Non-magnetic programming of atoms: a new perspective on quantum computing
Physicists from the Department of Theoretical Physics at Vilnius University have introduced an innovative model that allows "programming" atoms using light, completely eliminating the need for external magnetic fields. This marks a significant step forward in the fields of quantum communications and optical computing.
The approach is based on the preliminary preparation of an atomic medium: light first sets the atoms into a specific state, after which this medium is capable of altering the shape and polarization of complex laser beams. A key element of the model is optical vortices—laser beams with a spiral wavefront structure. In their "core," intensity drops to zero, and the size of the dark region is determined by the topological charge, which can take any integer value—both positive and negative.
The practical potential is impressive: up to 10,000 different states can be encoded in qudits—multilevel units of quantum information. This is a direct expansion of the capabilities of traditional qubits, which are limited to two states.
To control vector vortices, the researchers modeled the interaction of a beam with an atomic gas at three energy levels. The prepared medium inherits the spatial pattern of light: in some zones, atoms actively absorb radiation, while in others, they become nearly transparent. A feedback loop emerges—the atomic response reshapes the beam itself, forming a lobed structure with several bright regions around the center. Polarization is also transformed in the process.
Previously, such control required powerful magnetic fields and bulky equipment. The new theoretical model promises to simplify the architecture of quantum processors, enhance the security of quantum networks, and create ultra-precise optical sensors.
Expert opinion: This work demonstrates how fundamental physics can directly impact practical technologies. Eliminating magnetic fields not only reduces system costs but also lowers noise levels, which is critical for scaling quantum computing. However, transitioning from theory to a real prototype will require solving engineering challenges—stability of optical vortices and precision in preparing the atomic medium.