  Visibility of singlet-triplet qubit readout is reduced to almost zero in
large magnetic field gradients due to relaxation processes. Here we present a
new readout technique that is robust against relaxation and allows for
measurement when previously studied methods fail. This technique maps the qubit
onto spin states that are immune to relaxation using a spin dependent electron
tunneling process between the qubit and the lead. We probe this readout's
performance as a function of magnetic field gradient and applied magnetic
field, and optimize the pulse applied to the qubit through experiment and
simulation.
