Physicists have found a way to "program" atoms with light without magnetic fields — a breakthrough for quantum computing
A group of researchers from the Faculty of Physics at Vilnius University has presented a theoretical model that allows for the preliminary "programming" of atoms using light, completely eliminating the need for external magnetic fields. This is a fundamentally new approach to controlling quantum systems.
The idea is as follows: a light beam first sets the atoms to a specific state, and then this pre-prepared atomic medium begins to actively change the shape and polarization of complex laser beams. The key element of the model is optical vortices, i.e., beams with a spiral wavefront structure. At their center, the intensity drops to zero, forming a dark region. The size of this region is determined by the topological charge, which, as the authors emphasize, has no limitations and can take any integer value — both positive and negative.
In practice, this means that up to 10,000 different states can be obtained. Instead of the familiar qubits, which operate with only two states, we are talking about qudits — multi-level units of quantum information. This opens up enormous possibilities for data encoding.
To control vector vortices, the scientists modeled the interaction of the beam with an atomic gas where the atoms have three energy levels. In such an environment, the prepared gas "remembers" the spatial pattern of the light: in some areas, the atoms begin to actively absorb radiation, while in others, they become almost transparent. A feedback effect then occurs: the atomic response restructures the beam itself, turning a simple ring structure into a complex petal pattern with several bright regions around the center. At the same time, the polarization structure of the beam also undergoes changes.
Previously, such control required powerful external magnetic fields and bulky equipment. The new model eliminates this dependency, which radically simplifies potential experimental setups.
Theoretically, this development paves the way for creating faster quantum processors, highly secure quantum communication networks, and ultra-precise optical sensors.
Analytical commentary from Cryptalist: This approach looks particularly promising against the backdrop of recent advances in quantum hardware. For example, just a few days ago, Sandia National Laboratories and Quantinuum published a peer-reviewed paper on the 98-qubit Helios quantum computer. However, scaling qubits is only half the battle. The ability to control qudits without magnetic fields could be the missing link that transforms quantum computing from a laboratory curiosity into engineering reality. We are following the developments.