer-scale barrier, is the basic building block. At very low temperature, the phase of the collective wavefunction plays the role of a coordinate. The washboard potential creates wells where the phase is trapped with discrete levels. Two mechanisms govern escape from the well:
- Thermal activation (classical), dominant at “high” temperature.
- Quantum tunneling (quantum) at low temperature, which causes a stochastic jump to the conducting state (appearance of a measurable voltage).
By driving the circuit with microwaves, one induces resonant transitions between levels. The signature: a change in the escape rate when the supplied energy matches the gap between two levels. It was this spectroscopy that, in 1985, provided the experimental proof.
From Labs To Superconducting Qubits
The lineage to superconducting circuits is direct. Qubits for superconducting quantum computing (charge, phase, flux) arise from these ideas; they evolved into the transmon, a design that reduces charge noise by shunting the junction with a large capacitance.
Two notions link them:
- Josephson nonlinearity: it creates non-equidistant levels, a requirement to address a qubit (states |0⟩ and |1⟩) selectively within an oscillator.
- Microwave engineering: cavities, transmission lines, tunable couplings and parametric amplifiers organize readout and control at the gigahertz scale.
In industry, these qubits have proliferated. John M. Martinis led the Google Quantum AI effort until 2020. Michel H. Devoret, a Yale figure, trained a generation of researchers on superconducting qubits and cat qubits. John Clarke, at Berkeley, advanced SQUIDs, magnetometers of extreme sensitivity, and widely inspired detection architectures.
What Is This Nobel For? Applications And Stakes
- Quantum computing: superconducting processors targeting hybrid algorithms (chemistry, optimization, materials). Debates focus on decoherence, scaling and energy cost.
- Sensors: SQUIDs (superconducting quantum interference devices) detect infinitesimal magnetic fields, useful in neuroimaging, geophysics or fundamental physics (searches for the axion).
- Cybersecurity: post-quantum cryptography (PQC) is classical but designed to resist quantum computers; quantum key distribution (QKD) and hardware quantum random number generators (QRNGs) rely on measurable physical quantum phenomena.
Ecological impact: milli-kelvin cryostats and associated electronics have a real energy cost. Efficiency will require noise-tolerant architectures, more efficient refrigerators, and use cases where the gain (optimization, low-carbon materials) offsets the footprint. As an order of magnitude, a 4 K cryostat consumes about 7 kW of electricity, and dilution refrigerators reaching the milli-kelvins can exceed that figure depending on architecture (source: Bluefors, 2024).
Portrait: From Saclay To Yale, The Path Of A French Pioneer
Michel H. Devoret, born in 1953 in Paris, trained in France, built bridges between Saclay, Berkeley and Yale. Co-author of the 1985 experiments, he helped turn superconducting circuits into a toolbox for quantum mechanics: electron pumps, Josephson amplifiers, transmon, cat qubits. His trademark: a pedagogy of “quantronics”, the landscape where currents and voltages become quantum.
At Berkeley, John Clarke, a SQUID pioneer, has long shaped detection and instrumentation. At Santa Barbara, John M. Martinis turned the proof of principle into experimental platforms, up to industrial prototypes.
France In The Race
The distinction resonates in France, where the quantum ecosystem has organized: national programs, European funding, a rise of startups (analog computing, simulators, sensors). Education, schools and labs, remains an asset, but the challenge is scaling up: talent, cryogenic supply chains, low-noise electronics, and interoperability with the cloud.