Abstract
Trapped Rydberg ions are a promising new system for quantum information processing. They have the potential to join the precise quantum operations of trapped ions and the strong, long-range interactions between Rydberg atoms. Combining the two systems is not at all straightforward. Rydberg atoms are severely affected by electric fields which may cause Stark shifts and field ionization, while electric fields are used to trap ions. Thus, a thorough understanding of the physical properties of Rydberg ions due to the trapping electric fields is essential for future applications. Here, we report the observation of two fundamental trap effects. First, we investigate the interaction of the Rydberg electron with the trapping electric quadrupole fields which leads to Floquet sidebands in the excitation spectra. Second, we report on the modified trapping potential in the Rydberg state compared to the ground state that results from the strong polarizability of the Rydberg ion. By controlling both effects we observe resonance lines close to their natural linewidth demonstrating an unprecedented level of control of this novel quantum platform.
- Received 8 December 2016
DOI:https://doi.org/10.1103/PhysRevX.7.021038
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Synopsis
Trapping a Rydberg Ion
Published 7 June 2017
A trapped ion excited to a hydrogen-like Rydberg state shows promise for qubit applications.
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Popular Summary
There are many ways to store and manipulate information in a quantum computer. One leading approach uses ions trapped in an electromagnetic field; another relies on Rydberg atoms, which are atoms with one or more electrons that are highly energized. Both methods have their advantages. The quantum states of trapped ions can be precisely controlled, whereas Rydberg atoms offer tunable long-range interactions for processing quantum logic gates. Trapped Rydberg ions are a new contender. The method combines the advantages of both systems to offer a viable route toward creating a scalable quantum computer. But combining these systems is not easy. Rydberg atoms are highly sensitive to the strong electric fields used to trap ions; thus, it seems far-fetched to excite a trapped ion to a Rydberg state. We show that Rydberg ions can be well controlled in an ion trap.
We confined a single strontium ion in a type of electromagnetic “cage” known as a Paul trap and excited the ion to a Rydberg state with a laser. This allowed us to study how the ion interacts with the trap and how the potential of the trap itself is modified by the Rydberg state. Both effects suggest techniques that could be used for implementing quantum operations and logic gates. Ions in Rydberg states, for example, are unaffected by the trap, while states display a significant coupling between electronic and vibrational states.
This experiment demonstrates an unparalleled level of control over trapped Rydberg ions and reveals fundamental physical properties of this novel quantum platform. In particular, it shows that the system can, in principle, be controlled to the precision required for future applications.