For our purposes the two-qubit gate time is defined by the interaction between the two spin centres, which we determined using the 3P-DEER experiment (Figure ). At X-band frequencies (≈9.5 GHz) the EPR spectra of nitroxide spins is significantly broader than the excitation bandwidth of achievable rectangular pulses. This broadening is dominated by the hyperfine interaction of the electron spin-1 14 N nucleus, causing three distinct resonances corresponding to the nuclear spin states (Figure ). We choose to maximise the offset between the two frequencies, while remaining on resonance with the nitroxide spectrum, to minimise distortions which can be caused by pulse overlap in the frequency domain. As such the lower frequency, 𝜈 ) , corresponds to pulsing transitions within the high field 𝑚 < %& = -1 manifold, and the higher frequency, 𝜈 * , to the low field 𝑚 < %& = +1 manifold.