2025 Nobel Prize in Physics: where it all began

It’s not quite ‘Beam me up Scotty!’ of Star Trek lore, nor Harry Potter’s magical ‘Apparition’ transportation.

But the 2025 Nobel Laureates in Physics have proved that particles can pass through a solid wall, leaving the wall untouched.

‘It’s like you’re kicking a football against a wall, and one time it makes its way through, leaving the wall untouched,’ says Trinity’s Professor of Theoretical Physics David Tong.

It’s called quantum tunnelling – one of the more bizarre aspects of quantum mechanics, a theory developed 100 years ago, which asserted the inherently unknowable nature of natural phenomena.

In 1925 when Werner Heisenberg, Paul Dirac and Erwin Schrödinger theorised this new way of describing the world, and in 1985 when today’s Nobel Laureates metaphorically kicked a football through a solid wall, no-one predicted the consequences of quantum mechanics for society.

Today all advanced technology, including computers, mobile phones and fibre optic cables, rely on quantum mechanical effects among atoms and electrons.

Cambridge alumnus Professor John Clarke was ‘completely stunned’ to hear that he and his colleagues, Professors Michel Devoret and John Martinis, had won the 2025 Nobel Prize in Physics. When conducting their ground-breaking experiments at Berkeley in the 1980s, Clarke said, ‘it had not occurred to us that this discovery would have such a significant impact.’

As the 2025 Nobel Committee for Physics makes clear, their achievement was inextricably linked to the work of Trinity Fellow Professor Brian Josephson, who in the 1960s predicted quantum tunnelling in superconductors.

For his theoretical predictions of an electrical current flowing between two pieces of superconducting material, separated by a thin layer of insulation, Professor Josephson received the 1973 Nobel Prize.

Professor Clarke paid tribute to Josephson’s ‘enormous impact on me.’

He and I were colleagues as graduate students together all those years ago in Cambridge. I recognize that he was much more brilliant than I was.

‘Brian Josephson continues to challenge people and make them think to this day,’ Professor Clarke said, also citing the influence of Nobel Laureate Professor Sir Anthony Leggett and the importance of collegiality among scientists.

The experiments that validated the Josephson Effect involved electron pairs (known as Cooper pairs) tunnelling through ‘walls’.

Professor Tong explains: ‘The new experiments ramp this up, building devices in which a macroscopically large current tunnels through. It’s not quite the football scale, but it’s now thousands of electrons. So in some sense, it’s just a vast improvement on Brian’s original idea. But it’s a key step for several reasons.’

First, it shows that quantum mechanics continues to hold for macroscopic objects. The predictions of quantum mechanics are so weird that it’s nice to have explicit demonstrations that it keeps on working as things get bigger.

Second, this is what you need for technology. There are already uses in building sensing equipment. But the real pay-off comes with quantum computers, a new kind of device that, in principle, can outstrip any current computer in terms of speed. These quantum computers already exist – but they’re at early stages.

‘You not getting your iPhone upgraded to a q-iPhone anytime soon. But this Nobel Prize will surely be seen as an early nod to that research programme,’ said Professor Tong.

Illustration: Johan Jarnestad/The Royal Swedish Academy of Sciences.