(color online) (a), (b) I–Q clouds for the qubit states measured with the JPA pump off and on. The color point represents the single short read out state |0〉 (blue) or |1〉 (red). The clouds represent the signal scatter by the noise. The bigger black points represent the average centers of the cloud points. The position of the bigger black point represents the position of the state without noise. The dash line connected the center represents the projection axes. The distance of the center represents the relative separation of readout states |0〉 and |1〉. (c), (d) The histograms of the readout points with JPA pump off and on, the outlines are Gaussian fits to the histograms and used to estimate the separation fidelity and measurement fidelity. We also estimate the JPA noise temperature by comparing the readout results with JPA off and on.