Fig. 2: Cyclic squeezing evolution with a detuned drive on the Kerr nonlinear oscillator for generating squeezed vacuum states.

a Experimental sequence for cyclic squeezing evolution and characterization with Wigner tomography. b Experimentally measured (top row) and numerically simulated (bottom row) Wigner function snapshots for the cyclic squeezing evolution of a vacuum state \(| N=0\left.\right\rangle\) in the first cycle (C = 1), showcasing that the quantum state no longer collapses during the evolution and evolves into a squeezed state at the final moment of each cycle. c Experimentally measured Wigner functions of the generated squeezed vacuum states at the final moment of the first 6 evolutionary cycles, obviously indicating that the squeezing is enhanced as the number of cycles increases.