Figure 3: Effectiveness of encryption.
From: Continuous-variable quantum computing on encrypted data
(a) Experimental setup using electro-optical amplitude and phase modulators (AM and PM, respectively) driven by Gaussian white noise sources to generate ensembles of encrypted coherent states. Both the input noise and the homodyne output were demodulated at 10.5 MHz and recorded by a data acquisition system (DAQ). PD: photo detectors. (b) The mutual information I(serverenc : clientin) for a coherent state chosen according to a Gaussian alphabet with variance Vin=0.6 SNU, which is then encrypted with a varied encryption variance Venc. For a fixed distribution of input states, the plot shows how an increased encryption noise decreases the server’s knowledge of the inputs. Error bars are smaller than the point size.
