# Wide-field SU(1,1) interferometer

## TL;DR

This paper reports the first realization of a wide-field SU(1,1) interferometer with spatially multimode operation, demonstrating flat phase interference and quadrature squeezing, advancing quantum metrology and related fields.

## Contribution

The paper introduces a novel wide-field SU(1,1) interferometer with spatial multimode capabilities and flat phase interference, enabling broader applications in quantum sensing.

## Key findings

- Achieved flat interference phase over a broad angle.
- Demonstrated -4.3±0.7 dB quadrature squeezing.
- Enabled spatially multimode operation within a broad angle.

## Abstract

An ${\rm SU(1,1)}$ interferometer uses a sequence of two optical parametric amplifiers for achieving sub-shot-noise sensitivity to a phase shift introduced in between. We present the first realization of a wide-field ${\rm SU(1,1)}$ interferometer, where the use of a focusing element enables spatially multimode operation within a broad angle. Over this angle, the interference phase is found to be flat. This property is important for the high sensitivity to the phase front disturbance. Further, $-4.3\pm0.7$ dB quadrature squeezing, an essential requirement to the high sensitivity, is experimentally demonstrated for plane-wave modes inside the interferometer. Such an interferometer is useful not only for quantum metrology, but also in remote sensing, enhanced sub-shot-noise imaging, and quantum information processing.