Observation of superconductivity and surface noise using a single trapped ion as a field probe

TL;DR

This paper demonstrates using a single trapped ion as a highly sensitive in situ sensor to detect electric field noise and observe superconducting transitions, revealing new insights into surface noise behaviors.

Contribution

It introduces a novel method to measure electric field noise with trapped ions and detects superconducting transitions non-invasively, advancing surface science and quantum sensing.

Findings

Achieved the lowest electric field noise level with a trapped ion.

First observation of a superconducting transition using an ion sensor.

Identified a crossover regime in surface noise frequency spectrum.

Abstract

Measuring and understanding electric field noise from bulk material and surfaces is important for many areas of physics. In this work, we introduce a method to detect in situ different sources of electric field noise using a single trapped ion as a sensor. We demonstrate the probing of electric field noise as small as $S_E = 5.2(11)\times 10^{-16}\,\text{V}^2\text{m}^{-2}\text{Hz}^{-1}$, the lowest noise level observed with a trapped ion to our knowledge. Our setup incorporates a controllable noise source utilizing a high-temperature superconductor. This element allows us, first, to benchmark and validate the sensitivity of our probe. Second, to probe non-invasively bulk properties of the superconductor, observing for the first time a superconducting transition with an ion. For temperatures below the transition, we use our setup to assess different surface noise processes. The measured noise shows a crossover regime in the frequency domain, which cannot be explained by existing surface noise models. Our results open perspectives for new models in surface science and pave the way to test them experimentally.