Fig. 2: Correlations induced between two photonic states after interacting with free electrons.

a Interaction scheme. After each interaction of an electron and the two photonic states, we trace out the electron. In certain cases, we then input another electron into the system and repeat. b The quantum mutual information as a function of the number of interactions increases with the number of interactions, indicating that correlations are induced. c Statistic of two coherent states with α₁ = 2 and α₂ = 3 after m = 0, 50, 100 consecutive interactions with free electrons. d P(n₁,n₂) − P(n₁) ⋅ P(n₂) after m = 0, 50, 100 consecutive interactions with free electrons increases and indicates correlations. The coupling strength in figures (b–d) is g_Q = 0.1.