Figure 13

Noise reduction factor for a multi-mode twin-beam state as a function of the mean number of photons on one of the arms. Colored dots and error bars: experimental data obtained with the slow amplifier and DRS4 digitizer by selecting the peak values (black dots) or integrating over \(\tau = 2\mbox{ ns}\) before the peak (red dots); colored lines: theoretical expectations according to Eq. (5). The fitting parameters for the peak are: \(\eta = 0.182\), \(\mu = 9256\), \(\epsilon = 0.019\), \(\langle m_{\mathrm{dc}}\rangle =0.349\), \(t=0.913\) and \(\chi ^{(2)}=3.2\), while those for \(\tau = 2\mbox{ ns}\) are: \(\eta = 0.181\), \(\mu = 9990\), \(\epsilon = 0.020\), \(\langle m_{\mathrm{dc}}\rangle =0.348\), \(t=0.924\) and \(\chi ^{(2)}=6.2\)