Pulsed squeezed light via self-rotation

We report a pulsed squeezed vacuum in a warm ⁸⁷Rb vapor cell with one linearly polarized optical pulse near resonant on D1 transition. The experimental results show that the squeezing degree decreases from -3 ± 0.2 dB to 0 dB when the pulse width decreases from 400 ns to 50 ns with pulse period of 1μs. By theoretical analysis of the time evolution of the light-atom interaction, we determine that the effect of pulse width on the squeezing degree is mainly due to the evolution time that the population of each atomic level reaches a steady state. The pulsed quantum light is crucial for quantum information processing and precision measurements. Our results should be helpful to improve the performance of pulsed quantum light for quantum information, especially for precision measurements based on atomic systems, such as atomic magnetometers and atom interferometers.