Programming atoms with light: a new method for controlling quantum states without magnetic fields
A promising theoretical model has been developed at the Faculty of Physics of Vilnius University, which allows "programming" atoms using light, completely eliminating external magnetic fields. This breakthrough could radically simplify the creation of quantum computing systems and communication networks.
The essence of the approach is that light beams first set atoms to specific states, and then this pre-prepared medium changes the shape and polarization of complex laser pulses. The key element of the model is optical vortices—beams with a spiral wavefront structure, where the intensity drops to zero at the center. The size of this dark region is determined by the topological charge, which can take any positive and negative integer values without restrictions.
The practical potential is impressive: the system can generate up to 10,000 different states. This allows encoding information in qudits—multidimensional units of quantum information that significantly surpass traditional qubits with their two states in capacity. To control vector vortices, the researchers analyzed the interaction of the beam with an atomic gas, where atoms have three energy levels. In such a model, the prepared medium "remembers" the spatial pattern of light: in some areas, atoms actively absorb radiation, while in others they become almost transparent. Then feedback is triggered—the atomic response reshapes the beam itself.
As a result, instead of a simple ring structure, a petal-like pattern with several bright regions around the center is formed, and the polarization structure changes. Previously, such control required powerful external magnetic fields and complex equipment, making systems bulky and expensive.
Theoretically, this development opens the way to faster quantum processors, highly secure quantum networks, and ultra-precise optical sensors. My professional opinion: Eliminating magnetic fields is not just a simplification but a paradigm shift in controlling quantum systems. If the model is successfully implemented in practice, we could see compact and energy-efficient quantum devices in the coming years, which is especially critical for the development of the quantum internet and satellite communications.