Quantum-enhanced magnetometry by phase estimation algorithms with a single artificial atom

TL;DR

This paper demonstrates that modified phase estimation algorithms implemented on a superconducting transmon circuit can surpass classical flux sensitivity limits, approaching the Heisenberg limit, and significantly enhance quantum metrology capabilities.

Contribution

The study introduces and experimentally implements modified Kitaev and semiclassical Fourier-transform phase estimation algorithms on superconducting qubits for quantum-enhanced magnetometry.

Findings

Flux sensitivity exceeds classical shot-noise limit.

Approaches Heisenberg limit in flux measurement.

Potential to outperform existing flux sensors by orders of magnitude.

Abstract

Phase estimation algorithms are key protocols in quantum information processing. Besides applications in quantum computing, they can also be employed in metrology as they allow for fast extraction of information stored in the quantum state of a system. Here, we implement two suitably modified phase estimation procedures, the Kitaev- and the semiclassical Fourier-transform algorithms, using an artificial atom realized with a superconducting transmon circuit. We demonstrate that both algorithms yield a flux sensitivity exceeding the classical shot-noise limit of the device, allowing one to approach the Heisenberg limit. Our experiment paves the way for the use of superconducting qubits as metrological devices which are potentially able to outperform the best existing flux sensors with a sensitivity enhanced by few orders of magnitude.