Characterizing two-dimensional superconductivity via nanoscale noise magnetometry with single-spin qubits

TL;DR

This paper introduces a nanoscale magnetometry technique using single-spin qubits to investigate two-dimensional superconductors, revealing insights into phase transitions, pairing symmetry, and collective modes through magnetic noise analysis.

Contribution

It presents a novel method for probing 2D superconductivity and pairing mechanisms via magnetic noise measurements with single-spin qubits, offering a non-invasive approach.

Findings

Magnetic noise from current fluctuations reveals superconducting transition and pairing symmetry.

Longitudinal current fluctuations probe collective modes like plasmons.

Spin fluctuation noise provides information on the spin structure of the pairing wave function.

Abstract

We propose nanoscale magnetometry via isolated single-spin qubits as a probe of superconductivity in two-dimensional materials. We characterize the magnetic field noise at the qubit location, arising from current and spin fluctuations in the sample and leading to measurable polarization decay of the qubit. We show that the noise due to transverse current fluctuations studied as a function of temperature and sample-probe distance can be used to extract useful information about the transition to a superconducting phase and the pairing symmetry of the superconductor. Surprisingly, at low temperatures, the dominant contribution to the magnetic noise arises from longitudinal current fluctuations and can be used to probe collective modes such as monolayer plasmons and bilayer Josephson plasmons. We also characterize the noise due to spin fluctuations, which allows probing the spin structure of the pairing wave function. Our results provide a non-invasive route to probe the rich physics of two-dimensional superconductors.