Chip Integrated Detectors for Trapped Ions

Integrated technologies greatly enhance the prospects for practical quantum devices based on trapped ions. Photonic integration of the laser light necessary for manipulating trapped ions constitutes an important step, and recent progress in this direction has garnered much enthusiasm. High-fidelity and rapid state detection is also important, not only at the conclusion of computations, but also along the way. Quantum sensors or computers which intend to leverage error correction schemes will need to perform targeted measurements and implement actions based on their results. In light of this, integrated detectors can offer advantages for system portability and can also greatly facilitate parallelism if a separate detector can be incorporated at each ion-trapping location. Here we demonstrate ion detection utilizing avalanche photodiodes (APDs) integrated directly into the substrate of silicon ion trapping chips. While less sensitive than superconducting nanowires, which have also been successfully demonstrated with trapped ions, APDs offer the significant advantage of room temperature operability. Using ^{88}Sr^+ ions and detecting their fluorescence along the 5^2P_{1/2} to 5^2S_{1/2} transition with integrated APDs, we report key figures of merit pertaining to their performance.