Electron Spin Resonance spectroscopy with femtoliter detection volume
Abstract
We report electron spin resonance measurements of donors in silicon at millikelvin temperatures using a superconducting LC planar micro-resonator and a Josephson Parametric Amplifier. The resonator includes a nanowire inductor, defining a femtoliter detection volume. Due to strain in the substrate, the donor resonance lines are heavily broadened. Single-spin to photon coupling strengths up to 3~kHz are observed. The single shot sensitivity is 120 24~spins/Hahn echo, corresponding to ≈ 12 3~spins/Hz for repeated acquisition.
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