An ion of the element ytterbium, used as a platform for quantum computing due to its suitable energy levels.Ytterbium ions are single atoms of the rare-earth element ytterbium that have been stripped of one or more electrons, turning them into electrically charged particles. In quantum computing, they serve as one of the most promising platforms for building qubits—the quantum equivalent of classical bits. Their appeal lies in their internal energy levels: ytterbium ions have a particularly stable 'clock' transition that can be used to encode quantum information, and they interact well with laser light, making them easy to manipulate and read out.
The use of ytterbium ions for quantum computing was pioneered in the early 2000s, with groups at NIST and the University of Oxford demonstrating key trapping and manipulation techniques. The element itself was discovered in 1878 by Jean-Charles Galissard de Marignac.
Ytterbium ions are typically trapped using electromagnetic fields in devices called Paul traps, which hold them in place in a vacuum. Laser beams are used to cool the ions to near absolute zero, slowing their motion so quantum states can be controlled. The qubit is encoded in two hyperfine energy levels of the ion's ground state, which are extremely stable against external disturbances. Quantum operations are performed by applying precisely tuned laser pulses that drive transitions between these levels, while the ions' mutual Coulomb repulsion allows them to become entangled, enabling multi-qubit computations.
Ytterbium ion qubits are used in experimental quantum computers, including those developed by companies like IonQ, and are also central to quantum network research, where they act as nodes for entanglement distribution.
Ytterbium ions are so stable that their optical clock transition is used as a candidate for redefining the SI second.










