In quantum computing, a notable contradiction remains: these machines offer unprecedented computing power, but they are at the same time extremely vulnerable. The slightest interaction with the outside world can erase the data they are processing, a major obstacle called decoherence. To create quantum computers that are both reliable and usable, scientists are exploring methods to preserve these delicate quantum states.
It is with this goal in mind that a team from Chalmers University of Technology, in Sweden, is presenting a new theoretical proposal named the "giant superatom". This architecture merges two quantum ideas to produce a more stable entity. The objective is to allow multiple qubits, the basic units of quantum information, to operate collectively while being better protected from external disturbances. This path could lead to a simplified design for future quantum systems.
Quantum entanglement can be represented as a quantum "link" between two entities.
Credit: TU Darmstadt The giant superatom is first inspired by the concept of a giant atom, an artificial qubit that interacts with its environment through several distinct connection points. This particularity allows for self-interaction effects, where a wave emitted at one point can come back to influence the atom at another location. According to one of the researchers involved, this gives the device a form of memory and significantly reduces decoherence. However, this architecture alone presented limitations.
To go further, the scientists integrated into it the principle of the superatom, where several natural atoms share a common quantum state and behave as a single entity. Their combination thus gives birth to the giant superatom, capable not only of better resisting disturbances, but also of producing entanglement between several qubits. This entanglement is indispensable for qubits to function as a unified whole, an essential condition for performing advanced quantum operations.
Theoretical model of giant superatoms, where two atoms share a quantum state and interact with waves at multiple points.
Credit: Lei Du, Chalmers University of Technology
This theoretical progress paves the way for potentially more accessible quantum technologies. The authors indicate that it could enable the storage and manipulation of information from several qubits within a single unit, which would reduce the need for extremely elaborate control electronics. This thus constitutes a notable step forward towards hybrid quantum systems, where different technological platforms could cooperate more easily.
The work of the Swedish team, detailed in
Physical Review Letters, shows that this design could reduce the need for expensive hardware. They are now working to transform this theoretical model into a real physical device. The goal is to participate in the development of scalable and robust quantum computers, as well as applications like quantum communication networks or ultra-sensitive detectors.