Just as for the simulations of the entangling gate, the fidelity of the filter pulses is highly dependent on the spectral linewidth and drops to around 0.6 as the linewidth exceeds the pulse bandwidth (Figure ). This decrease is approximately the same for both in-and antiphase coherences and for all operator pairs. As the difference between the resonance frequency of a spin packet and the frequency of the microwave pulse increases, the spin is less affected by the pulse and retains more of its original magnetisation. As such the application of filter pulses to broad spectra results in a statistical mixture of excited and unexcited magnetisation.