Beni Yoshida: A quantum explorer moved by music

Beni Yoshida has spent his career navigating the quantum realm, decoding the universe’s fundamental rules alongside brilliant colleagues and mentors. But it is a little girl, now nine years old, who is perpetually teaching him about art and beauty. 

“I have been very busy raising two kids,” Yoshida says, a Perimeter Institute faculty member specializing in quantum information theory. “My nine-year-old daughter is studying classical piano very seriously, and she’s a very good pianist. Because of that, we traveled a lot to other countries for competitions.”

Growing up in Osaka, Japan, Yoshida was drawn to mathematics. Something about the abstract elegance of equations, and the secrets of nature they revealed, captivated him. That passion led him to the University of Tokyo, then to MIT, where he studied quantum information theory under Peter Shor, the mathematician whose eponymous algorithm kick-started quantum computing research in the 1990s. 

“One important application of quantum information theory is quantum computers, where one might be able to potentially do super-fast computations which classical computers cannot do,” explains Yoshida.

While many researchers focus on building super-powerful computers, Yoshida’s curiosity extends further — to black holes, the nature of spacetime, and the fundamental structure of the quantum universe itself. His work bridges quantum information, condensed matter physics, and quantum gravity. 

Yoshida’s research in quantum information “scrambling” (the process by which information disperses and becomes nearly irretrievable) supports the idea that black holes do not destroy information but intricately encode it in recoverable ways. In a groundbreaking paper, "Quantum Information Scrambling on a Superconducting Qutrit Processor," Yoshida and collaborators demonstrated scrambling in higher-dimensional quantum systems, which could provide deeper insights into the fundamental speed limits for the spread of quantum information. 

The multidisciplinary nature of this research is what drew Yoshida to Perimeter back in 2017.

“I like the environment where there is academic freedom, and also there is cross-field collaboration, where I can work on problems in condensed matter theory and also quantum gravity as well.”

One of his key approaches is building what he calls “toy models” – simplified versions of complex quantum systems that capture their essential properties.

“I feel the most excited when I successfully found a toy model that explains key properties,” he says. 

“All the mysteries and puzzles in theoretical physics – they’re mysterious and puzzling because many conflicting ideas come in, and we don’t know how the phenomena are working. Sometimes, by extracting key properties of the physical system, you can construct a very simple but solvable toy model which captures key phenomena. If I can do that, then I can make a very sharp and precise statement, and I can explain the phenomena.”

Despite the mathematical rigour of his work – or maybe because of it? – Yoshida has found himself drawn into an entirely different world, where truth is expressed more emotionally than analytically; his daughter’s prodigious talent for classical piano has opened him to something unexpected.

His household is full of curiosity – his four-year-old son, he says, “is obsessed with science and math-type stuff,” while his wife, also from MIT, dabbles in piano. Yet his daughter’s artistic gifts are “the only singular existence in our family,” he says. 

“When I was young, I was not very interested (in music), but now I’ve started really appreciating it, and it’s a whole new world. I’m very happy that my daughter is broadening my interest to another world. I really thank my daughter for this.”