The 2025 Nobel Prize in physics has been awarded to three physicists for their groundbreaking work in scaling quantum effects to new dimensions.
In the 1980s, John Clarke, Michel Devoret, and John Martinis made significant strides in demonstrating quantum tunneling and energy quantization within an electrical circuit. Their experiments showcased the interaction of billions of electrons within a chip small enough to hold in one hand, defying previous assumptions that quantum effects were limited to individual atoms.
“Our discovery laid much of the groundwork for quantum computing,” stated Clarke from the University of California, Berkeley during the Oct. 7 announcement by the Royal Swedish Academy of Sciences. He shares the prize of 11 million Swedish kronor (over $1.1 million) with Martinis from UC Santa Barbara and Devoret from Yale University and UC Santa Barbara.
Since their discovery, various tech companies and researchers globally have utilized similar circuits as quantum bits, or qubits, fundamental to quantum computing.
Quantum tunneling is a non-intuitive phenomenon where a quantum system traverses an apparently insurmountable barrier, akin to a ball rolling partway up a hill and unexpectedly appearing on the opposite side. The team illustrated this process using a device known as a Josephson junction, formed by a superconductor—an electricity-conducting material with zero resistance—sandwiched between an insulator.
In a pivotal 1985 paper published in Physical Review Letters, the researchers reported that at extremely low temperatures, the circuit was capable of tunneling between a no-voltage state and one with voltage. Additionally, in another paper that year, they demonstrated that the circuit absorbed energy in discrete amounts, a concept known as quantization.
“This is the cornerstone of why superconducting qubits are functional,” remarked physicist Andreas Wallraff from ETH Zurich, who is active in the field. “What is remarkable is that not only did they conduct this pivotal experiment, but they continually advanced the field in various significant ways.”
For instance, Martinis played a crucial role in demonstrating that a quantum computer could execute calculations beyond the reach of classical computers. In 2019, while leading Google’s quantum computing initiative, his team controversially claimed to have achieved this milestone. The pursuit of this benchmark has sparked ongoing debate.
The capabilities of quantum computers stem from the unique principles of quantum mechanics, which deviate from the norms governing everyday objects. This distinctive nature grants these computers the potential to accomplish tasks such as breaching standard encryption methods that secure online communications. The award coincides with a year-long celebration of quantum mechanics, marking its centenary.
