Polarizing electron spins with a superconducting flux qubit

Electron spin resonance (ESR) is a useful tool to investigate properties of materials in magnetic fields where high polarization target electron spins required order obtain sensitivity. However, the smaller becomes, more difficult passively obtained by thermalization. Here, we propose employ superconducting flux qubit (FQ) polarize actively. We have overcome large energy difference between FQ and for efficient transfer among them. For this purpose, adopt spin-lock technique on Rabi frequency associated with spin-locking can match (Larmor) one spins. find that adding dephasing beneficial them, because otherwise are trapped dark states cannot be coupled FQ. show our scheme achieve realistic experimental conditions.