Oxford physicists stop a quantum particle using flux it never touches

[DigitalNomad62]

University of Oxford physicists have simulated the Aharonov-Bohm effect on a hybrid trapped ion quantum computer, and Interesting Engineering has a good write up. The effect, predicted by Yakir Aharonov and David Bohm in 1959, is one of the strangest in quantum mechanics. A magnetic field that a particle never passes through can still change how that particle behaves. In this experiment, the field stopped the particle from tunnelling between two locations

The team built a simulation of a lattice gauge theory, a framework used to describe how matter and force fields interact. Qubits stored in the ions' electronic states stood in for the field. The ions' vibrations stood in for matter. Two matter oscillators were linked through two field qubits to form a loop, and entangling those two qubits represented magnetic flux passing through the middle

With no flux, the particle tunnelled freely between the two sites. With flux, the two possible paths cancelled each other out, and the system kept returning to where it started. That is exactly the interference effect Aharonov and Bohm described, now seen in a programmable quantum simulator

There is a nice twist in how it came about. The researchers say encoding the flux in a dynamical field began as a workaround, because the hardware could not apply a fixed background flux. But it turned into a feature, because it let them study a field that changes along with the matter. Sebastian Saner of Oxford led the work, which has been in development since 2022 and is published in Nature Physics

Simulations like this are one of the most promising near term uses of quantum computers. Lattice gauge theories are extremely hard to study on classical machines, especially when things change over time. The article also mentions a related University of Maryland study led by Norbert Linke that simulated the Yukawa potential, so this area is clearly gathering pace

Do you think quantum simulation of gauge theories will produce new physics before quantum computers crack chemistry problems? And how much do you enjoy seeing classic thought experiments tested like this?

Scientists stop quantum particle using magnetic field it never crossedinterestingengineering.com

[Riff]

Classic thought experiments becoming real experiments never gets old. Students learn about Aharonov-Bohm as theory, and now there is a programmable version. It would make a fantastic teaching example. Physics teachers will be grateful for examples like this

[Calm Paige]

Turning a hardware limitation into a better experiment is great science. The team could have waited for equipment that applied a fixed flux. Instead they found a richer way to do it. That kind of creativity is what moves fields forward

Necessity is the mother of invention in labs. Some of the best results come from workarounds

[Tracey]

Aharonov-Bohm is one of my favourite effects in physics. The idea that a potential matters even where the field is zero still feels strange decades later

Seeing it built from trapped ions is a lovely demonstration. It still feels like magic when you first learn it