Nobel Prize in Physics 2025 has been awarded jointly to John Clarke, Michel H. Devoret, and John M. Martinis for their groundbreaking discovery of quantum mechanical effects in macroscopic electrical circuits systems large enough to hold in one’s hand. Their experiments proved that quantum mechanical tunnelling and energy quantisation– previously known only at atomic scales- can also occur in large, visible systems.
The announcement was made by The Royal Swedish Academy of Sciences in Stockholm, Sweden.
About Discovery
Award Citation: “For discovering quantum mechanical effects that can occur in electrical circuits large enough to hold in your hand.”
The laureates demonstrated that superconducting electrical circuits could exhibit quantum tunnelling and energy quantisation, bridging the gap between microscopic quantum systems and macroscopic physical devices.
Their pioneering experiments conducted in the 1980s (1984–1985) marked a turning point in understanding how quantum phenomena can manifest at visible scales, establishing the foundation for today’s quantum technologies such as quantum computers, sensors, and advanced superconducting devices.
Background: The Quantum Scale Problem
For much of the 20th century, physicists believed that quantum mechanics governed only the microscopic world of atoms, electrons, and photons.
However, Clarke, Devoret, and Martinis challenged this notion by showing that macroscopic systems — those large enough to hold — could also exhibit quantum behaviour.
Two fundamental quantum phenomena were central to their work:
- Quantum Tunnelling:
- Refers to the ability of particles to pass through energy barriers even when they lack sufficient energy to go over them.
- Comparable to a ball rolling through a wall instead of over it.
- Energy Quantisation:
- Energy is not continuous but exists in discrete packets (quanta).
- A system can only absorb or emit energy in fixed amounts, not gradually.
Their experiments explored whether such effects could appear in large, engineered systems — and succeeded.
About the Experiment
- The team used superconducting electrical circuits cooled to near absolute zero (−273.15°C) to eliminate thermal noise.
- At the heart of the setup was the Josephson Junction — two superconducting materials separated by a thin non-conductive (insulating) barrier.
- These circuits were designed to study how billions of electrons could collectively behave as a single quantum particle.
Key Observations:
- The entire electric current flowing through the circuit demonstrated macroscopic quantum tunnelling — moving from one energy state to another through a barrier.
- The circuit absorbed or emitted energy only in discrete (quantised) amounts, confirming energy quantisation at a visible scale.
This was the first direct evidence that macroscopic systems can obey quantum rules.
Significance of the Discovery
Scientific Impact:
- Demonstrated that quantum mechanics applies not just to microscopic particles but also to engineered, macroscopic systems.
- Paved the way for new experiments studying quantum coherence and superposition in large systems.
Technological Impact:
- Provided the foundation for superconducting qubits, the fundamental units of quantum computers.
- Advanced quantum sensing technologies, next-generation transistors, and low-noise amplifiers.
- Revolutionized the design of quantum circuits, forming the backbone of modern quantum computing research.
About Quantum Mechanics
- Definition: A fundamental theory in physics describing nature at the smallest scales — atoms and subatomic particles.
- Core Principle: Matter and energy behave as both particles and waves — a concept called wave-particle duality.
- Key Quantum Features:
- Superposition: A particle can exist in multiple states simultaneously.
- Entanglement: Particles can remain connected over vast distances.
- Tunnelling: Particles can pass through barriers impossible under classical physics.
- Quantisation: Energy exists in discrete levels.
About the Laureates
| Name | Affiliation / Nationality | Contribution |
| John Clarke | University of California, Berkeley (USA) | Pioneered quantum tunnelling experiments in superconducting circuits. Pioneered SQUIDs (Superconducting Quantum Interference Devices) used for ultra-sensitive magnetic measurements. |
| Michel H. Devoret | Yale University (USA/France) | Advanced macroscopic quantum measurement and superconducting qubit development. Expert in quantum electronics and superconducting circuits. |
| John M. Martinis | University of California, Santa Barbara (USA) | Developed large-scale quantum circuits foundational for quantum computing. He is known for work on superconducting qubits; key contributor to Google’s quantum supremacy experiment. |
Institution Awarding the Prize:
- Awarded by: The Royal Swedish Academy of Sciences
- Location: Stockholm, Sweden
Scientific Importance in Modern Context
- Their findings are central to quantum information science, which underpins emerging technologies such as:
- Quantum computers – devices exploiting superposition and entanglement for computation.
- Quantum sensors – offering ultra-high precision in measurements.
- Quantum communication systems – enabling unbreakable encryption.
The 2025 Physics Nobel highlights how quantum mechanics now governs both micro and macro realms, connecting theoretical physics with practical innovation.
Key Facts
- Field: Physics
- Awarded since: 1901
- Awarding Body: The Royal Swedish Academy of Sciences
- Country of Award: Sweden
- Prize Components: Gold Medal, Diploma, and Monetary Award (~11 million SEK)
- Ceremony Date: 10th December (death anniversary of Alfred Nobel)
- 2025 Nobel Physics Laureates: John Clarke, Michel H. Devoret, John M. Martinis
- Discovery: Macroscopic quantum tunnelling and energy quantisation in superconducting circuits
- Quantum Mechanical Effects: Include superposition, entanglement, and tunneling- foundational principles of quantum physics.
- Quantum Circuits: Use superconducting materials to exhibit quantum coherence at low temperatures.