The 2025 Nobel Prize in Physics honors three quantum physicists: John Clarke, Michel H. Devoret and John M. Martinis, for their study of quantum mechanics in a macroscopic electrical circuit.
Since the award announcement, cheers and enthusiasm surrounded these awardees’ home institutions in Berkeley, Santa Barbara and New Haven.
The awarding of this prestigious prize for pioneering research in quantum physics coincides with the centenary of the birth of quantum mechanics, a revolutionary scientific theory that forms the basis of modern physics.
Quantum mechanics was originally formulated to explain and predict the complex behavior of atoms, molecules, and subatomic particles. Since then, it has paved the way for practical applications such as precision measurement, laser technology, medical imaging and, probably the most far-reaching, semiconductor electronic devices and computer chips.
However, numerous aspects of the quantum world remained a mystery for a long time to scientists and engineers. Experimentally, the tiny scale of microscopic particles poses extraordinary challenges for studying the subtle laws of quantum mechanics in laboratory settings.
The promises of quantum machines
Since the late 20th century, researchers around the world have sought to isolate, control, and precisely measure individual physical objects, such as photons and atomic ions, that exhibit quantum behaviors under very specific experimental conditions.
These efforts gave rise to the emerging field of quantum engineering, which aims to harness the peculiarities of quantum physics to drive breakthrough technological innovations.
One of the most promising directions is quantum information processing, which aims to design machines capable of encoding, processing, transmitting and detecting information in “strange” quantum ways. For example: an object can be in a superposition of different states simultaneously, and distant objects can manifest quantum entanglement, that is, remote correlations that escape any classical interpretation.
Compared to conventional electronics, quantum information machines could present significant advantages in computing, simulation, cryptography, and sensing.
The creation of these machines requires that experimenters have access to reliable physical components that can be assembled and controlled on a human scale, but that fully obey quantum mechanics. As contradictory as it may seem, is it possible to transfer microscopic physical laws to macroscopic reality?
Quantum mechanics in an electrical circuit
In 1985, the three Nobel laureates, then members of the same research group at the University of California, Berkeley, answered this question in the affirmative. They studied superconducting electrical circuits.
Superconductivity is a special state of matter that allows electrical current to be conducted without resistance, due to the quantum interactions of electrons at low temperatures. For the first time, the trio observed distinctive quantum behaviors of a macroscopic physical variable.
Continue reading: The Nobel Prize in Physics recognizes the findings on quantum phenomena
In a superconductor, two electrons join together to form a Cooper pair, which condense into a macroscopic state shared by all its microscopic constituents. Trillions of electrons behave as a single entity, similar to everyday objects like pendulums or billiard balls.
To observe the quantum motion of this macroscopic phase variable, the scientists made a device called a Josephson junction, consisting of two pieces of superconductor separated by an insulating layer thinner than a tenth of a human hair.
At extremely low temperatures (below -273°C), the phase difference across the Josephson junction showed a unique quantum phenomenon known as tunneling, where an object can pass through a barrier without scaling its top.
The team also exposed the junction to microwave electromagnetic radiation and measured the circuit’s energy levels in discrete or quantized values, typically present only in microscopic atoms and molecules. Therefore, the device can be considered an “artificial atom”, that is, an electrical circuit of macroscopic size with quantum properties and adjustable design.
Implications and perspectives
The works of Clarke, Devoret and Martinis have had a profound impact. At a fundamental level, they demonstrated that specific quantum phenomena, previously restricted to the microscopic world, can manifest at larger physical scales.
The invention of superconducting artificial atoms has opened new avenues for building useful quantum machines using advanced engineering techniques.
Building on these discoveries, researchers have made significant progress in prototype quantum computers using superconducting circuits. The basic unit of these processors is the superconducting quantum bit, or “qubit,” which can be precisely prepared, manipulated, and measured. Its improvement and integration constitute one of the most advanced challenges of quantum information technology.
The 2025 Nobel Prize in Physics recognizes original research at the intersection of basic and applied sciences, where laureates demonstrated profound hypotheses of quantum mechanics through rigorous experimentation.
From these artificial atoms came bold efforts and rapid progress in building practical quantum information machines. The combination of theoretical research and engineering advances has defined this interdisciplinary field since its inception.
This award is a tribute to the inventors of superconducting quantum circuits, whose inquisitive minds and innovative vision embody the true scientific spirit and will continue to inspire future generations.
*Zhixin Wang is Postdoctoral Researcher in Physics, University of California, Santa Barbara
This article was originally published in The Conversation
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