Quantum breakthrough without magnets: how light teaches atoms new states
At the Faculty of Physics of Vilnius University, a theoretical model has been proposed that allows "programming" atoms exclusively with light, completely eliminating external magnetic fields. This fundamentally changes the approach to controlling quantum systems.
Light "Code" for the Atomic Medium
The concept is based on a two-stage process. First, a laser beam sets the initial state of the atoms — a kind of "program." Then, this pre-prepared atomic medium begins to actively influence the light passing through it, altering its shape and polarization. The key elements are optical vortices — beams with a spiral wavefront. At the center of such a vortex, the intensity drops to zero, and the size of this dark zone is determined by the topological charge, which, as the researchers note, is not limited and can take any integer value — both positive and negative.
From Qubits to Qudits: 10,000 States
The practical value of the model is revealed in the ability to encode information not in traditional qubits (two states), but in qudits — multi-level quantum units. Theoretically, this allows for up to 10,000 different states, dramatically increasing the information capacity and stability of quantum computing.
Self-Restructuring Mechanism
To control vector vortices, the scientists simulated the interaction of a beam with an atomic gas having three energy levels. The prepared medium "inherits" the spatial pattern of the light: in some areas, atoms actively absorb radiation, while in others they become almost transparent. A feedback loop emerges — the atomic response restructures the beam itself, transforming a simple ring structure into a complex petal pattern with several bright regions around the center. Simultaneously, the polarization structure also changes. Previously, such control required powerful magnetic fields and bulky equipment.
Theoretically, this development paves the way for creating faster quantum processors, highly secure communication networks, and ultra-precise optical sensors.
Expert Comment: Eliminating magnetic fields is not just a simplification of the scheme but the removal of a fundamental limitation on scaling. If the model is confirmed experimentally, we will obtain much more compact and energy-efficient quantum systems, where state control occurs at the level of light itself. This could become the bridge between laboratory prototypes and real quantum computers.