Fig. 4: Characterization of noiseless amplification of coherent states by n-photon addition.
From: Experimental preparation of multiphoton-added coherent states of light
a, b The theoretical amplification gains g1(α) and g2(α) are plotted as lines and dots mark the experimental data. c, d Experimentally determined variances of amplitude quadratures Vx (purple squares) and phase quadratures Vp (blue triangles) of the amplified states are plotted together with the theoretical dependencies (purple dot-dashed lines and blue dashed lines). As a benchmark, the red solid lines in (c, d) indicate quadrature variance achievable by deterministic amplifier with the theoretical gains g1(α) and g2(α), respectively. The red dots show variances for deterministic amplification with the experimentally observed gains. Vacuum variance is set to 1 and indicated by the black dashed line. The error bars represent one standard deviation. For most of the data, the error bars are smaller than the symbol size. Data are plotted for n = 1 (a, c) and n = 2 (b, d).
