Nobel Prize in Physics 2025

John Clarke, Michel Devoret and John Martinis discovered quantum physics on a macroscopic scale, paving the way for quantum computing.

In 1985, experiments revealed the quantum behaviour of a macroscopic degree of freedom: the phase difference across a Josephson junction. The authors recount the history of this milestone for the development of superconducting quantum circuits.

John Clarke told Nature Materials about his work on superconducting quantum interference devices — SQUIDs — and his fascination with their applicability to many fields, from medicine to geophysics to quantum information and cosmology.

The demonstration of coherent control of a superconducting qubit in 1998 helped trigger the development of quantum computing platforms using solid-state devices and circuits. Yasunobu Nakamura recounts how this Cooper-pair-box experiment was devised.

Gabriele Rainò, Lukas Novotny and Martin Frimmer discuss the approach they are pursuing at ETH Zürich to provide students with an education in quantum engineering.

Granular aluminium — a superconductor with high kinetic inductance — has been used to create a superinductor for a fluxonium superconducting qubit.

The introduction of concepts from cavity quantum electrodynamics to superconducting circuits yielded circuit quantum electrodynamics, a platform eminently suitable to quantum information processing and for the exploration of novel regimes in quantum optics.

Hybrid quantum systems combine heterogeneous physical systems for the implementation of new functionalities at the quantum level. This article reviews recent research on the creation of hybrid quantum systems within the circuit quantum electrodynamics framework.

Semiconductor qubits are expected to have diverse future quantum applications. This Review discusses semiconductor qubit implementations from the perspective of an ecosystem of applications, such as quantum simulation, sensing, computation and communication.

Superconducting qubits hold great promise for quantum computing, and recently there have been dramatic improvements in both coherence times and the power of quantum processors. This Review explores how the path forward involves balancing circuit complexity and materials perfection, eliminating defects while designing qubits with engineered noise resilience.

The exceptional quality of hexagonal boron nitride crystals that can be cleaved into few layers provides ultrathin dielectrics, thereby opening a route to ultrasmall capacitors with large capacitances. With such capacitors, the superconducting transmon qubit is scaled down by orders of magnitude.

Superconducting qubits could be used to build a fault-tolerant quantum computer. But such a device will require millions of components, and various fundamental challenges remain to be addressed. Success will depend on sustained collaboration between industry and academia.

Quantum solutions are typically evaluated in terms of performance, efficiency, speedup or the number of qubits — but not energy consumption. Yet quantum computing comes at a high energy cost. To make sure quantum computing is developed energy-efficiently, it is essential to optimize the design of the circuit, and pay attention to aspects such as the circuit layout and how the execution is done on the quantum computer.

Defects in Josephson junctions are considered a nuisance when it comes to using superconducting circuits as building blocks for a quantum-information processor. But if the interaction between the circuit and defects is accurately controlled—as has been demonstrated now—the imperfections might be useful, serving as memory elements.

The long-predicted suppression of quasiparticle dissipation in a Josephson junction when the phase difference across the junction is π is inferred from a sharp maximum in the energy relaxation time of a superconducting artificial atom.

Superconducting circuits are one possible way of realizing qubits, but the time for which they can maintain their quantum state is limited by single-electron-like excitations. Wang et al. now demonstrate a technique for controlling these so-called quasiparticles and improving qubit lifetime.

Quantum errors present a fundamental challenge for quantum information storage and manipulation. Zhong et al.implement a protocol based on quantum measurement uncollapsing to detect and reject quantum errors in a superconducting qubit, thereby increasing the storage time of a quantum state by a factor of three.

Scalable quantum information processing requires controllable high-coherence qubits. Here, the authors present superconducting flux qubits with broad frequency tunability, strong anharmonicity and high reproducibility, identifying photon shot noise as the main source of dephasing for further improvements.

Experiment overturns Bohr’s view of quantum jumps, demonstrating that they possess a degree of predictability and when completed are continuous, coherent and even deterministic.

A qubit generated and stabilized in a superconducting microwave resonator by encoding it into Schrödinger cat states produced by Kerr nonlinearity and single-mode squeezing shows intrinsic robustness to phase-flip errors.

A quasiparticle in Andreev levels was coupled to a superconducting microwave resonator and its spin was monitored in real time. This has potential applications in the readout of superconducting spin qubits and measurements of Majorana fermions.

It is hoped that quantum computers may be faster than classical ones at solving optimization problems. Here the authors implement a quantum optimization algorithm over 23 qubits but find more limited performance when an optimization problem structure does not match the underlying hardware.

A noise-resilient protocol implemented in a cavity resonator coupled to a qubit demonstrates that large nonlinear couplings are not a necessary requirement for the fast universal control and state preparation of engineered quantum systems.

Cosmic rays flying through superconducting quantum devices create bursts of excitations that destroy qubit coherence. Rapid, spatially resolved measurements of qubit error rates make it possible to observe the evolution of the bursts across a chip.

Quantum supremacy is demonstrated using a programmable superconducting processor known as Sycamore, taking approximately 200 seconds to sample one instance of a quantum circuit a million times, which would take a state-of-the-art supercomputer around ten thousand years to compute.

A study demonstrates the extension of a lifetime of a quantum memory using active quantum error correction and reinforcement learning.

Bell inequalities are a quantitative measure that can distinguish classically determined correlations from stronger quantum correlations, and their measurement provides strong experimental evidence that quantum mechanics provides a complete description. The violation of a Bell inequality is now demonstrated in a solid-state system; the experiment provides further strong evidence that a macroscopic electrical circuit is really a quantum system.

Quantum entanglement is one of the key resources required for quantum computation. In superconducting devices, two-qubit entangled states have been used to implement simple quantum algorithms, but three-qubit states, which can be entangled in two fundamentally different ways, have not been demonstrated. Here, however, three superconducting phase qubits have been used to create and measure these two entangled three-qubit states.

Recent progress in solid-state quantum information processing has stimulated the search for amplifiers and frequency converters with quantum-limited performance in the microwave range. Here, a phase-preserving, superconducting parametric amplifier with ultra-low-noise properties has been experimentally realized.

Quantum mechanics provides an accurate description of a wide variety of physical systems but it is very challenging to prove that it also applies to macroscopic (classical) mechanical systems. This is because it has been impossible to cool a mechanical mode to its quantum ground state, in which all classical noise is eliminated. Recently, various mechanical devices have been cooled to a near-ground state, but this paper demonstrates the milestone result of a piezoelectric resonator with a mechanical mode cooled to its quantum ground state.

Quantum simulators offer a test bed to emulate physical phenomena that are difficult to reproduce numerically. Using a multi-element superconducting quantum circuit, Chen et al.emulate weak localization for a mesoscopic system using a control sequence that lets them continuously tune the level of disorder.

A universal set of logic gates in a superconducting quantum circuit is shown to have gate fidelities at the threshold for fault-tolerant quantum computing by the surface code approach, in which the quantum bits are distributed in an array of planar topology and have only nearest-neighbour couplings.

A quantum error correction scheme is demonstrated in a system of superconducting qubits, and repeated quantum non-demolition measurements are used to track errors and reduce the failure rate; increasing the system size from five to nine qubits improves the failure rate further.

A digitized approach to adiabatic quantum computing, combining the generality of the adiabatic algorithm with the universality of the digital method, is implemented using a superconducting circuit to find the ground states of arbitrary Hamiltonians.

A quantum-error-correction system is demonstrated in which natural errors due to energy loss are suppressed by encoding a logical state as a superposition of Schrödinger-cat states, which results in the system reaching the ‘break-even’ point, at which the lifetime of a qubit exceeds the lifetime of the constituents of the system.

As a benchmark for the development of a future quantum computer, sampling from random quantum circuits is suggested as a task that will lead to quantum supremacy—a calculation that cannot be carried out classically.

Sending quantum states as shaped microwave photonic wavepackets realizes on-demand, high-fidelity quantum state transfer and entanglement between two superconducting cavity quantum memories.

Sparsification techniques can be used to create Ising machines prototyped on field-programmable gate arrays that can quickly and efficiently solve combinatorial optimization problems.

Biased noise qubits, which can selectively suppress certain types of noise, are advantageous for quantum error correction of bosonic codes. Here the authors make an important step in this direction by demonstrating quantum control of a harmonic oscillator with a biased noise qubit.

Local temperature measurements are important in the study of quantum thermodynamics at the nanoscale. The authors report a sensor based on cyclic electron tunnelling between a quantum dot and single-electron reservoir which can be used to provide local and precise temperature measurements in nanoelectronic devices.

A fluxonium qubit is constructed out of granular aluminium, revealing its potential for superconducting quantum technologies.

Heat transport control in superconducting circuits has received increasing attention in microwave engineering for circuit quantum electrodynamics, particularly in light of quantum computing. The authors realise of a quantum heat rectifier, a thermal equivalent to the electronic diode, experimentally realising a spin-boson rectifier proposed theoretically.

Many features of a superconductor are encoded in the Josephson effect and understanding changes at the local level can help explain related phenomena. Here, the authors use scanning tunnelling microscopy to study local changes in the Josephson effect and how they relate to the transport channel configuration.

Josephson junctions have applications in quantum circuits but producing and controlling the coupling between junctions is challenging. The authors characterize the electronic transport properties of two adjacent Josephson junctions, demonstrating short-range coherent coupling indicative of a nonlocal Josephson effect.

Superconducting hybrid systems are becoming an increasingly important platform to conduct investigations in the field of quantum information processing. Here, the authors report a highly cooperative coupling between the nuclear spin of an Yb(III) molecular complex with a superconducting microwave resonator achieving a large hyperfine-mediated coupling between a resonator mode and the nuclear spin that could be used for the realization and readout of qudits.

Parallel-plate capacitors of the two-dimensional materials hBN and NbSe₂ are integrated with aluminium Josephson junctions to realize transmon qubits with coherence times reaching 25 μs.

The authors fabricate a fluxonium circuit using a granular aluminium nanoconstriction to replace the conventional superconductor–insulator–superconductor tunnel junction. Their characterization suggests that this approach will be a useful element in the superconducting qubit toolkit.

A loophole-free violation of Bell’s inequality with superconducting circuits shows that non-locality is a viable new resource in quantum information technology realized with superconducting circuits, promising many potential applications.

Superconducting currents around a loop containing a weak link can be quantized and only change during discrete events called phase slips. Now, the heat generated by a single phase slip and the subsequent relaxation have been experimentally observed.

Nonreciprocal transport is a fundamental property of semiconducting-based electronics and the possibility of extending this to superconducting circuits without external magnetic field is a promising but challenging field of research. Here, the authors report a field-free superconducting diode effect for 2H-NbSe₂ Josephson junctions with the results suggesting the existence of spontaneous time-reversal symmetry breaking.

The superconducting diode effect has the potential to advance the design of non-dissipative circuit components yet there are many practical aspects to overcome before reaching the application stage. Here, the authors investigate the non-reciprocal current-voltage relationship in gate-controlled metallic nanowires, demonstrating the realisation of the superconducting diode effect without the need to break time-reversal symmetry using an applied magnetic field.