2017/11/30 by C. C. Bultink, B. Tarasinski, N. Haandbaek +5 · 1 citation
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1063/1.5015954
published as Appl. Phys. Lett. 112, 092601 (2018) · 10 pages, 6 figures
arxiv created 2018/04/05 · arxiv updated 2018/07/17
We present and demonstrate a general three-step method for extracting the quantum efficiency of dispersive qubit readout in circuit QED. We use active depletion of post-measurement photons and optimal integration weight functions on two quadratures to maximize the signal-to-noise ratio of the non-steady-state homodyne measurement. We derive analytically and demonstrate experimentally that the method robustly extracts the quantum efficiency for arbitrary readout conditions in the linear regime. We use the proven method to optimally bias a Josephson traveling-wave parametric amplifier and to quantify different noise contributions in the readout amplification chain.