Programming light: physicists have found a way to control atoms without magnetic fields
A group of researchers from the Faculty of Physics at Vilnius University has presented a theoretical model that fundamentally changes the approach to controlling quantum systems. Instead of traditional external magnetic fields, the authors propose using light to "program" atoms — and then making this prepared medium change the shape and polarization of complex laser beams.
The key element of the model is optical vortices. These are beams with a spiral wavefront structure, where the intensity drops to zero at the center. The size of this dark zone is determined by the topological charge, which, as the scientists note, is not limited and can take any positive or negative integer values. In practice, this means the ability to generate up to 10,000 different states — and encode information in qudits, multidimensional quantum units that are much more capacious than conventional qubits.
To control vector vortices, the researchers analyzed the interaction of a laser beam with an atomic gas, where the atoms have three energy levels. In the model, the prepared medium literally "inherits" the spatial pattern of light: in some areas, atoms strongly absorb radiation, while in others they become almost transparent. Then feedback occurs — the atomic response restructures the beam itself. Instead of a simple ring structure, a petal-like pattern with several bright regions around the center appears, and the polarization structure transforms. Previously, such control required powerful external magnetic fields and complex equipment.
Theoretically, this development paves the way for faster quantum processors, highly secure quantum communication networks, and ultra-precise optical sensors.
My expert commentary: This approach is an excellent illustration of how fundamental science is gradually removing technological barriers in quantum computing. Abandoning magnetic fields simplifies hardware implementation and reduces noise, which is critically important for scaling. If the model can be realized in an experiment, we will gain not just a new tool, but a paradigm shift in the control of quantum states.