  A single-spin qubit placed near the surface of a conductor acquires an
additional contribution to its $1/T_1$ relaxation rate due to magnetic noise
created by electric current fluctuations in the material. We analyze this
technique as a wireless probe of superconductivity in atomically thin two
dimensional materials. At temperatures $T \lesssim T_c$, the dominant
contribution to the qubit relaxation rate is due to transverse electric current
fluctuations arising from quasiparticle excitations. We demonstrate that this
method enables detection of metal-to-superconductor transitions, as well as
investigation of the symmetry of the superconducting gap function, through the
noise scaling with temperature. We show that scaling of the noise with
sample-probe distance provides a window into the non-local quasi-static
conductivity of superconductors, both clean and disordered. At low temperatures
the quasiparticle fluctuations get suppressed, yet the noise can be substantial
due to resonant contributions from collective longitudinal modes, such as
plasmons in monolayers and Josephson plasmons in bilayers. Potential
experimental implications are discussed.
