Improvement of vacuum squeezing resonant on the rubidium D1 line at 795 nm

TL;DR

This paper demonstrates efficient generation of UV light and vacuum squeezed states at 795 nm using PPKTP crystals, achieving significant squeezing levels and analyzing loss mechanisms, with implications for quantum technologies.

Contribution

The study presents a high-efficiency UV generation and vacuum squeezing at 795 nm using PPKTP crystals, highlighting the impact of UV-induced losses on squeezing performance.

Findings

111 mW UV light at 397.5 nm from 191 mW fundamental light

Maximum squeezing of -5.6 dB achieved

UV-induced losses limit squeezing improvement

Abstract

We report on efficient generation of second harmonic laser and single-mode vacuum squeezed light of 795 nm with periodically poled KTiOPO4 (PPKTP) crystals. We achieved 111 mW of ultra-violet (UV) light at 397.5 nm from 191 mW of fundamental light with a PPKTP crystal in a doubling cavity, corresponding to a conversion efficiency of 58.1%. Using the UV light to pump an optical parametric oscillator with a PPKTP crystal, we realized -5.6 dB of a maximum squeezing. We analyzed the pump power dependence of the squeezing level and concluded that the UV light induced losses limit the improvement of the squeezing level. The generated squeezed light has huge potential application in quantum memory and ultra-precise measurement.