Scalable quantum logic spectroscopy

TL;DR

This paper introduces a scalable quantum logic spectroscopy technique using a Schrödinger cat interferometer, enhancing detection efficiency and stability for atomic clocks and fundamental physics tests with multiple ions.

Contribution

It develops a new method for scaling quantum logic spectroscopy to larger ion numbers using a Schrödinger cat interferometer, demonstrated with magnesium and aluminum ions.

Findings

Higher detection efficiency with more magnesium ions

Potential for improved optical clock stability

Enabling Heisenberg-limited quantum logic spectroscopy

Abstract

In quantum logic spectroscopy (QLS), one species of trapped ion is used as a sensor to detect the state of an otherwise inaccessible ion species. This extends precision measurements to a broader class of atomic and molecular systems for applications like atomic clocks and tests of fundamental physics. Here, we develop a new technique based on a Schr\"{o}dinger cat interferometer to address the problem of scaling QLS to larger ion numbers. We demonstrate the basic features of this method using various combinations of $^{25}\text{Mg}^+$ logic ions and $^{27}\text{Al}^+$ spectroscopy ions. We observe higher detection efficiency by increasing the number of $^{25}\text{Mg}^+$ ions. Applied to multiple $^{27}\text{Al}^+$, this method will improve the stability of high-accuracy optical clocks and could enable Heisenberg-limited QLS.