Noise from a qubit tracks superconductor behavior in a field

The work demonstrates that the temperature dependence of magnetic noise near Tc deviates from expected behavior based on quasiparticle excitations, a result of enhanced critical superconducting fluctuations caused by even a weak applied magnetic field. By analyzing this magnetic noise, the team was able to distinguish between different vortex phases and extract key physical quantities like vortex oscillation frequencies and diffusivity. This approach complements recent advances in noise magnetometry and reveals a wealth of superconducting dynamical phenomena in an applied field. A single spin qubit’s depolarization rate provides a non-invasive method for characterizing dynamic fluctuations within superconductors, a technique previously challenging to achieve with high spatio-temporal resolution, particularly in two-dimensional materials. This approach uses isolated spin qubits, such as nitrogen vacancy centers in diamond or boron vacancy centers in…