Trap-integrated superconducting nanowire single-photon detectors for trapped-ion qubit state readout

State readout of trapped-ion qubits is usually achieved by observing qubit-state-dependent fluorescence from the ion while driving an optical cycling transition with laser light. The integration of photon detectors for fluorescence detection into the ion trap itself may benefit the development of many-qubit setups for applications like quantum computing. Superconducting nanowire single-photon detectors (SNSPDs) are promising candidates for trap-integrated detectors for high-fidelity trapped-ion qubit state readout. However, the strong oscillating electromagnetic fields that are typically used to trap and manipulate ions can affect the function of the SNSPDs significantly. In this work, we demonstrate an improved design to integrate SNSPDs into linear rf ion traps that reduces the susceptibility of the SNSPDs to applied rf trapping potentials. Our measurement results represent an improvement in rf tolerance by an order of magnitude with an increase in operation temperature from 3.5K to 6K compared to previous work.