Figure 15

Figure 15: Light field in a coherent quantum state |α (ω )⟩. Left panel a) features a typical result one could get measuring the (normalized) electric field strength of the light wave in a coherent state as a function of time. Right panel b) represents a phase space picture of the results of measurement. The red dashed line in the left panel marks the mean value ⟹Eˆ(t)⟩. The red arrow in the right panel features the vector of the mean values of quadrature amplitudes, i.e., A, while the red dashed circle displays the error ellipse for the state |α(ω )⟩ that encircles the area of single standard deviation for a two-dimensional random vector ˆa of quadrature amplitudes. The principle radii of the error ellipse (equal in the coherent state case) are equal to square roots of the covariance matrix 𝕍 coh, i.e., to √ -- 1∕ 2.