Fig. 1. (Color online) Schematic of the system containing two external oscillators coupling through a nonlinear device, inset figure: nonlinear device internal circuit.

Fig. 1. (Color online) A simplified version of the circuit to estimate the transfer function.

Fig. 2. Step response of the circuit.

Fig. 2. (Color online) Complete system model; LC₁ coupling to LC₂ through InP HEMT transistor operating at 5 K.

Fig. 3. (Color online) (a) Quadrature variance versusg_m. (b) Second-order correlation function versusg_m.C_f = 0.02 pF,g_m3 = 1200 mA/V³,g_m2 = 200 mA/V²,V_RF = 1μV,κ =κ₁=κ₂= 0.001ω.

Fig. 4. (Color online) (a) Quadrature variance versusg_m, (b) second-order correlation function versusg_m for different g_m3(mA/V³);C_f = 0.02 pF,g_m2 = 200 mA/V²,V_RF = 1μV,κ = 0.001ω.

Fig. 5. (Color online) Second-order correlation function versusg_m. (a)g_m2 effect. (b) Feedback capacitance effect (C_f). (c) LC resonator decay rate effect (κ). (d) Input RF source amplitude effect (V_RF).g_m3 = 1200 mA/V³.