High fidelity single-shot singlet-triplet readout of precision placed donors in silicon

We perform direct single-shot readout of the singlet-triplet states in exchange coupled electrons confined to precision placed donor atoms in silicon. Our method takes advantage of the large energy splitting given by the Pauli-spin blockaded (2, 0) triplet states, from which we can achieve a single-shot readout fidelity of 98.4 +- 0. 2 %. We measure the triplet-minus relaxation time to be of the order 3 s at 2.5 T and observe its predicted decrease as a function of magnetic field, reaching 0.5 s at 1 T.