  State readout of trapped-ion qubits with trap-integrated detectors can
address important challenges for scalable quantum computing, but the strong rf
electric fields used for trapping can impact detector performance. Here, we
report on NbTiN superconducting nanowire single-photon detectors (SNSPDs)
employing grounded aluminum mirrors as electrical shielding that are integrated
into linear surface-electrode rf ion traps. The shielded SNSPDs can be
successfully operated at applied rf trapping potentials of up to
$\mathrm{54\,V_{peak}}$ at $\mathrm{70\,MHz}$ and temperatures of up to
$\mathrm{6\,K}$, with a maximum system detection efficiency of
$\mathrm{68\,\%}$. This performance should be sufficient to enable parallel
high-fidelity state readout of a wide range of trapped ion species in typical
cryogenic apparatus.
