In 2019, a research team at Google made a big breakthrough: their quantum computer managed to surpass the world's best supercomputers in solving a computational task (read more in Big breakthrough for quantum computers).
The chief scientist behind Google's quantum computer, world-famous Professor John Martinis, left Google the following year and returned to his university, University of California, Santa Barbara. However, he spent last month in Gothenburg as a guest researcher in Chalmers’ quantum computing team where Per Delsing and Jonas Bylander lead the engineering of a Swedish quantum computer. The focus has mainly been on the basic building blocks of the quantum computer – the qubits.
Broke new ground
Although Martinis and his former colleagues at Google broke new ground with their 53-qubit quantum computer, he admits that it did not work quite as well as they wanted. But it was difficult to find out why in the complex system that made up the quantum computer.
“Today people tend to focus on how many qubits you have. In my opinion, one needs to go back and improve the qubits before scaling up. I’ve been thinking quite deeply on how to make superconducting qubits better, and I wanted to come here because the Chalmers team is doing great work on this,” says John Martinis.
He does not have his own research group at the moment, but still many ideas about experiments that could be done to better understand the factors that affect the performance of the qubits.
“Many of the experiments I wanted to do last year, they already did here. From their data I’ve been able to better understand what’s going on with the materials in the qubits. And I have shared my ideas on how to analyze the data and about further experiments to do.”
"Many valuable suggestions"
Per Delsing describes John Martinis' visit as a shot in the arm:
“The entire group looks up to him, like a hero. The fact that we all got to spend time with him and his deep interest in what everyone is doing has been like a huge shot. John is extremely skilled and experienced and has given us many valuable suggestions on how to continue our work.”
The plan now is to stay in touch, to share results, thoughts and ideas.
“I think that really good things will come out of this,” says John Martinis.
Text: Ingela Roos
Photo: Kamanasish Debnath