# Polarization-Based Truncated SU(1,1) Interferometer based on Four-wave Mixing in Rb vapor

## TL;DR

This paper introduces a polarization-based truncated SU(1,1) interferometer using four-wave mixing in Rb vapor, achieving quantum noise suppression and entanglement detection with improved noise balancing and wide frequency range operation.

## Contribution

It presents a novel interferometer design that simplifies measurements and enhances noise suppression, demonstrating entanglement and squeezing over a broad frequency spectrum.

## Key findings

- Up to 2 dB quantum noise suppression below shot-noise limit.
- Successful detection of entanglement between quantum fields.
- Effective noise balancing improves differential measurement sensitivity.

## Abstract

We propose and demonstrate a polarization-based truncated SU(1,1) interferometer that outputs the desired optical joint-quadrature of a two-mode squeezed vacuum field and allows its measurements using a single balanced homodyne detector. Using such setup we demonstrated up to $\approx$2 dB of quantum noise suppression below the shot-noise limit in intensity-difference and phase-sum joint quadratures, and confirmed entanglement between the two quantum fields. Our proposed technique results in a better balance between the two ports of the detector and, consequently, in better common noise suppression for differential measurements. As a result, we were able to observe flat joint-quadrature squeezing and entanglement at wide range of detection frequencies: from several MHz (limited by the photodiode gain bandwidth) down to a few hundred Hz (limited by electronic noises).