  The core issue for the implementation of the diamond NV centre qubits
technology is the sensitive readout of NV spin state. We have recently
demonstrated the photoelectric detection of NV magnetic resonances (PDMR),
anticipated to be faster and more sensitive than optical detection (ODMR). Here
we report on a PDMR contrast of 9 % - three times enhanced compared to previous
work - on shallow N-implanted diamond. Based on ab-initio modelling, we
demonstrate a novel one-photon ionization dual-beam PDMR protocol. We predict
that this scheme is significantly less vulnerable to the influence of defects
such as substitutional nitrogen.
