Generation and Direct Detection of Broadband Mesoscopic Polarization-Squeezed Vacuum

TL;DR

This paper reports the generation of broadband polarization-squeezed vacuum states using a traveling-wave optical parametric amplifier, achieving 3dB squeezing through direct detection without a local oscillator.

Contribution

It introduces a novel method for producing broadband polarization-squeezed vacuum states with direct detection, eliminating the need for a local oscillator.

Findings

Achieved 3dB squeezing in polarization states.

Generated broadband squeezed vacuum over a wide wavelength range.

Demonstrated phase-dependent suppression of fluctuations below shot noise.

Abstract

Using a traveling-wave OPA with two orthogonally oriented type-I BBO crystals pumped by picosecond pulses, we generate vertically and horizontally polarized squeezed vacuum states within a broad range of wavelengths and angles. Depending on the phase between these states, fluctuations in one or another Stokes parameters are suppressed below the shot-noise limit. Due to the large number of photon pairs produced, no local oscillator is required, and 3dB squeezing is observed by means of direct detection.