Quantum breakthrough without magnets: Lithuanian physicists have learned to "program" atoms with light
Researchers from the Faculty of Physics at Vilnius University have presented a theoretical model that fundamentally changes the approach to controlling quantum systems. Instead of the traditional use of bulky external magnetic fields, the new method proposes "programming" atoms using only light.
The essence of the development lies in a two-stage process. First, a laser beam sets atoms to a specific state — effectively writing a "program" into them. Then, this pre-prepared atomic medium begins to actively influence the complex laser beams passing through it, altering their shape and polarization.
Optical Vortices and Unlimited Encoding Possibilities
A key element of the model is optical vortices — laser beams with a spiral wavefront structure. At the center of such a vortex, the intensity drops to zero, forming a dark region. The size of this region is determined by the topological charge, which, as the authors note, can take any integer value — both positive and negative, without any restrictions.
In practice, this opens the way to using up to 10,000 different states. Instead of the familiar qubits, which operate with only two states (0 and 1), we can transition to qudits — multi-level units of quantum information. This exponentially increases the amount of data that can be encoded in a single quantum carrier.
Feedback: How Atoms "Redraw" Light
To control vector vortices, the scientists modeled the interaction of a laser beam with an atomic gas, where each atom has three energy levels. In this scheme, the prepared medium literally "inherits" the spatial pattern of light. In some regions, atoms begin to intensely absorb radiation; in others, they become almost transparent. A feedback effect emerges: the atomic response reshapes the beam itself.
As a result, instead of a simple ring structure, a complex petal pattern forms with several bright regions around the center. Simultaneously, the polarization structure of the radiation changes. Previously, achieving such control required powerful magnets and complex equipment. Now, everything is resolved at the optical level.
Practical Prospects and Expert Assessment
Theoretically, this development paves the way for creating faster quantum processors, highly secure communication networks, and ultra-precise optical sensors. Eliminating magnetic fields not only simplifies the design but also reduces noise levels, which is critically important for quantum computing.
My professional opinion: This work is an elegant example of how fundamental physics finds workarounds to solve engineering problems. If the model is successfully implemented in practice, we will get not just an evolutionary improvement, but a true paradigm shift in the field of quantum switching and sensing. The potential with thousands of qudit states is particularly impressive — this is a direct path to quantum supremacy in tasks where traditional qubits are powerless.