Qubit state detection is an important part of a quantum computation. As number qubits in register increases, it necessary to maintain high fidelity accurately measure the multi-qubit state. Here we present experimental demonstration high-fidelity trapped ion with average single qubit error 4.2(1.5) ppm and 4-qubit 17(2) ppm, limited by decay lifetime qubit, using novel single-photon-sensitive c...