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

A Faster Atomic Compass
Atomic and Molecular Physics

A Faster Atomic Compass

An update to the polarization of the laser light used in an atom-based compass allows the technology to reveal the 3D alignment of a magnetic field in one snapshot rather than many. Read More »

Longer Trapping Expected for Graphene Atom Chips
Graphene

Longer Trapping Expected for Graphene Atom Chips

Predictions indicate that atom chips that use graphene contacts in their circuitry rather than metal ones can trap atoms for significantly longer times. Read More »

A Humming Lattice of Cold Atoms
Quantum Physics

A Humming Lattice of Cold Atoms

Researchers have produced an optical lattice of atoms that can generate sound, a previously unachieved feat. Read More »

More Articles