Fig. 2: Measuring cavity squeezing.
From: Observing the dynamics of quantum states generated inside nonlinear optical cavities
a Schematic of the experimental setup. b Phase-sensitive amplification in nonlinear drive-dissipative systems. When the DOPO is pumped below threshold (Ppump < Pth), the noise for a certain quadrature can be reduced below the standard quantum limit. c Measurement protocol for a cavity squeezed vacuum state. Pump and bias are controlled to both generate and measure the cavity squeezed vacuum state. d Bias–probability curves showing phase-sensitive amplification. e Reconstructed marginal Q function Qθ. Each curve is drawn by calculating the sensitivity from the bias–probability curve. f Reconstructed 2D Q function. Solid (dashed) black line represents the contour line at 1/e for squeezed vacuum state (analytical solution of quantum vacuum state). Black shaded area corresponds to the measurement uncertainty in the contour line at 1/e for the squeezed vacuum state.
