One Branch of Quantum Computing Owes Its Existence to This Year’s Nobel Laureates in Physics

This year’s Nobel Prize in Physics has been awarded to three scientists – British physicist John Clarke, French researcher Michel H. Devoret, and American physicist John M. Martinis – for their discovery of macroscopic quantum mechanical tunnelling and energy quantisation. The trio created a superconducting circuit in which they observed quantum mechanical phenomena, demonstrating that quantum effects are not limited to atoms – quantised energy levels can also manifest in larger-scale systems.

“Imagine a circuit you could hold with tweezers: whereas an atomic nucleus contains 10 to 100 electrons, this sort of system naturally involves many orders of magnitude more,” explained Péter Makk, Associate Professor and Head of the Department of Physics at BME, in response to a query from bme.hu. 

“The essence of the tunnelling effect is that under certain conditions, electrons can pass through an insulating layer between two metal plates. 

In the system studied by the new Nobel Laureates, superconducting metals were placed on either side of the insulator. This configuration creates what is known as a Josephson junction, across which electron pairs can tunnel without generating a voltage drop. Their experiment demonstrated that by irradiating the circuit with a precisely defined frequency, it is possible to induce excitations between quantised energy levels – and the appearance of voltage across the junction indicates that this has occurred,” Makk explained.

But why is this significant?

These experiments and circuits form the basis of modern quantum technology – specifically, one of the key directions in quantum computer development, the superconducting qubit architecture. Clarke and his colleagues have thus laid the foundations for a major branch of quantum computing. As Makk added, following this discovery, related research was also carried out at BME. “For example, we were the first in Hungary to study superconducting qubits in a BME laboratory, and our students have the opportunity to program quantum computers based on these principles in our courses,” he noted.

Devoret has previously collaborated with a Hungarian researcher as well: he co-authored a publication with Attila Geresdi, a BME graduate who earned his PhD at the University and now works for the Finnish-owned company IQM.

This year also marks the 100th anniversary of quantum theory. BME recently hosted a conference to celebrate the occasion, bringing together leading experts in quantum technology.

Rector's Office, Directorate of Communications