Single-spin qubit magnetic spectroscopy of two-dimensional superconductivity

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