Synopsis

Trapping a Rydberg Ion

Physics 10, s62
A trapped ion excited to a hydrogen-like Rydberg state shows promise for qubit applications.
G. Higgins et al., Phys. Rev. X (2017)

Quantum physicists want the best of both worlds. Rather than choose between different qubit technologies, they’d prefer combining two of the top candidates—trapped ions and hydrogen-like Rydberg atoms—into one. As a step towards fulfilling this goal, Markus Hennrich from Stockholm University and his colleagues have excited a single strontium ion to a Rydberg state. The analysis of the system’s properties showed that exciting to one of the ion’s symmetric electronic states can mitigate unwanted electric field effects.

Trapped ions are currently among the head of the pack of possible qubit technologies, thanks to the isolated trap environment that allows long qubit lifetimes and low error rates. However, coupling qubits usually involves controlling the motion of all the ions, which poses a problem for large qubit ensembles. A Rydberg atom, by contrast, can have a long-range coupling interaction with its neighbors, owing to the large orbit of its single, highly excited outer electron. The challenge has been finding a way to effectively confine Rydberg atoms.

One possible solution is to excite trapped ions into Rydberg states. But the concern has been that the strong electric fields in an ion trap will shift or ionize the nearly unbound outer electron of the Rydberg state. Hennrich and colleagues explored the effect of an electric field on a single trapped strontium ion. To reach the desired Rydberg state, the team utilized two-photon excitation with counterpropagating laser beams, thus disturbing the ion less than in previous Rydberg ion experiments with single-photon excitation. The results showed that when the ion is excited into a spherically symmetric S orbital, the trap’s quadrupole field does not alter the ion’s electronic structure.

This research is published in Physical Review X.

–Michael Schirber

Michael Schirber is a Corresponding Editor for Physics based in Lyon, France.


Subject Areas

Quantum InformationAtomic and Molecular Physics

Related Articles

Connecting Qubits with a Topological Waveguide
Photonics

Connecting Qubits with a Topological Waveguide

A metamaterial waveguide with embedded qubits offers a new platform for probing and controlling topological phenomena. Read More »

Tracking a Single Ion in an Ultracold Gas
Atomic and Molecular Physics

Tracking a Single Ion in an Ultracold Gas

Direct observation of an ion moving through a Bose-Einstein condensate identifies the effect of ion-atom collisions on charge transport in an ultracold gas. Read More »

Quantum Drones Take Flight
Quantum Information

Quantum Drones Take Flight

A small prototype of a drone-based quantum network has successfully relayed a quantum signal over a kilometer of free space. Read More »

More Articles