Performance Characterization of a Scalable Trapped Ion Based Quantum Computer

The rapid progress towards a scalable platform for atomic ion based quantum computing has resulted in a need for a careful characterization of the initial performance of basic qubit functions. This work characterizes the error rate for state readout, measurement crosstalk, and single qubit gates for a $^{171}$Yb$^+$ qubit in a surface trap. Photons scattered from the qubit are coupled into a multimode fiber using a high numerical aperture lens (0.6 NA) and directed towards a superconducting nanowire single photon detector (SNSPD). State dependent fluorescence is used to determine the state of the qubit, with an average state detection time of 12.3 $\mu$s and $6.9(5) \times 10^{-4}$ detection error. To characterize measurement crosstalk between two qubits, a measurement is performed on one qubit using a focused detection beam, and the coherence of a second qubit is measured as a function of the distance between the two. Gate set tomography is used for the characterization of global single qubit gates driven by a microwave field ($5.(6) \times 10^{-4}$ R$_x$($\frac{\pi}{2}$) error). Individual single qubit gates and two qubit gates driven by Raman transitions will be performed and characterized with tightly focused beams steered across the qubits by tilting MEMS mirrors.