The 2025 Nobel Prize in Physics recognizes the discovery of macroscopic quantum tunneling in electrical circuits.
This story will be updated with a longer explanation of the Nobel-winning work on Thursday, 9 October.
Running up against a barrier, a classical object bounces back, but a quantum particle can come out the other side. So-called quantum tunneling explains a host of phenomena, from electron jumps in semiconductors to radioactive decays in nuclei. But tunneling is not limited to subatomic particles, as underscored by this year’s Nobel Prize in Physics. The prize recipients—John Clarke from the University of California, Berkeley; Michel Devoret from Yale University; and John Martinis from the University of California, Santa Barbara—demonstrated that large objects consisting of billions of particles can also tunnel across barriers [1– 3]. Using a superconducting circuit, the physicists showed that the superconducting electrons, acting as a collective unit, tunneled across an energy barrier between two voltage states. The work thrust open the field of superconducting circuits, which have become one of the promising platforms for future quantum computing devices.
The Nobel Prize in Physics was awarded to three scientists on Tuesday for discovering that a bizarre barrier-defying phenomenon in the quantum realm could be observed on an electrical circuit in our classical world.
The discovery, which involved an effect called quantum tunneling, laid the foundations for technology now being used by Google and IBM aiming to build the quantum computers of the future.
Here is what you need to know about the Nobel-winning work by John Clarke of the UK, Frenchman Michel Devoret and American John Martinis.
Briton John Clarke, Frenchman Michel Devoret and American John Martinis won the Nobel Prize in Physics on Tuesday for putting quantum mechanics into action and enabling the development of all kinds of digital technology from cellphones to a new generation of computers.
The Nobel jury noted that their work had “provided opportunities for developing the next generation of quantum technology, including quantum cryptography, quantum computers and quantum sensors”
Quantum mechanics describes how differently things work on incredibly small scales.
From computer chips to quantum dots—technological platforms were only made possible thanks to a detailed understanding of the used solid-state materials, such as silicon or more complex semiconductor materials. This understanding also includes being able to identify and control irregularities in the crystal lattice of such materials.
If, for example, an atom is missing in the lattice structure of the crystals, a single electron and thus an electric charge can become trapped there. Such charge traps generate electromagnetic noise that limits the functionality of these materials. However, it is extremely difficult to locate these charge traps on an atomic scale.
Researchers from the “Integrated Quantum Photonics” group at the Department of Physics at Humboldt-Universität zu Berlin (HU) and the “Joint Lab Diamond Nanophotonics” at the Ferdinand-Braun-Institut, led by Prof. Dr. Tim Schröder, have developed a new sensor that can detect such individual electrical charges more precisely than ever before.
Introduction.
Grounded in the scientific method, it critically examines the work’s methodology, empirical validity, broader implications, and opportunities for advancement, aiming to foster deeper understanding and iterative progress in quantum technologies. ## Executive Summary.
This work, based on experiments conducted in 1984–1985, addresses a fundamental question in quantum physics: the scale at which quantum effects persist in macroscopic systems.
By engineering a Josephson junction-based circuit where billions of Cooper pairs behave collectively as a single quantum entity, the laureates provided empirical evidence that quantum phenomena like tunneling through energy barriers and discrete energy levels can manifest in human-scale devices.
This breakthrough bridges microscopic quantum mechanics with macroscopic engineering, laying foundational groundwork for advancements in quantum technologies such as quantum computing, cryptography, and sensors.
Overall strengths include rigorous experimental validation and profound implications for quantum information science, though gaps exist in scalability to room-temperature applications and full mitigation of environmental decoherence.
Framed within the broader context, this award highlights the enduring evolution of quantum mechanics from theoretical curiosity to practical innovation, building on prior Nobel-recognized discoveries like the Josephson effect (1973) and superconductivity mechanisms (1972).
A major question in physics is the maximum size of a system that can demonstrate quantum mechanical effects. This year’s Nobel Prize laureates conducted experiments with an electrical circuit in which they demonstrated both quantum mechanical tunnelling and quantised energy levels in a system big enough to be held in the hand.
Quantum mechanics allows a particle to move straight through a barrier, using a process called tunnelling. As soon as large numbers of particles are involved, quantum mechanical effects usually become insignificant. The laureates’ experiments demonstrated that quantum mechanical properties can be made concrete on a macroscopic scale.
In 1984 and 1985, John Clarke, Michel H. Devoret and John M. Martinis conducted a series of experiments with an electronic circuit built of superconductors, components that can conduct a current with no electrical resistance. In the circuit, the superconducting components were separated by a thin layer of non-conductive material, a setup known as a Josephson junction. By refining and measuring all the various properties of their circuit, they were able to control and explore the phenomena that arose when they passed a current through it. Together, the charged particles moving through the superconductor comprised a system that behaved as if they were a single particle that filled the entire circuit.
The new map of the Universe’s expansion history released by the DESI Collaboration offers hints at a breakdown of the standard model of cosmology.
For nearly a century, we have known that our Universe is expanding. For the past quarter-century, we have also known that this expansion is accelerating, a discovery that earned the 2011 Nobel Prize in Physics [1, 2]. But what is the mysterious “dark energy” that drives this acceleration? The simplest explanation involves what Einstein dubbed a “cosmological constant” (Λ) and implies that dark energy is a constant energy inherent to spacetime itself. This idea is the cornerstone of the standard model of cosmology, the Λ cold dark matter (ΛCDM) model, which for decades has consistently explained all available astronomical observations. Now high-precision measurements of the Universe’s expansion history are putting this model to its most stringent test yet. The Dark Energy Spectroscopic Instrument (DESI) has created a cosmic map of unprecedented scale (Fig. 1) [3–9].
Optical lattice clocks are emerging timekeeping devices based on tens of thousands of ultracold atoms trapped in an optical lattice (i.e., a grid of laser light). By oscillating between two distinct quantum states at a particular frequency, these atoms could help to measure time with much higher precision than existing clocks, which would be highly advantageous for the study of various fundamental physical processes and systems.
Researchers at JILA, National Institute of Standards and Technology and University of Chicago recently developed an optical lattice clock based on strontium atoms that was keeping time with remarkable precision and accuracy. The new strontium optical clock, introduced in a paper published in Physical Review Letters, could open new possibilities for research aimed at testing variations in fundamental physics constants and the timing of specific physical phenomena.
“We have been pushing the performance of the optical lattice clock,” Kyungtae Kim, first author of the paper, told Phys.org. “Thanks to a major upgrade from 2019 to 2021, we demonstrated record differential frequency measurement capability, reaching a resolution of gravitational redshift below the 1-mm scale, as well as record accuracy (until this July) as a frequency standard. To push the performance further, one needs to understand and model the current system. This work provides a detailed snapshot of the clock’s current operation.”
Ultrathin structures that can bend, focus, or filter light, metasurfaces are reshaping how scientists think about optics. These engineered materials offer precise control over lights behavior, but many conventional designs are held back by inefficiencies. Typically, they rely on local resonances within individual nanostructures, which often leak energy or perform poorly at wide angles. These shortcomings limit their usefulness in areas like sensing, nonlinear optics, and quantum technologies.
A growing area of research looks instead to nonlocal metasurfaces, where interactions between many elements create collective optical effects. These collective behaviors can trap light more efficiently, producing sharper resonances and stronger interactions with matter. One of the most promising possibilities in this field is the development of photonic flatbands, where resonant behavior stays uniform across a wide range of viewing angles.
Another is creating chiral responses, which allow devices to distinguish between left-and right-handed circularly polarized light. Until now, however, achieving both flatband and chiral behavior with high efficiency on a single platform has remained a major challenge.