Researchers at Chalmers University of Technology in Sweden have unveiled a new theoretical framework for quantum systems that could overcome the industry's most significant hurdle: decoherence. By introducing a concept they call "giant superatoms," the team aims to protect and control quantum information more effectively than current designs allow.
Quantum computers promise to revolutionize sectors like encryption and drug discovery by solving problems impossible for today’s silicon-based machines. However, these systems remain notoriously fragile. Known as qubits, the building blocks of quantum computers lose their data when exposed to even minor electromagnetic noise from their environment.
"Quantum systems are extraordinarily powerful but also extremely fragile," said Lei Du, a postdoctoral researcher in applied quantum technology at Chalmers. "The key to making them useful is learning how to control their interaction with the surrounding environment."
Combining giant atoms and superatoms
The new design merges two established concepts in physics: giant atoms and superatoms. A giant atom functions as a qubit that connects to light or sound waves at multiple, physically separated points. This allows the system to interact with its surroundings in several locations simultaneously.
"Waves that leave one connection point can travel through the environment and return to affect the atom at another point—similar to hearing an echo of your own voice before you've finished speaking," said Anton Frisk Kockum, an associate professor of applied quantum physics at Chalmers. "This self-interaction leads to highly beneficial quantum effects, reduces decoherence and gives the system a form of memory of past interactions."
While giant atoms improved the field’s understanding of quantum behavior, they previously struggled with entanglement—the process of linking multiple qubits to act as a single, coordinated unit. The researchers addressed this by integrating the concept of superatoms, which consist of several natural atoms sharing a single quantum state.
By layering these two concepts, the team created a system that functions as a single, engineered entity. This structure allows researchers to store and control quantum information from multiple qubits within one unit, bypassing the need for increasingly complex external circuitry.
"A giant superatom may be envisaged as multiple giant atoms working together as a single entity, exhibiting a non-local interaction between light and matter," Du explained.
Janine Splettstoesser, a professor of applied quantum physics and co-author of the study, noted that this advancement provides a new toolbox for the field. "They allow us to control quantum information and create entanglement in ways that were previously extremely difficult, or even impossible," she said.
The team is now moving from theoretical modeling to the construction phase. They intend to integrate these superatoms with existing quantum technologies to build more reliable and scalable computing platforms.
