Extended Data Fig. 5: A phasor diagram showing how the tunable homodyne detector selects the measurement quadrature.
The sum of the local oscillator (LO) field (blue) and the signal field (red) selects the quadrature that is being measured (green). In the entire manuscript, we report this angle θs as the measurement quadrature. We determine the quadrature by knowing the power in all the three fields, and the visibility. The dashed green circle represents a contour of constant detection power. In order to keep the shot noise reference unchanged, we choose to always lock PDsqz with a constant total detected power, and vary the LO power to change the measurement quadrature. This has the effect of changing the angle θ of the LO.
