Data for: Electron readout contrast enhancement in the parallel nuclear regime of an exchange-coupled donor spin qubit system

Recent experiments on donor spin qubits in silicon have leveraged the
exchange interaction between electrons bound to separate donor nuclei to
perform two-qubit operations. A consistently observed yet unexplained
phenomenon in such systems is the significant increase in electron readout
contrast, measured via Elzerman-style readout to a single-electron
transistor (SET) island, when the donor nuclei are initialized in a
parallel spin orientation compared to an anti-parallel orientation. In
this work, we present a detailed analysis of the exchange-coupled donor
system in the parallel nuclear regime and propose a physical mechanism for
this effect. We attribute the enhanced readout contrast to an additional
electron tunneling event to the SET during a single read period, when the
donor nuclei are aligned in a parallel spin configuration.