Oxford physicists have used a hybrid quantum computer to block particle tunneling with magnetic flux. Notably, the particle never directly contacted the magnetic field. The team published its findings in Nature Physics.
The experiment simulates the Aharonov-Bohm effect, which Yakir Aharonov and David Bohm first predicted in 1959. This effect shows that a magnetic field can influence a charged particle even without physical contact. However, simulating this interaction with dynamic quantum fields has remained extremely difficult until now.
Dr. Sebastian Saner, a postdoctoral researcher at the University of Oxford, led the study alongside researchers from the Instituto de Fisica Teorica in Madrid. The team began developing the experiment in 2022. They built a hybrid system using trapped ions, where qubits encoded in the ions’ electronic states represent gauge fields. Meanwhile, quantum oscillators from ion vibrations represent matter particles.
The setup forms a loop: two oscillators sit at two points, and two qubits connect them. As a result, preparing the qubits in an entangled state effectively threads magnetic flux through the loop. Without this flux, the particle tunnels freely between the two locations. With flux present, the two possible paths interfere destructively. Consequently, the tunneling cancels out entirely, and the particle stays in its starting position.
“For us, the exciting step was to encode the magnetic flux in a gauge field that was itself dynamical,” Saner explained. He added that the matter and gauge field become part of the same quantum dynamics, rather than matter evolving in a fixed background.
Furthermore, a parallel University of Maryland team led by Professor Norbert Linke used a similar hybrid system to simulate the Yukawa potential. Both groups coordinated their submissions to Nature Physics.
The approach targets lattice gauge theories, which conventional computers struggle to model accurately. In addition, the researchers suggest this technique could eventually help explore physics beyond the Standard Model. Still, current quantum computers remain limited in scale and complexity for such simulations.