Er:YSO Spin Hyperfine and Quadrupole Tensors using Josephson Bifurcation Amplifier

Using an ESR spectrometer based on Josephson Bifurcation Amplifier, we performed spectroscopy of Erbium-doped Y₂SiO₅ crystal at various magnetic field orientations and strengths. By fitting the resulting spectra, we extracted the ground state hyperfine and quadrupole tensor values for ¹⁶⁷Er:YSO. We discuss these tensor values, and compare them with values obtained using other methods, including conventional ESR spectroscopy, tunable resonators, and optical methods.