The Nobel Prize in Physics in the “quantum year” 2025 honors the achievements of John Clarke, Michel H. Devoret, and John M. Martinis in the field of macroscopic quantum phenomena and celebrates the centenary of quantum mechanics. The realization of quantized electrical circuits has enabled, among other things, superconducting qubits, which are a key technology for quantum computers.
Typically, quantum effects such as tunneling through classically insurmountable barriers can only be observed on extremely small scales. This makes states such as superpositions possible, in which microscopic particles can exist on both sides of a barrier. In the 1970s, the award-winning researchers at the University of California, Berkeley, succeeded in demonstrating this tunneling effect on macroscopic scales and creating superpositions based on tunneling through Josephson junctions. These are extremely thin insulators in superconducting electrical circuits.
This discovery laid the foundation for not only measuring quantum systems, but also for designing, manufacturing, and controlling them in laboratories. Since the early 2000s, superconducting qubits based on Josephson junctions have been developed that enable two stable quantum states. Although they were initially highly susceptible to interference, it has been possible to significantly extend the decoherence times and improve control and readout.
A milestone was the recent demonstration of error-corrected quantum processors. This impressively showed that the quality of quantum computers improves by scaling the system. With sufficiently large systems, relevant chemical simulations, materials research, or optimization tasks could be performed in the future. Munich Quantum Valley is also actively driving this research forward in Germany. Here, universities and research institutes such as the Technical University of Munich, the Walther Meißner Institute of the Bavarian Academy of Sciences and Humanities, and the Fraunhofer Institute EMFT are pooling their expertise with industry partners to further develop superconducting qubits – from materials research to system integration.