Fig. 3: Characterization of the transfer function of the detection system to obtain the vacuum fluctuation noise level.
From: Homodyne-based quantum random number generator at 2.9 Gbps secure against quantum side-information
a Experimental set-up for the characterization. VATT variable optical attenuator, PD photo diode, ADC analog-to-digital converter, FPGA field-programmable gate array, RAM random access memory. b Power spectrum from a typical measurement. The transfer function is determined by the amplitude of the beat note. c Transfer function of the homodyne detector and the electronics including the analog-to-digital converter. Inset: transfer function with linear frequency scale.
