On October 7, 2025, the Royal Swedish Academy of Sciences awarded the 2025 Nobel Prize in Physics to John Clarke, Michel H. Devoret, and John M. Martinis for demonstrating quantum mechanical tunneling and quantized energy states in a macroscopic electrical circuit. Their discovery revealed that quantum behavior can exist in engineered electrical systems, challenging the long-held belief that it occurs only in atoms and subatomic particles.
This breakthrough came from using superconducting circuits cooled to near absolute zero, where electrical currents exhibit quantum behavior. These circuits act like artificial atoms that can create and control quantum effects in real electrical systems, making this discovery a crucial step toward building quantum computers.
Bringing quantum physics to the macroscopic world
Quantum tunneling and energy quantization are phenomena typically observed only in atoms and tiny particles. Tunneling allows a particle to pass through an energy barrier it should not be able to cross, while energy quantization means a system can only occupy specific energy levels.
For many years, scientists believed that quantum effects do not occur on larger scales due to heat and environmental noise. However, the laureates overturned this assumption by showing that carefully engineered superconducting circuits can maintain quantum behavior when cooled near absolute zero. This was achieved using Josephson junctions, which are two superconductors separated by a thin insulating layer, allowing the circuits to behave like quantum systems with discrete energy states.
Their pioneering experiments in the mid-1980s produced the first solid evidence of macroscopic quantum tunneling in large-scale electrical circuits. This breakthrough proved that the quantum world can be controlled in engineered systems, paving the way for superconducting qubits and quantum computing technologies.
Why quantum physics matters
This discovery made it possible to control quantum behavior in electrical circuits, giving rise to the field of quantum engineering, a new approach to building technology based on quantum laws. This also laid the foundation for quantum computing, where quantum bits process information beyond the limits of traditional computers.
Quantum computing could accelerate breakthroughs across many fields, such as drug discovery, cleaner energy materials, and logistics optimization. These advances rely on the capacity of quantum processors to solve intricate problems that involve massive amounts of data and interactions. Companies such as Google and IBM are already developing early versions of these processors, marking the first steps toward a quantum future.
Beyond computing, quantum engineering uses the principles of quantum encryption to build secure communication networks. Quantum sensors are also being developed to enhance early disease detection, monitor climate conditions with extreme precision, and improve navigation in places where GPS signals fail.
John Clarke: The pioneer of quantum measurement
John Clarke joined the University of California, Berkeley in 1969 as a physics professor, where he revolutionized precision measurement through his work in Superconducting Quantum Interference Devices (SQUIDs). These ultra-sensitive sensors can detect extremely weak magnetic fields, allowing scientists to observe quantum effects at macroscopic scales.
He later established a research laboratory dedicated to exploring superconductivity and quantum behavior in macroscopic scales. In 1984-85, his team developed experimental methods that revealed macroscopic quantum tunneling and energy quantization in superconducting circuits at low temperatures.
Clarke has received numerous honors for his contributions to physics, including the Comstock Prize in Physics (1999) and the Hughes Medal (2004). In 1986, he was elected as a fellow of the Royal Society of London, and became a foreign associate of the U.S. National Academy of Sciences in 2012.
Enhancing Josephson junction performance with Q-spoiler design
Superconducting detection circuits rely on high-Q resonators to sense extremely weak magnetic signals, however, these circuits continue to oscillate after strong excitation pulses, which masks the faint responses that follow. This persistent ringing reduces measurement accuracy and delays signal detection. Maintaining rapid recovery and high sensitivity in these resonant systems has therefore been a key challenge, limiting the performance of advanced magnetic resonance and superconducting measurement technologies.
U.S. Patent. No. 4,733,182 addressed this challenge by introducing a “Q-spoiler” circuit that automatically controls the quality factor (Q) of a superconducting resonator during operation. The design uses Josephson junctions placed in series with the resonant elements so that during strong excitation pulses, the junctions become resistive and temporarily lower the Q. This rapid damping suppresses unwanted ringing that would otherwise mask weak signals.
When the excitation pulse ends, the current drops below the junctions’ critical threshold, returning them to a superconducting state and restoring the circuit’s high sensitivity. The Q-spoiler works in both parallel and series resonator configurations, improving the speed and precision of magnetic-resonance and other superconducting measurement systems.
The patent, titled “Josephson junction Q-spoiler”, was filed on March 25, 1986, and was granted on March 22, 1988. The patent lists John Clarke, Claude Hilbert, Erwin L. Hahn, and Tycho Sleator as inventors. Legal representation for the patent was handled by Clifton E. Clouse, Jr., Roger S. Gaither, and Judson F. Hightower.
Michel H. Devoret: The architect of superconducting qubits
Professor Michel H. Devoret of the University of California, Santa Barbara, has been instrumental in transforming quantum physics into practical technology. Early in his career, he joined John Clarke’s research group at UC Berkeley for his postdoctoral work, where he contributed to pioneering experiments with Josephson junctions.
In 1985, he founded the Quantronics group at CEA-Saclay to study the quantum behavior of superconducting circuits. This led to the development of the “quantronium” qubit, an early design that laid the groundwork for more stable superconducting qubits. Following this, he also joined Yale University as professor of applied physics, where he co-developed the transmon qubit with Steven Girvin and Robert Schoelkopf. This design reduced charge noise, a major source of decoherence in superconducting qubits, making them more reliable for quantum computing.
Devoret further cemented his impact on quantum technology through his pioneering work in circuit quantum electrodynamics (circuit QED), which helped lay the foundation for modern quantum computing. His contributions have earned him numerous awards, including the Fritz London Memorial Prize (2014), the Micius Quantum Prize (2021), and the Comstock Prize (2024).
Michel H. Devoret: Patenting Activity
With a total of 147 patents under 23 patent families listed under his name, Michel Devoret’s global patenting activity peaked in 2015, when research on superconducting circuits reached maturity. This coincides with the period that Devoret and Schoelkopf identified as a turning point toward scalable quantum systems, anticipating rapid progress in device-level innovation.
Nonlinear Josephson circuit to reduce frequency shifts
Superconducting circuits are difficult to control because nonlinearities in Josephson junctions can cause unwanted frequency shifts that interfere with stable operation. These shifts distort resonances and create interactions that lead to errors in measurement and signal processing. As a result, achieving precise control over circuit behavior becomes challenging, which limits the performance and scalability of superconducting quantum and microwave technologies.
To address unwanted frequency shifts in superconducting circuits, U.S. Patent. No. 11,791,818 introduces a nonlinear Josephson circuit that balances interacting elements to cancel specific nonlinearities. This design eliminates self-Kerr and cross-Kerr effects that can distort operating frequencies, allowing the circuit to maintain stable and predictable behavior. By preserving useful nonlinear interactions while removing unwanted ones, the invention improves the precision and scalability of superconducting devices used in quantum and microwave technologies.
The patent, titled “Josephson nonlinear circuit”, was filed on January 15, 2020, and was granted on October 17, 2023. The patent lists Michel Devoret, Shantanu Mundhada, Nicholas Frattini, Shruti Puri, Shyam Shankar, and Steven M. Girvin as inventors. Legal representation for the patent was handled by Wolf, Greenfield & Sacks, P.C..
John M. Martinis: The innovator of quantum supremacy
At UC Santa Barbara, Professor John M. Martinis has spearheaded research that incorporates fundamental quantum physics into large-scale device implementation. As a researcher in John Clarke’s group at UC Berkeley, he developed his expertise on superconducting electronics and precision measurement.
With this experience, he led a research group at UCSB which focused on enhancing qubit coherence and control through advances in materials and circuit design. Their research achieved record coherence times and demonstrated high-fidelity quantum gates, which are major findings that made superconducting qubits more reliable and scalable.
In 2014, Martinis became the head of Google’s Quantum AI Laboratory, where he directed the development of the Sycamore processor. In 2019, his team achieved quantum supremacy, marking a milestone in quantum computing by performing a computation beyond the reach of classical supercomputers.
For his pioneering work in quantum information science, Martinis was recognized with the Fritz London Memorial Prize (2014), alongside Michel Devoret, and the John Stewart Bell Prize (2021).
John M. Martinis: Patenting Activity
John Martinis’ patenting activity includes 140 filings across 20 patent families. His filings reached their peak in 2017, aligning with his tenure as head of Google’s Quantum Hardware Group, during the company’s intensive development phase of superconducting quantum processors.
Tapered junction wiring for reduced qubit energy loss
In superconducting qubits, the narrow metal leads that connect the Josephson junction to the capacitor can create strong electric fields near the surface. These fields can cause unwanted energy loss, making it harder for the qubit to hold its quantum state. Reducing this loss is essential for developing more stable and reliable quantum circuits.
To overcome these, U.S. Patent. No. 11,038,094 introduces a superconducting qubit design with tapered junction wiring to reduce energy loss. In this design, the metal wires connecting the Josephson junction to the capacitor gradually widen, lowering surface electric fields that normally cause dissipation and shorten qubit lifetimes. This simple geometric modification extends qubit coherence, which enhances reliability and scalability in quantum computing systems.
The patent, titled “Superconducting qubit with tapered junction wiring”, was filed on January 19, 2021, and was granted on June 15, 2021. The patent lists John M. Martinis as its sole inventor. Legal representation for the patent was handled by Fenwick & West LLP.
The future of quantum technology
Once thought to exist only in theory, quantum tunneling and energy quantization have become the foundation of a new generation of quantum technologies. The research of John Clarke, Michel Devoret, and John Martinis made it possible to harness these effects in stable and practical systems.
Their work laid the groundwork for technologies that extend the limits of computing and measurement. It has enabled quantum computers to tackle problems beyond classical systems, improved sensing tools such as SQUIDs to study magnetic fields and materials, and advanced quantum networks for faster, more secure communication.
These breakthroughs show how quantum physics can move from abstract theory to real-world innovation. As research builds on their foundations, quantum technologies are poised to redefine how we compute, communicate, and explore the physical world.
