Rydberg atom quantum computers and simulators are limited by the lifetime of the Rydberg state, which affects coherence time and gate fidelities. Circular Rydberg states, with their maximal angular momentum providing excellent decay protection, are highly sought-after candidates to significantly increase the lifetime and overcome this limitation.
A group of researchers from the University of Stuttgart’s 5th Institute of Physics has made significant progress in quantum simulation and computing with Rydberg atoms by addressing the short lifetime issue. Circular Rydberg states show great potential in circumventing this obstacle.
In a groundbreaking achievement, the research team successfully generated and trapped circular Rydberg atoms of an alkaline-earth metal in an array of optical tweezers.
Dr. Florian Meinert, Head of the Junior Research Group at the 5th Institute of Physics leading the project, expressed excitement over the stability and extended lifetime of circular Rydberg atoms, stating, “This is exciting because they are particularly stable and can extend the lifetime of a quantum bit enormously. Therefore, they have great potential for developing more powerful quantum simulators.”
Strontium, chosen for its unique characteristics as an alkaline earth metal with two optically active electrons, was used to create the Rydberg atom.
The researchers were able to produce highly energetic circular states of a strontium isotope at room temperature, demonstrating an impressive lifespan of up to 2.55 milliseconds. By leveraging a cavity that absorbs blackbody background radiation, they could protect the sensitive Rydberg electron and maintain its stability.
Control and manipulation of a microwave quantum bit encoded in circular states played a crucial role in the research. Through coherent control, scientists successfully moved the qubit between states using microwave pulses without compromising its quantum information.
The versatile nature of circular Rydberg atoms makes them appealing for various applications. Their ability to be trapped and manipulated precisely in optical tweezers or other traps opens up possibilities for a scalable architecture that could benefit the construction of large quantum-bit systems based on neutral atoms.
Journal Reference:
- C. Hölzl et al., Long-Lived Circular Rydberg Qubits of Alkaline-Earth Atoms in Optical Tweezers, Physical Review X (2024). DOI: 10.1103/PhysRevX.14.021024
