Figure 2: Characterization of the DLCZ quantum memory.
From: A waveguide frequency converter connecting rubidium-based quantum memories to the telecom C-band
(a) Temporal shape of anti-Stokes photons. The number of anti-Stokes detection events per time bin (bin size 1.28 ns) conditioned on a Stokes detection over 5 × 106 trials is plotted as a function of the arrival time (total integration time 109 s). The data shown correspond to ps=0.15%. The dashed line is a Gaussian fit with FWHM=11.4(9) ns. For these data, we have 
and ηR=35(1)%. (b) Second order cross-correlation function 
(red plain squares, left axis) and retrieval efficiency ηR (blue empty circles, right axis) as a function of the Stokes detection probability ps. For ps between 0.002 and 0.2% (shaded area), ηR is constant (32(2)%). The 
function increases until 56(8), before dropping for lower values of ps due to detector dark counts. The dashed line is the 
classical limit for two-mode squeezed states. For this plot, the number of trials varies from 4 × 106 to 6 × 107. The error bars represent ±1 s.d. assuming Poissonian statistics for the photon counts.
