Imagine a particle that can be stopped without touching it or applying a force directly. Even stranger, the effect occurs because of a magnetic influence that the particle never physically passes through. This may sound impossible, but scientists have recreated this unusual phenomenon using a hybrid quantum computer.
Researchers at the University of Oxford have demonstrated how a simulated magnetic flux can stop a particle from moving between locations through a process called quantum interference. The experiment recreates a famous quantum phenomenon known as the Aharonov–Bohm effect, which challenges our everyday understanding of how magnetic fields influence matter.
The findings, published in Nature Physics in 2026, provide a new way to study the relationship between matter and quantum fields. They also demonstrate how quantum computers could help scientists investigate some of the most complicated problems in fundamental physics.
A Strange Quantum Effect First Predicted in 1959
In everyday life, objects respond to forces through familiar physical interactions. A charged particle, for example, can be influenced by magnetic fields. However, quantum mechanics reveals that particles can respond to their surroundings in ways that are very different from what classical physics predicts.
In 1959, physicists Yakir Aharonov and David Bohm proposed a surprising idea: a charged particle could experience a measurable quantum effect even when its path never passes through the region containing a magnetic field.
Instead of being pushed or pulled by the magnetic field along its path, the particle's quantum state changes in a way that affects how its possible paths interact.
This phenomenon became known as the Aharonov–Bohm effect.
To understand it, scientists must consider that quantum particles behave like waves in certain situations. These waves have a property called phase, which influences how they combine with other waves.
When two possible paths have compatible phases, their contributions can reinforce one another. When their phases oppose each other, they can cancel out.
Although quantum phase is not directly visible, its effects can be measured through interference.
The Aharonov–Bohm effect demonstrates that magnetic flux can change this phase relationship even when a particle travels entirely outside the region containing the magnetic field. Experiments with real electrons have previously confirmed this unusual behavior.
Now, researchers are investigating how the same principle operates in more complex systems where matter and quantum fields interact dynamically.
How Oxford Scientists Built Their Quantum Experiment
The Oxford research team began developing its approach in 2022. The project involved lead author Dr. Sebastian Saner, Dr. Oana Băzăvan and their colleagues, working with Dr. Alejandro Bermúdez of the Instituto de Física Teórica in Madrid.
Their goal was to simulate a theoretical system known as a lattice gauge theory.
These theories help physicists describe how matter interacts with fields associated with fundamental forces. They represent space as a grid, with matter occupying specific locations and fields connecting those locations.
Such models are important for understanding particle physics and the interactions underlying the universe. However, calculating their behavior becomes extremely difficult as the number of interacting components increases.
Conventional computers can struggle to reproduce the full quantum behavior of these systems.
Quantum computers offer a different approach. Rather than calculating every detail using ordinary computing methods, scientists can build a controllable quantum system that follows similar physical rules. They can then observe how that system behaves.
For their experiment, the Oxford researchers combined two quantum components.
The first consisted of qubits encoded in the internal states of trapped ions. Qubits are the basic units of quantum information, and the researchers used them to represent the fields in their theoretical model.
The second component consisted of quantum oscillators, which represented matter. These oscillators were associated with the vibrational motion of the same trapped ions.
By combining these components, the researchers created a small quantum loop. Two oscillators represented matter at two different locations, while two qubits represented the fields connecting them.
Although this was a simplified model, it allowed the team to investigate how magnetic flux could influence the movement of matter through quantum interference.
Quantum Entanglement Helped Represent Magnetic Flux
The next challenge was introducing magnetic flux into the simulated system.
The researchers initially considered representing the flux as a fixed background condition. However, their quantum hardware lacked the capabilities needed to implement the required interaction in that form.
They instead encoded the flux into an entangled state of the two qubits.
Quantum entanglement occurs when quantum systems become connected so that their states cannot be fully described independently of one another.
In the Oxford experiment, the entangled qubits represented magnetic flux passing through the center of the simulated loop.
This approach offered an important advantage. The magnetic flux was no longer simply an unchanging external influence. It became part of the quantum system itself and could participate in the system's evolving dynamics.
Dr. Saner explained that this allowed the researchers to move beyond studying matter in a fixed background and investigate a situation in which matter and the gauge field evolved together.
This distinction is important because many fundamental physical interactions involve fields that change and respond to the systems around them.
How Magnetic Flux Stopped the Particle
The most striking result appeared when the researchers examined how matter moved between the two locations in their simulated loop.
The movement occurred through a quantum process called tunneling. Quantum tunneling allows a particle to transition between states even when classical physics would not permit the same process under the same conditions.
Without magnetic flux, the simulated particle could tunnel between locations through the available paths around the loop.
However, when the researchers introduced the simulated magnetic flux, the behavior changed dramatically.
The particle had two possible routes around the loop. The magnetic flux changed the relative quantum phases associated with those routes.
As a result, the two possible paths interfered destructively. Their contributions canceled each other, suppressing the tunneling process.
The simulated particle effectively stopped moving between the two locations.
This result is a striking example of how quantum interference can control the behavior of matter. The particle did not need to encounter a conventional magnetic force along its path for the magnetic flux to affect its movement.
Instead, the effect emerged from the relationship between the phases of its possible quantum paths.
The experiment recreated the Aharonov–Bohm effect in a lattice gauge theory where the field itself was part of the evolving quantum system.
It is important to note that the researchers did not stop an ordinary particle in a laboratory by surrounding it with a real magnetic field. They demonstrated the effect using a controlled quantum simulation of a particle and its interactions.
Why This Discovery Matters
The experiment represents a step forward in the use of quantum computers to investigate fundamental physics.
Scientists increasingly want to understand systems involving many interacting particles and fields. These systems can be extraordinarily difficult to simulate accurately with conventional computers because quantum effects become more complicated as the number of components grows.
Quantum simulators provide an alternative by reproducing selected features of the physical systems scientists want to understand.
The Oxford team's approach demonstrates how different quantum components can be combined to represent matter and fields within a single system. It also shows how researchers can investigate situations in which those components influence one another dynamically.
The findings appeared alongside a related study by researchers at the University of Maryland, led by Professor Norbert Linke. That team used a hybrid quantum system to investigate quantum field theory dynamics, including the simulation of the Yukawa potential, which is relevant to interactions in particle and nuclear physics.
Although the experiments explored different questions, together they highlight the growing potential of hybrid quantum computing for studying fundamental interactions.
Future research may extend these techniques to more complex models, helping scientists investigate quantum field theories that are difficult to explore using conventional computational methods.
However, these systems remain experimental tools. They do not yet replace conventional computers or provide direct solutions to every outstanding question in physics.
A New Way to Explore the Quantum World
The Aharonov–Bohm effect has fascinated physicists for decades because it reveals that quantum particles can be influenced by magnetic flux even when they never travel through the region containing the magnetic field.
The Oxford experiment takes this idea into a new setting by reproducing the effect with a hybrid quantum computer in which matter and fields participate in the same quantum dynamics.
By showing how quantum interference can suppress a particle's movement, the researchers have demonstrated another way to control and investigate quantum behavior.
The result is not simply about making a particle stop. It is about understanding how the invisible relationships between quantum states can determine what matter does.
As quantum simulation technology develops, experiments like this could give scientists valuable new tools for exploring the fundamental rules that govern the universe.
References:
- S. Saner, O. Băzăvan, D. J. Webb, G. Araneda, C. J. Ballance, R. Srinivas, D. M. Lucas, A. Bermúdez. Aharonov–Bohm interference in a $${\\pmb{\\mathbb{Z}}}_{\\bf{2}}$$ lattice gauge theory on a hybrid qubit–oscillator quantum computer. Nature Physics, 2026; DOI: 10.1038/s41567-026-03400-6
- Anton T. Than, Saurabh V. Kadam, Vinay Vikramaditya, Nhung H. Nguyen, Xingxin Liu, Zohreh Davoudi, Alaina M. Green, Norbert M. Linke. Quantum field theory dynamics on a spin–phonon quantum computer. Nature Physics, 2026; DOI: 10.1038/s41567-026-03402-4
Comments
Post a Comment