Quantum harmonic oscillator spectrum analyzers

TL;DR

This paper introduces a method to measure the noise spectrum of a quantum harmonic oscillator across a broad frequency range using a qubit, demonstrated with trapped ions, enabling better noise characterization in quantum systems.

Contribution

The work presents a novel technique for noise spectrum measurement in quantum harmonic oscillators using qubit sensing, covering previously inaccessible frequency ranges.

Findings

Successfully measured noise spectrum from 500 Hz to 600 kHz.

Demonstrated two implementations with high sensitivity.

Provided new insights into ion trap potential noise.

Abstract

Characterization and suppression of noise are essential for the control of harmonic oscillators in the quantum regime. We measure the noise spectrum of a quantum harmonic oscillator from low frequency to near the oscillator resonance by sensing its response to amplitude modulated periodic drives with a qubit. Using the motion of a trapped ion, we experimentally demonstrate two different implementations with combined sensitivity to noise from 500 Hz to 600 kHz. We apply our method to measure the intrinsic noise spectrum of an ion trap potential in a previously unaccessed frequency range.